http://www.researchonline.mq.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24122 Determining the underlying mechanisms responsible for species-specific responses to climate change is important from a species management perspective. The grey-headed flying-fox, Pteropus poliocephalus, is listed as vulnerable but it also a significant pest species for orchardists and thereby presents an interesting management conundrum. Over the last century, the abundance of the grey-headed flying-fox, P. poliocephalus, in Australia has decreased due to a variety of threatening processes but has increased in abundance in urban areas. These flying-foxes are highly susceptible to extreme heat events which are predicted to increase in the future under climate change scenarios. Exceptionally hot days result in many deaths, the majority of whom are females with dependent young. This study examined the behavioural responses of roosting P. poliocephalus to temperature during the summer in their daytime roosts. Bats spent about 30% of their time resting at low temperatures, however, as temperature increased, fanning displaced resting as the predominant behaviour as bats attempted to cool themselves. Females with nursing young fanned significantly more often (P=0.001) and at a higher rate with rising temperature (P<0.001) than males and females without young (average proportion of time fanning 27%, 19% and 16%, and 4.6, 2.8 and 2.5 for gradient respectively). As a consequence, nursing females also rested less with rising temperature than the other demographic groups (P<0.001). These behavioural indicators suggest that nursing mothers are more vulnerable to heat stress than any other demographic category studied. The data highlight a clear need to monitor the most vulnerable demographic units as part of any species management program. Corrigendum to this article published in Appl. Anim. Behav. Sci. 145 (May (3-4)) (2013) 138. DOI:10.1016/j.applanim.2013.04.007. The author would like to correct the last name of second author ‘Jasmina Munich’. The correct name is ‘Jasmina Muhic’. 2013-05-16T08:12:47.388Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25517 A reduced predation risk is considered to be a major adaptive advantage of sociality. While most studies are concerned with non-predatory prey species, group-living predators are likely to face similar threats from higher-order predators. We studied the relationship between group size and predation risk in the subsocial crab spider Diaea ergandros by testing predictions from theoretical models including attack abatement as well as the formation of protective retreats. In a field survey, we found predatory clubionid spiders in 35 % of the D. ergandros nests and as predicted, nest size did not correlate with predator presence. In a subsequent laboratory experiment, we observed survival probability, nest construction activity and feeding behaviour including weight development between groups of different sizes as well as in the absence or presence of a predator. Large groups had an advantage in terms of survival and growth compared to smaller groups or single individuals. They also built significantly larger nests than smaller groups, supporting the idea of protective retreat formation being an adaptive benefit to group living. Even though clubionids did attack D. ergandros, they did not significantly affect overall mortality of D. ergandros. The feeding experiment showed that spiders fed on a larger proportion of flies in the presence of a predator. However, these groups gained significantly less weight compared to the control groups, indicating that the potential predators not only act as predators but also as food competitors, constituting a twofold cost for D. ergandros. 2013-05-15T14:22:38.902Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25521 Aim: Our objective was to reconstruct a species-level phylogeny of the genus Delias, to elucidate their finer-scale biogeography and to test boundaries between closely related taxa. Location: Indo-Australian region, with a focus on Wallacea. Methods: Sequence data from 131 taxa, representing all recognized species groups and more than half of the known species of Delias, were used in the analysis. Phylogenetic analyses based on molecular characters of the mitochondrial gene cytochrome c oxidase subunit I (COI) and nuclear genes wingless and elongation factor 1α (EF-1α) were carried out using maximum parsimony and Bayesian inference. Biogeographical reconstructions were undertaken using the parsimony-based method dispersal-vicariance analysis and the dispersal-extinction-cladogenesis model as implemented in rasp and Lagrange, respectively. Results: The phylogenetic hypothesis resolved 14 distinct clades, here designated the nysa, isse, pasithoe, belladonna, ladas, geraldina, aroae, eichhorni, sagessa, aganippe, hyparete, belisama, albertisi and nigrina species groups. Delias blanca Felder and Delias chrysomelaena Snellen van Vollenhoven were transferred to the pasithoe and isse species groups, respectively. We demonstrate that the barcode region of COI is useful for the delineation of closely related, more recently diverged, Delias species. Species diversification in Delias, for the most part, is shown to pre-date the Pleistocene, even in montane mainland New Guinea where numerous phenotypically similar sister species co-occur. Main conclusions: Sibling Delias species found in sympatry are largely restricted to those clades confined to mainland New Guinea, where most species occur in high-elevation habitats. Conversely, clades with large geographical ranges are composed of essentially allopatric taxa. Although an Australian Plate origin is plausible for the genus, Delias is likely to have colonized islands peripheral to Australia during the early stages of its evolution (i.e. during the Miocene), as evidenced by the presence of older lineages in Wallacea and also in islands of the south-western Pacific. 2013-05-15T14:22:27.130Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25544 We describe a microsatellite panel of 12 newly developed and four cross-amplification loci for the endangered Australian sea lion, Neophoca cinerea. Next-generation 454 sequencing was used to obtain species-specific partial genomic library. We genotyped 28 individuals sampled from a single breeding colony to characterize these 16 polymorphic loci. Number of alleles per locus ranged from three to seven, and observed and expected heterozygosites from 0.333 to 0.852 and from 0.377 to 0.787, respectively. These markers will be used to examine genetic diversity, genetic connectivity among colonies and the mating system of Australian sea lions. 2013-05-15T14:21:44.102Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25557 We quantified sexual size dimorphism, reproduction, and diet in the flap-necked chameleon, Chamaeleo dilepis, using museum specimens. Females were larger than males in both snout-vent length (SVL) and pelvic width. The smallest sexually reproductive female was 80 mm SVL, whereas the smallest mature male was 60 mm. Female body size also correlated with clutch size (mean: 44.2, range: 19–74) and volume, suggesting the female-biased size dimorphism may be the product of fecundity selection. Males and females have slightly asynchronous reproductive cycles but breed during spring–summer. Chamaeleo dilepis feeds on a range of arthropods, but their diet is dominated both numerically and volumetrically by orthopterans, followed by coleopterans. 2013-05-15T14:21:09.137Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:17534 We present a simple theoretical land-surface classification that can be used to determine the location and temporal behavior of preferential sources of terrestrial dust emissions. The classification also provides information about the likely nature of the sediments, their erodibility and the likelihood that they will generate emissions under given conditions. The scheme is based on the dual notions of geomorphic type and connectivity between geomorphic units. We demonstrate that the scheme can be used to map potential modern-day dust sources in the Chihuahuan Desert, the Lake Eyre Basin and the Taklamakan. Through comparison with observed dust emissions, we show that the scheme provides a reasonable prediction of areas of emission in the Chihuahuan Desert and in the Lake Eyre Basin. The classification is also applied to point source data from the Western Sahara to enable comparison of the relative importance of different land surfaces for dust emissions. We indicate how the scheme could be used to provide an improved characterization of preferential dust sources in global dust-cycle models. Copyright 2011 by the American Geophysical Union. 2013-05-09T10:36:51.929Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:21601 A simple process-based model for the consumption of atmospheric hydrogen (H₂) has been developed. The model includes a description of diffusion and biological processes which together control H₂ flux into the soil. The model was incorporated into the LPJ-WHyMe Dynamic Global Vegetation Model, and used to simulate H₂ fluxes over the 1988-2006 period. The model results have been confronted with field and laboratory measurements. The model reproduces observed seasonal cycles of H₂ uptake at different sites and shows a realistic sensitivity to changes in soil temperature and soil water content in comparisons with field and laboratory measurements. A recent study, based on 3D atmospheric model inversion, found an increase of the global H₂ sink from soils, with a trend of -0.77 Tg a⁻²for the 1992-2004 period (fluxes are negative as soils act as a sink for atmospheric H₂). For the same period, however, our process-based model calculates a trend of only -0.04 Tg a⁻². Even when forced with drastic changes in soil water content, soil temperature and snow cover depth, our model is unable to reproduce the trend found in the inversion-based study, questioning the realism of such a large trend. 2013-05-09T10:06:18.352Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23417 Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo- fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming. 2013-05-09T09:52:35.930Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25376 17 pages(s) 2013-05-09T09:36:57.921Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25400 Social learning is taxonomically widespread and can provide distinct behavioural advantages, such as in finding food or avoiding predators more efficiently. Although extensively studied in bony fishes, no such empirical evidence exists for cartilaginous fishes. Our aim in this study was to experimentally investigate the social learning capabilities of juvenile lemon sharks, Negaprion brevirostris. We designed a novel food task, where sharks were required to enter a start zone and subsequently make physical contact with a target in order to receive a food reward. Naive sharks were then able to interact with and observe (a) pre-trained sharks, that is, 'demonstrators', or (b) sharks with no previous experience, that is, 'sham demonstrators'. On completion, observer sharks were then isolated and tested individually in a similar task. During the exposure phase observers paired with 'demonstrator' sharks performed a greater number of task-related behaviours and made significantly more transitions from the start zone to the target, than observers paired with 'sham demonstrators'. When tested in isolation, observers previously paired with 'demonstrator' sharks completed a greater number of trials and made contact with the target significantly more often than observers previously paired with 'sham demonstrators'. Such experience also tended to result in faster overall task performance. These results indicate that juvenile lemon sharks, like numerous other animals, are capable of using socially derived information to learn about novel features in their environment. The results likely have important implications for behavioural processes, ecotourism and fisheries. 2013-05-09T09:36:05.745Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25433 Bipolar affective disorder is a heritable, relatively common, severe mood disorder with lifetime prevalence up to 4%. We report the results of a genome-wide linkage analysis conducted on a cohort of 35 Australian bipolar disorder families which identified evidence of significant linkage on chromosome 15q25-26 and suggestive evidence of linkage on chromosomes 4q, 6q and 13q. Subsequent fine-mapping of the chromosome 15q markers, using allele frequencies calculated from our cohort, gave significant results with a maximum two-point LOD score of 3.38 and multipoint LOD score of 4.58 for marker D15S130. Haplotype analysis based on pedigree-specific, identical-by-descent allele sharing, supported the location of a bipolar susceptibility gene within the Zmax-1 linkage confidence interval of 17 cM, or 6.2 Mb, between markers D15S979 and D15S816. Non-parametric and affecteds-only linkage analysis further verified the linkage signal in this region. A maximum NPL score of 3.38 (P= 0.0008) obtained at 107.16cM (near D15S130), and a maximum two-point LOD score of 2.97 obtained at marker D15S1004 (affecteds only), support the original genome-wide findings on chromosome 15q. These results are consistent with four independent positive linkage studies of mood and psychotic disorders, and raise the possibility that a common gene for susceptibility to bipolar disorder, and other psychiatric disorders may lie in this chromosome 15q25-26 region. 2013-05-09T09:35:07.476Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25434 Bipolar affective disorder is a major psychiatric illness with a population prevalence of up to 1.6%. The disorder is genetically complex. To date, no specific gene or DNA sequence variation that predisposes to the disorder has been described, however several susceptibility loci have been proposed through genetic linkage analysis. We previously identified onesuch susceptibility locus on chromosome 4q35, and refined the interval harboring this susceptibility gene to a size that is amenable to positional cloning. Several independent studies have now been described that support the presence of a susceptibility gene at this locus. In order to identify candidate genes for testing association with bipolar disorder, we previously established a comprehensive transcript map that encompasses the chromosome 4q35 susceptibility locus implicated in our linkage analysis. In this study, we have selected fulllength genes from the transcript map and determined the genomic structure of each gene. We identified informative, intragenic single nucleotide polymorphisms (SNPs) by screening all exons and flanking intron sequences in affected individuals from seven bipolar pedigrees that we previously reported as showing evidence for linkage to chromosome 4q35. Analysis of these SNPs was then extended to our unrelated bipolar case-control cohort to test for association with the disorder. Our data suggests that all genes analyzed can be excluded from direct involvement in the disorder. We have therefore, excluded approximately half the genes within the chromosome 4q35 candidate interval from playing a direct pathogenic role in bipolar disorder. 2013-05-09T09:35:04.174Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25494 The Lake Eacham rainbowfish (Melanotaenia eachamensis) was once thought to be confined to its type locality within the Lake Eacham World Heritage National Park. M. eachamensis disappeared from the lake following the translocation of several species into the lake and the species was pronounced extinct in the wild in 1987. In a 2007 survey we noticed that rainbowfish were present in the lake once again. We used a molecular marker to identify these fish and the likely source population. Analysis of the D-loop region of mitochondrial DNA revealed that the species now present in the lake is Melanotaenia splendida, and is most closely related to several M. splendida populations in the immediate vicinity. Here we explore a range of scenarios that may have led to this colonisation event and highlight the dangers associated with translocation. 2013-05-09T09:34:34.204Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25490 Over the expanse of the salt lakes of the Lake Eyre basin lives a species of ant of the genus Melophorus (as yet unnamed), both on the edges of the salt-pan and on the salt-pan itself. Most of the foragers are small (~3.0-5.0mm), but ~10% of the ants seen foraging are much larger (~7.0mm) and may form a soldier caste. Foragers are thermophilic and show diurnal activity, displaying a single-peaked activity profile across the day, with activity time limited to 2-6h at most each day (during the late-summer study period, 28 February to 28 March 2012). They forage largely for dead arthropods, but also occasionally bring home plant materials. Foraging success (not considering possible liquid food intake) is ~20%, resembling the success rate of their congener Melophorus bagoti, which inhabits cluttered environments. When displaced with food from a feeder, the ants head systematically and precisely in the feeder-to-nest direction, thus exhibiting path integration abilities involving celestial compass cues. The study of this species provides an interesting comparative perspective in contrasting desert ants of the same genus and thus genetic heritage inhabiting habitats differing in complexity of panoramic terrestrial cues as well as comparing ecologically similar species inhabiting the same type of habitat (in the present case, salt-pans) but differing in their phylogenetic relationships. 2013-05-09T09:30:39.071Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25482 Arthropods are a much-studied group of animals. They include insects, spiders, and hard-shelled invertebrates such as crabs. This chapter reviews four broad topics on the navigational behavior of arthropods. The first is path integration, the ability to keep track of the straight-line distance and direction from one’s starting point. The second is route behavior, in which landmarks figure in various ways. The third is the use of landmarks, both to chart an initial course and to pinpoint a target. The fourth is map-like navigational behavior. The chapter presents an overview including some classic work and current trends and issues. 2013-05-09T01:00:13.505Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25347 Bright colours often communicate important information between conspecifics. In sexually dichromatic species where males exhibit bright colours, two hypotheses are often invoked to explain the function of the colour. First, if a male's bright colour contains information about his quality, females may prefer brighter males. Equally, male colour may reliably provide other males with information about fighting ability or resource holding potential. In such circumstances, brighter males may win altercations and/or males may use rival colour to assess their likelihood of winning an interaction. In the chameleon grasshopper (Kosciuscola tristis), males but not females turn bright turquoise when their body temperature exceeds 25 °C. In this study, we tested whether the turquoise phase of colour change has a signaling role in inter- and intrasexual contexts. We predicted that females would prefer bright turquoise males over dull males, but found no evidence from several choice experiments to support this hypothesis. We also predicted that brighter males would win more fights than duller males. Whilst we did not find that brighter males won more fights in staged experiments, we found that the brightness of males who chose to enter fights was significantly correlated with their opponents' brightness. Our results suggest that the brightness of males' turquoise phase may provide competitors with important information about their rival's fighting ability. 2013-05-02T01:33:48.379Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25351 Body colours can result in different internal body temperatures, but evidence for the biological significance of colour-induced temperature differences is inconsistent. We investigated the relationship between body colour and temperature in a model insect species that rapidly changes colour. We used an empirical approach and constructed a heat budget model to quantify whether a colour change from black to turquoise has a role in thermoregulation for the chameleon grasshopper (Kosciuscola tristis). Our study shows that colour change in K. tristis provides relatively small temperature differences that vary greatly with wind speed (0.55 °C at ms⁻¹ to 0.05 °C at 10 ms⁻¹). The biological significance of this difference is unclear and we discuss the requirement for more studies that directly test hypotheses regarding the fitness effects of colour in manipulating body temperature. 2013-05-02T01:33:24.808Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25356 Gouldian Erythrura gouldiae and Long-tailed Finches Poephila acuticauda are morphologically and ecologically similar sympatric species, for which social dominance relationships are likely to determine access to critical limiting resources. Building on previous research showing that Long-tailed Finches dominate competition for nest-sites, I staged dyadic contests for food between the two species in captivity in order to test social dominance dynamics under controlled conditions. Long-tailed Finches were likely to dominate interactions with Gouldian Finches and expressed higher levels of aggression while competing for access to food. These results suggest a stable dominance relationship between the two species which could be affecting Gouldian Finches' access to food resources in the wild, potentially constraining their ability to recover from recent population declines. 2013-05-02T01:32:49.118Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25362 Many cooperative bird species have an extended period of post-fledging care. Despite the fact that this period of care can last up to several months, it remains a relatively understudied stage of chick development. This period, when young are actively begging but highly mobile, provides an opportunity for young to maximise the amount of care they receive by selectively choosing particular adults to beg from. In pied babblers Turdoides bicolor (a cooperatively breeding passerine), fledglings closely follow foraging adults and beg for food regularly (a behavioural interaction termed social foraging). Using a combination of natural observations and experimental manipulations, we found that fledgling pied babblers preferentially socially forage with adult care-givers who have high foraging success, since this results in young receiving more food. By supplementally feeding adults to artificially increase their foraging success, we increased the proportion of time that fledglings chose to socially forage with them, confirming that fledglings are selectively choosing dyadic interactions with the best adult foragers. These results indicate that pied babbler fledglings are sensitive to and can respond to short-term changes in adult foraging success, enabling them to maximize their nutritional intake, a behavioural adjustment that has long-term benefits in this system. 2013-05-02T01:31:23.149Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25371 Species of Eunicida (polychaetous annelids) have complex jaw apparatuses with ventral mandibles growing throughout life, but dorsal maxillae undergoing successive moulting episodes. Jaw ontogeny was studied in the eunicid Marphysa fauchaldi, from the appearance of the mandibles and larval maxillae through two moults during the transformation to juvenile and sub-adult maxillae. Although larval maxillae have been previously known, this is the first description of the juvenile stage for Eunicidae. The immature maxillary stages of M. fauchaldi were compared with those of Diopatra aciculata of the sister family Onuphidae, and, in a novel approach, extended deep into the fossil record by searching among adult stages of extinct eunicidans. Although neither the larval nor the juvenile stage resembles any complete fossil apparatus, each stage has features of separate maxillae known from different geological times. The larval maxilla II of both species is similar to the jaws of the Early Ordovician xanioprinids, the juvenile maxilla I of D. aciculata strikingly resembles those of the adult Palaeozoic Atraktoprion, whereas that of M. fauchaldi resembles those of Brochosogenys and allies. Thus, the extant taxa analysed represent cases in which ontogeny recapitulates phylogeny. It may also suggest that onuphid jaws are closer to the ancestral state than those of eunicids. This study opens a new perspective on evolutionary patterns, discusses asymmetry in jaw apparatuses relating to the basal plate concept, the apparent absence of early ontogenetic stages from the fossil record and cautions the use of architectural types in the interpretation of fossil maxillary apparatuses. 2013-05-02T01:30:12.252Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25322 Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct link between morphological changes detectable in the fossil record and biological species. Here we quantify the relative frequencies of cladogenesis and anagenesis for macroperforate planktic Foraminifera, which arguably have the most complete fossil record currently available, to address this question. Analyzing this record in light of molecular evidence, while taking into account the precision of fossil dating techniques, we estimate that the fraction of speciation events attributable to anagenesis is <19% during the Cenozoic era (last 65 Myr) and <10% during the Neogene period (last 23 Myr). Our central conclusion-that cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scales-differs markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence. 2013-04-26T05:20:42.980Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25324 The Asian honey bee Apis cerana and the European honey bee Apis mellifera are closely related and morphologically very similar. Where these species coexist, they appear to compete, but the outcomes of competition vary enormously between locations. Here, we report comparative behavioural data for A. cerana and A. mellifera in China gathered by tracking bees using radio frequency identification. Both species organise their division of labour by temporal polyethism and have remarkably similar demographic structure. Analyses of the homing capacities of both species following large-scale displacement suggest that A. mellifera colonies have a larger range than A. cerana. We observed that relocation of A. mellifera to a new environment disrupted colony function for 3 weeks. Our data show that A. mellifera and. A cerana occupy extremely similar behavioural niches, and therefore, the potential for competition between these species is very high. 2013-04-26T05:20:35.903Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25327 Coconut, oil, and date palms are important crops in the tropics and are attacked by dynastids that cause loss of production or death of hosts. Knowledge of their breeding sites has been extended since a previous review in 1980. The fungus Metarhizium anisopliae has potential as a biopesticide against immature stages in friable breeding sites. The molecular biology and ultrastructure of Oryctes rhinoceros Nudivirus (OrNV), disseminated by adults, have been studied, and this pathogen can reduce O. rhinoceros populations and damage when introduced into new locations, especially where damage had been high. New PCR techniques may enable reliable quantification of dosages ingested and hence virulence of different isolates. Male-produced aggregation pheromones have been identified in several species, for which they may have management potential, having been used commercially for trapping O. rhinoceros in oil palm plantations in Southeast Asia, and tested against O. monoceros in Africa. 2013-04-24T09:31:57.839Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25276 3 page(s) 2013-04-22T20:11:32.952Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25284 Over the last decade more and more published papers have presented supposedly interesting diversity curves. Almost all of this literature has used either (a) raw taxon counts or (b) sampling standardised counts produced by outdated methods such as rarefaction, as opposed to shareholder quorum subsampling (SQS). Few authors have asked whether they even have enough data to perform standardisation, a question easily answered by examining statistical coverage of frequency distributions (Good's u, the measure SQS seeks to hold constant). Data from the Paleobiology Database are sufficient to compute stage-level curves for many major inver tebrate groups and for Cenozoic mammals from North America and Europe, as well as epoch-level curves for insects. But sample sizes will most likely always be inadequate for (say) mammals from other continents and for sporadically preserved groups such as vascular plants, sponges, decapods, asterozoans, bony fishes, amphibians, marine reptiles, crocodylians, birds, and non-avian dinosaurs. Computing proper origination and extinction rates with low binomial error is even more challenging. Thus, only so much can be said about taxonomic diversity, and in most cases everything important already has been said. There has been a concurrent explosion of literature on the tangential question of whether and why raw, unstandardised diversity curves correlate with rock amount proxies. Raw taxon counts are intrinsically uninteresting, and if standardisation is unfeasible curves simply shouldn't be presented. Rock amount by itself is also of no intrinsic geological or biological interest. It may be time for us all to step back from publishing diversity curves. 2013-04-22T20:10:27.574Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:21572 Oxygen deprivation limits the energy available for cellular processes and yet no comprehensive ATP budget has been reported for any plant species under O(2) deprivation, including Oryza sativa. Using 3-d-old coleoptiles of a cultivar of O. sativa tolerant to flooding at germination, (i) rates of ATP regeneration in coleoptiles grown under normoxia (aerated solution), hypoxia (3% O(2)), and anoxia (N(2)) and (ii) rates of synthesis of proteins, lipids, nucleic acids, and cell walls, as well as K(+) transport, were determined. Based on published bioenergetics data, the cost of synthesizing each class of polymer and the proportion of available ATP allocated to each process were then compared. Protein synthesis consumed the largest proportion of ATP synthesized under all three oxygen regimes, with the proportion of ATP allocated to protein synthesis in anoxia (52%) more than double that in normoxic coleoptiles (19%). Energy allocation to cell wall synthesis was undiminished in hypoxia, consistent with preferential elongation typical of submerged coleoptiles. Lipid synthesis was also conserved strongly in O(2) deficits, suggesting that membrane integrity was maintained under anoxia, thus allowing K(+) to be retained within coleoptile cells. Rates of protein synthesis in coleoptiles from rice cultivars with contrasting tolerance to oxygen deficits (including mutants deficient in fermentative enzymes) confirmed that synthesis and turnover of proteins always accounted for most of the ATP consumed under anoxia. It is concluded that successful establishment of rice seedlings under water is largely due to the capacity of coleoptiles to allocate energy to vital processes, particularly protein synthesis. 2013-04-22T03:50:20.031Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25252 Leslie Russell Blake was a young Australian surveyor and geologist of great talent who made an outstanding contribution to our knowledge of Macquarie Island whilst a member of Douglas Mawson's Australasian Antarctic Expedition (AAE) during 1911-1914. He was a member of the five-man team that spent nearly two years on Macquarie Island establishing their base at the northern end of the island. Blake spent much of his time away from the base surveying and making geological observations. His topographical map of the island was the standard until modern techniques such as aerial photography, satellite imagery, airborne synthetic aperture radar and GPS technology enabled the island to be mapped in detail. During the First World War Blake served with the Australian Imperial Forces and was awarded a Military Cross for a survey of the front line before the attack at Pozieres. His death just days before the end of the First World War meant that he never finished writing up his scientific notes. It says much for the quality of his field reports that Douglas Mawson was eventually able to publish the work. Sadly, the fact that it was not published until 1943, and then only under Mawson's name, meant that Leslie Russell Blake has been largely forgotten. 2013-04-18T05:10:18.282Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25210 We examined the structure-function relationships that underlie the aerobic capacities of marsupial mammals that hop. Marsupials have relatively low basal metabolic rates (BMR) and historically were seen as 'low energy' mammals. However, the red kangaroo, Macropus rufus (family Macropodidae), has aerobic capacities equivalent to athletic placentals. It has an extreme aerobic scope (fAS) and its large locomotor muscles feature high mitochondrial and capillary volumes. M. rufus belongs to a modern group of kangaroos and its high fAS is not general for marsupials. However, other hopping marsupials may have elevated aerobic capacities. Bettongia penicillata, a rat-kangaroo (family Potoroidae), is a small (1 kg), active hopper whose fAS is somewhat elevated. We examined the oxygen delivery system in its muscles to ascertain links with hopping. An elevated fAS of 23 provided a relatively high maximal aerobic oxygen consumption (VO₂,max) in B. penicillata; associated with this is a skeletal muscle mass of 44% of body mass. Ten muscles were sampled to estimate the total mitochondrial and capillary volume of the locomotor muscles. Values in B. penicillata were similar to those in M. rufus and in athletic placentals. This small hopper had high muscle mitochondrial volume densities (7.1-11.9%) and both a large total capillary volume (6 ml kg⁻¹ body mass) and total capillary erythrocyte volume (3.2 ml kg⁻¹). Apparently, a considerable aerobic capacity is required to achieve the benefits of the extended stride in fast hopping. Of note, the ratio of VO₂,max to total muscle mitochondrial volume in B. penicillata was 4.9 ml O₂ min⁻¹ ml⁻¹. Similar values occur in M. rufus and also placental mammals generally, not only athletic species. If such relationships occur in other marsupials, a fundamental structure-function relationship for oxygen delivery to muscles likely originated with or before the earliest mammals. 2013-04-16T06:52:02.422Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25211 Seasonal patterns in territorial behaviour are common in many species, and are often attributed to the adaptive benefits of increased defence or the provision of information to potential competitors or mates during the breeding season. However, because defence behaviour is likely to be costly in terms of time and energy, an alternative possibility is that decreases in the nonbreeding season are a consequence of reduced food availability. We studied territoriality in the pied babbler, Turdoides bicolor, a cooperatively breeding bird species that defends permanent territories. Groups interacted with rivals less and responded less strongly to an experimentally simulated intrusion of neighbours in nonbreeding periods compared to the breeding season. Foraging efficiency and biomass intake were significantly lower in the nonbreeding season, which resulted in birds being significantly lighter at this time of year. Finally, a feeding experiment in the nonbreeding season showed that groups given supplementary food significantly increased their response to a simulated territorial intrusion. These results indicate that the reduction in territorial behaviour during the nonbreeding season may be attributed, at least in part, to a reduction in food availability. We suggest that future studies on seasonal variation in territorial behaviour, especially those investigating species in which two or more individuals combine their defence, should take this potential constraint into account. 2013-04-16T06:51:58.482Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25220 Bipolar affective disorder is one of the most common mental illnesses with a population prevalence of approximately 1%. The disorder is genetically complex, with an increasing number of loci being implicated through genetic linkage studies. However, the specific genetic variations and molecules involved in bipolar susceptibility and pathogenesis are yet to be identified. Genetic linkage analysis has identified a bipolar disorder susceptibility locus on chromosome 4q35, and the interval harbouring this susceptibility gene has been narrowed to a size that is amenable to positional cloning. We have used the resources of the Human Genome Project (HGP) and Celera Genomics to identify overlapping sequenced BAC clones and sequence contigs that represent the region implicated by linkage analysis. A combination of bioinformatic tools and laboratory techniques have been applied to annotate this DNA sequence data and establish a comprehensive transcript map that spans approximately 5.5 Mb. This map encompasses the chromosome 4q35 bipolar susceptibility locus, which localises to a 'most probable' candidate interval of approximately 2.3 Mb, within a more conservative candidate interval of approximately 5 Mb. Localised within this map are 11 characterised genes and eight novel genes of unknown function, which together provide a collection of candidate transcripts that may be investigated for association with bipolar disorder. Overall, this region was shown to be very gene-poor, with a high incidence of pseudogenes, and redundant and novel repetitive elements. Our analysis of the interval has demonstrated a significant difference in the extent to which the current HGP and Celera sequence data sets represent this region. 2013-04-16T06:51:15.662Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25176 Thesis (PhD)--Macquarie University, Faculty of Science, Dept. of Biological Sciences, 2011. 2013-04-12T06:50:09.940Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25137 Rodents are said to have two different navigational systems, a map-like locale system and a route-based taxon system consisting of sensorimotor routines such as beaconing and turns at appropriate stimulus conditions (motor routines). Ants on the other hand are not known for map-like navigation, and seem to get by with a repertoire of taxon-like strategies. I review how this repertoire serves ants in making up for the lack of a locale system. Path integration — keeping track of the straight-line distance and direction from the starting point — operates continuously in the background, and can be called upon as necessary, or relied on in habitats in which no useful visual cues are available. Crucial to the power of a taxon-like repertoire is using the full panoramic visual context, both to guide the operation of strategies (context-modulated servomechanisms) and to guide navigation directly. The entire repertoire is backed up by systematic search strategies. I end with some reflections on the power of taxon-like strategies. 2013-04-11T11:23:10.279Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25143 3 page(s) 2013-04-11T11:22:57.910Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:16897 1 page(s) 2013-04-10T05:23:03.792Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25071 Plants have evolved multiple layers of defence responses to pathogens. A first line of defence is the recognition and response to common pathogen-associated molecular patterns. Plants also exhibit pathogen-specific responses, which are mediated by expression of resistance genes (R-genes). R-gene products effectively block disease progression. A significant plant pathogen, which causes Myrtle Rust, has spread rapidly along the east coast of Australia since its first identification on the NSW Central Coast in 2010. This incursion is of concern due to the dominance of the Myrtaceae family in Australian vegetation. The recently published genome of Eucalyptus grandis has provided a valuable resource for the identification of potential resistance genes in this important Australian genus. In this study a search was conducted against the E. grandis genome for one important class of R-genes that incorporate nucleotide binding sites and leucine-rich repeat protein domains (NB-LRR). Predicted NB-LRR coding sequences were identified and analysis of the coding sequences revealed 11 gene models within the E. grandis genome. Scrutiny of these gene models, through E. grandis peptide homologues, identified a further 412 genes which contained both NB and LRR domains. The identification of these R-genes may provide researchers with a targeted approach to defence response studies to Myrtle Rust and other pathogens in E. grandis. 2013-04-08T13:29:09.630Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25090 The biological concept of stress originated in mammals, where a “General Adaptation Syndrome” describes a set of common integrated physiological responses to diverse noxious agents. Physiological mechanisms of stress in mammals have been extensively investigated through diverse behavioral and physiological studies. One of the main elements of the stress response pathway is the endocrine hypothalamo-pituitary-adrenal (HPA) axis, which underlies the "fight-or-flight" response via a hormonal cascade of catecholamines and corticoid hormones. Physiological responses to stress have been studied more recently in insects: they involve biogenic amines (octopamine, dopamine), neuropeptides (allatostatin, corazonin) and metabolic hormones (adipokinetic hormone, diuretic hormone). Here, we review elements of the physiological stress response that are or may be specific to honey bees, given the economical and ecological impact of this species. This review proposes a hypothetical integrated honey bee stress pathway somewhat analogous to the mammalian HPA, involving the brain and, particularly, the neurohemal organ corpora cardiaca and peripheral targets, including energy storage organs (fat body and crop). We discuss how this system can organize rapid coordinated changes in metabolic activity and arousal, in response to adverse environmental stimuli. We highlight physiological elements of the general stress responses that are specific to honey bees, and the areas in which we lack information to stimulate more research into how this fascinating and vital insect responds to stress. 2013-04-08T13:27:34.532Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25121 67 page(s) 2013-04-08T13:21:46.236Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25045 Although the major features of the evolution of life have shaped the flora and fauna on whichever continent one explores, each has its own peculiarities. These are largely because of differences in each continent’s tectonic and climatic history, coupled with the timing of evolutionary events. So, in its own way, each continent is unique. But of all the continents, Australia is special, at least in part because of its recent relative isolation from other large continental masses—an isolation that is only now coming to an end. The changing biosphere has also had a profound effect on the atmosphere, hydrosphere and lithosphere. 2013-04-02T23:22:09.476Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:25046 Reward seeking is a major motivator and organizer of behavior, and animals readily learn to modify their behavior to more easily obtain reward, or to respond to stimuli that are predictive of reward. Here, we compare what is known of reward processing mechanisms in insects with the well-studied vertebrate reward systems. In insects almost all of what is known of reward processing is derived from studies of reward learning. This is localized to the mushroom bodies and antennal lobes and organized by a network of hierarchically arranged modulatory circuits, especially those involving octopamine and dopamine. Neurogenetic studies with Drosophila have identified distinct circuit elements for reward learning, "wanting," and possibly "liking" in Drosophila, suggesting a modular structure to the insect reward processing system, which broadly parallels that of the mammals in terms of functional organization. 2013-04-02T23:22:07.449Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:22888 8 page(s) 2013-03-28T02:27:43.581Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24954 Honey bee dance communication is a classic form of animal behavior, with over 70 years of intense study. In this chapter, we first discuss conceptually how it is possible to dissect dance communication into simpler behavioral modules for neurogenomics analysis, based on information from prior ethological studies of dance behavior and a rapidly advancing functional analysis of the insect brain. We then review recent studies that have used this conceptual approach and new genomic tools to begin to explore neurogenomic and neurochemical aspects of dance communication, highlighting the following findings. Comparative transcriptomic studies of specific brain regions across Apis species that differ in dance behavior have implicated genes involved in the geotactic and odometric elements of dance, and genes involved in learning and memory systems and the circadian clock as important modulators of dance output. This research also has identified distinct patterns of gene expression in different brain regions that provide additional hints about the regulation of dance behavior. Pharmacological studies with octopamine and related compounds have demonstrated the role of the reward system in modulating the likelihood that a bee will dance upon returning from a foraging trip. The results of these early studies provide a foundation for a more comprehensive molecular dissection of dance behavior and suggest that the mechanisms regulating dance communication involve evolutionary reuse and adaptation of neuromolecular systems that control elements of solitary behavior. 2013-03-28T02:23:15.339Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24976 The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Konservat-Lagerstäette from the north coast of Kangaroo Island, South Australia, is by far the best preserved and taxonomically diverse Burgess Shale-type fauna in Australia. It occurs mainly within dark grey to black laminated mudstone in the basal 10 metres of the Emu Bay Shale, the base of which is a sequence boundary. Interbedded structureless fine sandstone horizons up to 20 cm thick are interpreted as mass flow or storm deposits; there is evidence of syndepositional faulting and rapid deposition. The sediments were derived from an uplifted Precambrian land mass a short distance to the northwest. There is no sign of bioturbation thus suggesting anoxic conditions immediately below the sediment-water boundary. The abundance of fossils and trace element geochemical data indicate that the overlying water column was oxic with a sharp redox boundary at the sediment-water interface that was possibly maintained by mat-forming cyanophytes thus suggesting clear, relatively shallow water. There were at least two preservational pathways: pyritization and phosphatization. The trilobites Estaingia bilobata and Redlichia takooensis (up to 25 cm long) dominate the fossil assemblage of over 50 taxa. Other trilobites are rare and represent vagrants. Recent work includes descriptions of the bivalved arthropods Isoxys and Tuzoia, two new nektaspid arthropods (Emucaris, Kangacaris), a new leanchoiliid megacheiran arthropod (Oestokerkus) and a new palaeoscolecid. Other fossils include Myoscolex, demosponges, a vetulicolian, an odontogriphid, hyoliths, brachiopods, numerous problematic taxa, and well preserved eyes of an unknown arthropod plus those of Anomalocaris. 2013-03-28T02:22:34.904Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24989 Martin Glaessner is best known for his work on the Ediacara biota of South Australia, but he also played a key role in documenting the early Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstaette on Kangaroo Island. Glaessner was the first to describe some of the more common soft-bodied species, including the arthropods Isoxys communis and Tuzoia australis, the priapulid Palaeoscolex antiquus, and the problematic taxa Myoscolex and Vetustovermis. Recent excavations by us at Buck Quarry have revealed a surprising diversity, with over 50 species now known. The EBS biota is dominated by euarthropods (>50%), with the remaining species diversity comprising various other ecdysozoans (e.g., priapulids and a lobopodian), sponges, molluscs, brachiopods, a polychaete annelid, and a variety of problematic forms. Although the constituent taxa represent a typical Burgess-Shale-type (BST) fauna, EBS fossils display a range of taphonomic modes that are otherwise rare in most other BST deposits. For example, recently documented arthropod eyes, including those of Anomalocaris, show two distinct modes, preserved as iron oxide (after pyrite) and calcium phosphate, demonstrating that disparate styles of early diagenetic mineralization can replicate the same type of extracellulartissue within a single BST deposit. This contrasts with many other BST deposits wherein recalcitrant tissues such as cuticle typically preserve as featureless carbon films. This demonstrates that the prevalence of early diagenetic mineralization of soft tissues seen in EBS fossils can provide much better anatomical resolution in some instances than other deposits around the world. 2013-03-28T02:22:12.929Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24800 Microbial pathogens are ancient selective agents that have driven many aspects of multicellular evolution, including genetic, behavioural, chemical and immune defence systems. It appears that fungi specialised to attack insects were already present in the environments in which social insects first evolved and we hypothesise that if the early stages of social evolution required antifungal defences, then covariance between levels of sociality and antifungal defences might be evident in extant lineages, the defences becoming stronger with group size and increasing social organisation. Thus, we compared the activity of cuticular antifungal compounds in thrips species (Insecta: Thysanoptera) representing a gradient of increasing group size and sociality: solitary, communal, social and eusocial, against the entomopathogen Cordyceps bassiana. Solitary and communal species showed little or no activity. In contrast, the social and eusocial species killed this fungus, suggesting that the evolution of sociality has been accompanied by sharp increases in the effectiveness of antifungal compounds. The antiquity of fungal entomopathogens, demonstrated by fossil finds, coupled with the unequivocal response of thrips colonies to them shown here, suggests two new insights into the evolution of thrips sociality: First, traits that enabled nascent colonies to defend themselves against microbial pathogens should be added to those considered essential for social evolution. Second, limits to the strength of antimicrobials, through resource constraints or self-antibiosis, may have been overcome by increase in the numbers of individuals secreting them, thus driving increases in colony size. If this is the case for social thrips, then we may ask: did antimicrobial traits and microbes such as fungal entomopathogens play an integral part in the evolution of insect sociality in general? 2013-03-18T04:01:49.568Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24801 An extensive data set on net primary production (NPP) in China's forests is analysed with the help of two simple theoretically derived models based on the light use efficiency (LUE) and water use efficiency (WUE) concepts, respectively. The two models describe the data equally well, but their implied responses to [CO₂] and temperature differ substantially. These responses are illustrated by sensitivity tests in which [CO₂] is kept constant or doubled, temperatures are kept constant or increased by 3.5 K, and precipitation is changed by ±10%. Precipitation changes elicit similar responses in both models. But NPP in South China, especially, is reduced by warming in the LUE model, whereas it is increased in the WUE model. The [CO₂] response of the WUE model is much larger than that of the LUE model. It is argued that the two models provide upper and lower bounds for this response, with the LUE model more realistic for forests. The differences between the two models illustrate some potential causes of the large differences (even in sign) in the global NPP response of different global vegetation models to temperature and [CO₂]. 2013-03-18T04:01:49.157Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24802 Providing food to developing offspring is beneficial for offspring but costly for carers. Understanding patterns of provisioning thus yields important insights into how selection shapes (allo-) parental care strategies. Broadly, offspring development will be influenced by three components of provisioning (prey type, size and delivery rate). However, all three variables are rarely considered simultaneously, leading to suggestions that the results of many studies are misleading. Additionally, few studies have examined the provisioning strategies of breeders and non-breeding helpers in obligate cooperative breeders, wherein reproduction without help is typically unsuccessful. We investigated these components of provisioning in obligately cooperative chestnut-crowned babblers (Pomatostomus ruficeps). Prey type was associated with size, and delivery rate was the best predictor of the overall amount of food provided by carers. As broods aged, breeders and helpers similarly modified the relative proportion of different prey provided and increased both prey size and delivery rate. Breeding females contributed less prey than male breeders and adult helpers, and were the only carers to load-lighten by reducing their provisioning rates in the presence of additional carers. While our results suggest that breeders and helpers follow broadly comparable provisioning rules, they are also consistent with the idea that, in obligately cooperative species, breeding females benefit more from conserving resources for future reproduction than do helpers which have a low probability of breeding independently. 2013-03-18T04:01:45.951Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24834 The Welcome Swallow Hirundo neoxena is an aerial passerine that specialises on flying arthropod prey, which it captures on the wing. In September 2011, I observed an adult Swallow capture a small live fish from a pool in a tributary of the Lane Cove River, New South Wales. This is believed to be the first documentation of a Welcome Swallow catching a fish and one of the few observations of the capture of a fish by a member of the family Hirudinidae. 2013-03-18T04:00:35.779Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24773 Background Most members of the serpin family of proteins are potent, irreversible inhibitors of specific serine or cysteine proteinases. Inhibitory serpins are distinguished from members of other families of proteinase inhibitors by their metastable structure and unique suicide-substrate mechanism. Animal serpins exert control over a remarkable diversity of physiological processes including blood coagulation, fibrinolysis, innate immunity and aspects of development. Relatively little is known about the complement of serpin genes in plant genomes and the biological functions of plant serpins. Results A structurally refined amino-acid sequence alignment of the 14 full-length serpins encoded in the genome of the japonica rice Oryza sativa cv. Nipponbare (a monocot) showed a diversity of reactive-centre sequences (which largely determine inhibitory specificity) and a low degree of identity with those of serpins in Arabidopsis (a eudicot). A new convenient and functionally informative nomenclature for plant serpins in which the reactive-centre sequence is incorporated into the serpin name was developed and applied to the rice serpins. A phylogenetic analysis of the rice serpins provided evidence for two main clades and a number of relatively recent gene duplications. Transcriptional analysis showed vastly different levels of basal expression among eight selected rice serpin genes in callus tissue, during seedling development, among vegetative tissues of mature plants and throughout seed development. The gene OsSRP-LRS (Os03g41419), encoding a putative orthologue of Arabidopsis AtSerpin1 (At1g47710), was expressed ubiquitously and at high levels. The second most highly expressed serpin gene was OsSRP-PLP (Os11g11500), encoding a non-inhibitory serpin with a surprisingly well-conserved reactive-centre loop (RCL) sequence among putative orthologues in other grass species. Conclusions The diversity of reactive-centre sequences among the putatively inhibitory serpins of rice point to a range of target proteases with different proteolytic specificities. Large differences in basal expression levels of the eight selected rice serpin genes during development further suggest a range of functions in regulation and in plant defence for the corresponding proteins. 2013-03-13T09:50:42.252Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24682 The freshwater habitats (mires, streams, lakes, pools and wallows) on sub-Antarctic Marion Island were examined for invertebrates. Sixty-eight species were found, including 45 new records for the Island. Of these 56 were bona fide aquatic invertebrates, the rest being terrestrial or brackish interlopers that had fallen or been blown into the water. The aquatic species include five platyhelminthes, a gastrotrich, three tardigrades, 28 rotifers, six nematodes, two annelids and 11 arthropods. Most are familiar species that have been recorded on other sub-Antarctic islands. The invertebrate faunas of the various freshwater habitats were basically similar in species composition, with the abundances of particular species dependent upon the water body's size, distance from the sea and degree of eutrophication resulting from seal and seabird manuring. 2013-03-12T09:42:13.100Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24688 1 page(s) 2013-03-12T09:42:03.567Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24706 1 page(s) 2013-03-12T09:41:36.967Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24716 1 page(s) 2013-03-12T09:41:23.607Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24744 6th International Brachiopod Congress Melbourne, February 2010. Excursion E4. 2013-03-12T09:40:43.285Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24752 13 page(s) 2013-03-12T09:40:23.727Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24662 1 page(s) 2013-03-11T21:10:46.611Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24671 It is well demonstrated that the responses of plants to elevated atmospheric CO₂ concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO₂ and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate, shoot biomass, root biomass, symbiotic nitrogenase activity, and leaf N content. Symbiotic nitrogenase activity was determined by the C₂H₂ reduction method. Elevated CO₂ enhanced photosynthesis and shoot biomass by 83% and 25%, respectively, and the enhancement of shoot biomass was significant only at a high N concentration. In addition, the photosynthetic capacity of C. microphylla did not show down-regulation under elevated CO₂. Elevated CO₂ had no significant effect on root biomass, symbiotic nitrogenase activity and leaf N content. Under elevated CO₂, N addition stimulated photosynthesis and shoot biomass. By contrast, N addition strongly inhibited symbiotic nitrogenase activity and slightly increased leaf N content of C. microphylla under both CO₂ levels, and had no significant effect on root biomass. The effect of elevated CO₂ and N addition on C. microphylla did not show interannual variation, except for the effect of N addition on leaf N content. These results indicate that shoot growth of C. microphylla is more sensitive to elevated CO₂ than is root growth. The stimulation of shoot growth of C. microphylla under elevated CO₂ or N addition is not associated with changes in N2-fixation. Additionally, elevated CO₂ and N addition interacted to affect shoot growth of C. microphylla with a stimulatory effect occurring only under combination of these two factors. 2013-03-11T21:10:28.963Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24478 Dailyatia is an enigmatic tommotiid genus endemic to lower Cambrian successions of East Gondwana (Australia and Antarctica). The plethora of sclerite mor photype variation has made the taxonomy of the genus highly problematic. Recovery of 6750 Dailyatia sclerites from more than 20 separate measured stratigraphic sections and 100+ spot localities from the Flinders Ranges (Arrowie Basin) of South Australia reveals hither to unappreciated species-level diversity. Superbly preserved new material provides intriguing new morphological and ultrastructural data -- including the presence of bizzare honeycomb-like apicies and a possible partial scleritome fragment. An elongate, tapering tube attached to the inner surface of a few, rare sclerites appears to match sclerite growth but extends well beyond the margin of the sclerite. This possible pathological response to parasitism or internal shell damage reveals important new information about sclerite growth and functional morphology. Detailed investigation indicates that all 5 species of Dailyatia have discreet, and in some cases, mutually exclusive stratigraphic ranges -- potentially important for regional biostratigraphic subdivision of Hawker Group rocks in the Arrowie Basin. The new palaeobiological and biostratigraphic information about Dailyatia (and other camenellans) will help decipher the complex timing of character assembly and morphological transformations from a deep root within the lophotrochozoan phylogenetic tree. 2013-03-06T08:04:44.393Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24479 Systematic acid digestion of samples derived from 24 separate stratigraphic sections measured through thick carbonate dominated lower Cambrian successions in the Flinders Ranges (Arrowie Basin) reveals an unexpectedly rich diversity (c. 25 taxa) of well-preserved bradoriid arthropods. The new assemblages occur across a broad spectrum of biofacies including shallow water stromatolitic facies, archaeocyath-cryptalgal bioherms and carbonate slope facies. The oldest known bradoriid taxon (Liangshanella circumbolina) from East Gondwana occurs 20 m below the FAD of the zonal trilobite Abadiella huoi in the lower Cambrian Ajax and Wirrapowie limestones of the Flinders Ranges, South Australia. This occurrence suggests a lower Cambrian (Series 2, Stage 3) age for the earliest bradoriids in Australia. The recognition of distinct bradoriid assemblages associated with the Abadiella huoi (Atdabanian), Pararaia tatei, P. bunyerooensis and P. janeae (all Botoman) trilobite biozones in South Australia indicates great potential for future regional biostratigraphic correlation. An updated quantitative biogeographic analysis utilising new unpublished taxonomic data from the lower Cambrian of South Australia highlights the strong endemism displayed by early Cambrian bradoriid communities in East Gondwana -- but the presence of a few previously unreported cosmopolitan taxa strengthens the close faunal affinities with South China, Antarctica and Siberia. 2013-03-06T08:04:40.449Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24490 Acid mine drainage is a significant environmental hazard. Highly acidified water in affected sites causes a range of environmental issues including accumulation of heavy metals, loss of biodiversity and, particularly in sites with coal-mining history, greenhouse gas emissions. In acid mine drainage sites related to coal mining, methane and carbon dioxide are formed by the microbial decomposition of coal under anaerobic conditions. To date, much of the work on acid mine drainage has focused on the microbiology and biogeochemistry of the surface water, and little is known about the microbiological processes occurring in the anaerobic sediments associated with these environments. Therefore, to better understand these processes, we have used Illumina-based metagenomics to examine the microbial diversity of the anaerobic sediment zones in a coal-fueled acid mine drainage system in the Hunter Valley, NSW, Australia. The microbial community composition of these environments along with the physiological potential of the organisms in these communities will be discussed. 2013-03-06T08:04:17.849Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24501 In sclerophylls, photosynthesis is particularly strongly limited by mesophyll diffusion resistance from substomatal cavities to chloroplasts (rm), but the controls on diffusion limits by integral leaf variables such as leaf thickness, density, and dry mass per unit area and by the individual steps along the diffusion pathway are imperfectly understood. To gain insight into the determinants of rm in leaves with varying structure, the full CO₂ physical diffusion pathway was analysed in 32 Australian species sampled from sites contrasting in soil nutrients and rainfall, and having leaf structures from mesophytic to strongly sclerophyllous. rm was estimated based on combined measurements of gas exchange and chlorophyll fluorescence. In addition, rm was modelled on the basis of detailed anatomical measurements to separate the importance of different serial resistances affecting CO₂ diffusion into chloroplasts. The strongest sources of variation in rm were Sc/S, the exposed surface area of chloroplasts per unit leaf area, and mesophyll cell wall thickness, tcw. The strong correlation of rm with tcw could not be explained by cell wall thickness alone, and most likely arose from a further effect of cell wall porosity. The CO₂ drawdown from intercellular spaces to chloroplasts was positively correlated with tcw, suggesting enhanced diffusional limitations in leaves with thicker cell walls. Leaf thickness and density were poorly correlated with Sc/S, indicating that widely varying combinations of leaf anatomical traits occur at given values of leaf integrated traits, and suggesting that detailed anatomical studies are needed to predict rm for any given species. 2013-03-06T08:04:02.911Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24500 During the Mid Ordovician (Darriwilian) marine sand- and siltstones were deposited in an epicontinental sea penetrating profoundly into the Australian continent. The Middle Darriwilian Stairway Sandstone has, for the first time, been sampled stratigraphically to track marine benthic biodiversity in this shallow water regime in Eastern Gondwana. The fauna is dominated by richly diverse bivalves, with the remaining fauna comprising trilobites, brachiopods, rostroconchs, gastropods, cephalopods, monoplacophorans and rare bryozoans and possible sponges. Trace fossils are abundant and have recently been documented. Bivalves dominate regardless of subfacies type, varying from siltstone, calc-arenite, quartzite to dolomitic calc-sandstone. Brachiopods and trilobites, represented in great numbers in the remaining part of the fauna, typically occur in the silt dominated intervals. Filter feeders including bivalves, brachiopods and rostroconchs constitute a large proportion of the fauna. The Stairway Sandstone was deposited in near shore environment, with relatively high energy conditions. The filter feeders have adapted to these relatively hostile palaeoenvironmental conditions, whereas many other filter feeder communities tend to prefer deeper- and calmer water conditions. The macrofossils from the Stairway Sandstone display a high degree of endemism at species level (at least 75%). The rare species, in common with faunas from other nearby basins, are generally cosmopolitan taxa. New species of trilobites and brachiopods have now been described from the material. 2013-03-06T08:04:02.717Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24510 Brachiopods dominated the benthic Palaeozoic marine realm, both in terms of relative abundance and also species diversity. The Ordovician represented a pivotal period for brachiopods, with the phylum under taking a spectacular surge in biodiversity driven by an exponential increase in numbers at family, genus and species levels. However, brachiopods had a significant history prior to the Ordovician, with the majority of higher-level taxa already established during the Cambrian 'explosion'. Calcareous rhynchonelliform brachiopods tended to be a minor and relatively short-lived component of these Cambrian communities and there is a significant time lag between their appearance in the early Cambrian and the explosion of genera in the Ordovician. The relationship of many Cambrian rhynchonelliform brachiopods is poorly understood, with many genera displaying a combination of morphological features that are taxonomically confusing. Yet, the study of middle Cambrian -- early Tremadocian brachiopods is pivotal to fill the interval between the two major radiation phases in the early Palaeozoic. Here we present a parsimony analysis of a wide selection of Cambrian and Ordovician brachiopod genera with a particular focus on the evolution and phylogeny of the Billingsellida, a group considered by many to represent the ancestral stock of several Ordovician brachiopod lineages. The analyses portray the polytoechioids as derived billingselloids separate from the clitambonitoids that form a sister group. The enigmatic Roanella is interpreted as ancestral to the clitambonitoids within a new monogeneric family, Roanellidae nov. and the recently reappraised clitambonitoid Arctohedra is interpreted as a basal member of the entire order Billingsellida. 2013-03-06T08:03:41.344Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24526 During the critical period of expansive biotic radiation in the early Cambrian, Antarctica and southern Australia where sutured together near the equator forming East Gondwana. The rocks deposited during this interval provide ample evidence of a shared geological, palaeontological and palaeogeographic heritage. However, there has been almost no previous systematic sampling of lower Cambrian fossiliferous successions forphosphatic shelly fossils, which have proven so important in providing a chronological framework for understanding the early evolution, ecology and biogeography of bilaterian animals. The retrieval of such faunas provide raw material for investigating the morphological diversity and phylogeny of early (stem group) bilaterians as well as provide a means to under take detailed biostratigraphic correlation between lower Cambrian sequences packages in Antarctica and South Australia. To this end, detailed sampling along stratigraphic sections measured through autochthonous, fault repeated, lower Cambrian carbonate succession of shallow water carbonate platform complete with peri-reefal bioherms in the Shackleton Limestone and overlying carbonate ramp and slope transition in the Holyoake and lower Starshot Formations has produced a moderately diverse fauna of shelly fossils including chancelloriids, sponge spicules, helcionellid molluscs, cupitheciids, hyolithelminth tubes, echinoderm ossicles and the acrotretoid brachiopod species Vandalotreta djagoran, as well as the obolide Eodicellomus elkaniiformis. This newly discovered fauna provides direct correlation to the Wirrealpa and Aroona Creek Limestones in the Flinders Ranges (Arrowie Basin), South Australia and suggests a Toyonian (Cambrian Series 2, Stage 4) age for the upper Shackleton Limestone in the Holyoake Range. 2013-03-06T08:03:13.455Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24562 CO₂-enrichment experiments consistently show that rooting depth increases when trees are grown at elevated CO₂ (eCO₂), leading in some experiments to increased capture of available soil nitrogen (N) from deeper soil. However, the link between N uptake and root distributions remains poorly represented in forest ecosystem and global land-surface models. Here, this link is modeled and analyzed using a new optimization hypothesis (MaxNup) for root foraging in relation to the spatial variability of soil N, according to which a given total root mass is distributed vertically in order to maximize annual N uptake. MaxNup leads to analytical predictions for the optimal vertical profile of root biomass, maximum rooting depth, and N-uptake fraction (i.e., the proportion of plant-available soil N taken up annually by roots). We use these predictions to gain new insight into the behavior of the N-uptake fraction in trees growing at the Oak Ridge National Laboratory free-air CO₂-enrichment experiment. We also compare MaxNup with empirical equations previously fitted to root-distribution data from all the world's plant biomes, and find that the empirical equations underestimate the capacity of root systems to take up N. 2013-03-06T08:01:54.168Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24593 Although many Quaternary records have allowed the study of major glacial-interglacial change in the Southern Ocean, Holocene records from deep-sea cores are few and far between and are currently limited to the South Atlantic. Low sedimentation rates combined with deep seafloors, and the high-nutrient, low-chlorophyll nature of the Southern Ocean are all in part responsible for the lack of decadal-to-centennial resolution records in the open-ocean environment. Our study is focused on an array of sedimentological, micropalaeontological and geochemical analyses conducted on the first open-ocean, high-resolution core study of Quaternary-Holocene sea-ice variability in the Southeast Indian Ocean; Eltanin piston core 27-23. In this presentation the results of sea ice estimates derived from diatom remains and tied to other physical and geological proxies will reveal the change from a sea-ice covered glacial maximum and deglacial transition through to the modern day. We report evidence of several Holocene ice edge advance episodes out to 59 S, inclusive of the Antarctic Climatic Reversal. The addition of this record to existing, lower-resolution, sea-ice histories from regional cores MD88-787 and SO136-111 and in context to modern oceanographic fronts enables scenarios of regional palaeoceanographic change to be refined. 2013-03-06T08:00:43.313Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24348 Trait variation in plant communities is thought to be constrained by two opposing community assembly processes operating at discrete spatial scales: habitat filtering and limiting similarity between coexisting species. Filtering processes cause convergence in ecological strategy as species are excluded from unsuitable sites, whilst limiting similarity leads to the divergence of trait values between co-occurring species in order to alleviate competition for finite resources. Levels of alpha (within-site) and beta (among-site) trait variation can be indicative of the strength of these community assembly processes. We used trait-gradient analysis to explicitly compare evidence of community assembly patterns in lianas (woody vines) and trees. These two growth forms exhibit striking differences in carbon capture and regeneration strategies, yet trait-based mechanisms that maintain their coexistence remain understudied. Using data for four functional traits leaf mass per area, leaf nitrogen content (Nmass), leaf area and seed mass we partitioned interspecific trait variation in lianas and trees into alpha and beta components. Our three key findings were: 1) lianas and trees exhibit divergent patterns of trait-based habitat filtering, due to differences in the relationship between leaf size and the other three traits examined (LMA, Nmass and seed mass), 2) on average, liana species possess smaller seeds, lower LMA and higher Nmass than do trees, but there was no clear difference in leaf area between the two growth forms, and 3) soil fertility was correlated with trait variation (leaf area, seed mass) at the site-level in trees, but not in lianas. These results provide evidence that dominant growth forms can be filtered into the same habitat on the basis of different combinations of traits. Our findings have important implications for community assembly and co-existence theory and for more pragmatic matters such as using trait-based principles to inform community restoration. 2013-02-27T05:25:43.708Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24349 Whether non-native species proliferate to pest status can depend on top-down control from native predators. Among epifaunal molluscs, the shell serves as a main line of anti-predator defence and shell strength may determine the ease with which generalist predators can penetrate prey. We assessed whether, in eastern Australia, the faster growth of the non-native Pacific oyster, Crassostrea gigas, than that of the native Saccostrea glomerata comes at the cost of reduced investment in shell thickening, rendering the non-native oyster more susceptible to a generalist predator, the muricid gastropod Morula marginalba. Laboratory tests confirmed that among larger (>50-mm shell height) oysters, the shells of C. gigas were weaker than those of similar-sized S. glomerata. There were, however, no differences in shell strength or thickness between smaller S. glomerata and C. gigas of the size consumed by M. marginalba. In the absence of shell-strength differences among smaller oysters, M. marginalba preferentially consumed native over non-native oysters. When, however, M. marginalba had no choice of prey item, C. gigas was consumed at the same rate as the native oyster. Our results add to growing evidence that the invasion of C. gigas in eastern Australian estuaries is, at present, causing minimal disruption to trophic relationships. 2013-02-27T05:25:40.099Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24350 The eastern Australian aquifers remain mostly unexplored; however, recent surveys suggest that there could be substantial levels of subterranean biodiversity hidden in these aquifers. Groundwater fauna (stygofauna) is often characterised by short-range endemism. Furthermore, high levels of cryptic species, and lack of formal taxonomic descriptions and taxonomic expertise for many of the groups demand innovative approaches for assessing subterranean biodiversity. Here we evaluate the potential of using DNA barcoding as a rapid biodiversity assessment tool for the subterranean groundwater fauna of New South Wales, Australia. We experienced low amplification success using universal and more taxon-specific primers for PCR amplification of the barcoding gene (COI) in a range of crustacean stygofauna. Sequence comparisons of the most commonly used COI universal primers in selected crustacean taxa revealed high levels of variability. Our results suggest that successful amplification of the COI region from crustacean stygofauna is not straightforward using the standard 'universal' primers. We propose that the development of a multiprimer (taxon specific) and multigene approach for DNA barcode analyses, using next-generation sequencing methodologies, will help to overcome many of the technical problems reported here and provide a basis for using DNA barcoding for rapid biodiversity assessments of subterranean aquatic ecosystems. 2013-02-27T05:25:39.883Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24396 Increasing atmospheric CO₂ concentration is causing increased absorption of CO₂ by the world’s oceans, in turn driving a decline in seawater pH and changes in ocean carbonate chemistry that are collectively referred to as ocean acidification. Evidence is accumulating to suggest ocean acidification may directly or indirectly affect many marine organisms and ecosystems, some of which may also hold significant social and economic value to the Australian community. This report aims to provide a brief overview of the current state of scientific knowledge regarding the process of ocean acidification; current and future projected levels of ocean acidification; and, observed and projected impacts of current and future predicted levels of ocean acidification on marine organisms and ecosystems in the region. This report also briefly discusses potential social and economic implications, policy challenges, and the key knowledge gaps needing to be addressed. 2013-02-27T05:23:25.365Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24400 2 page(s) 2013-02-27T05:23:12.700Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24404 This article is a revision of the previous edition article by Sean R. Connolly, volume 3, pp 53–62, ©2001, Elsevier Inc. 2013-02-27T05:23:08.298Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24434 Second Workshop of the Palaeoclimate Modelling Intercomparison Project Phase 3;Crewe, United Kingdom, 6-11 May 2012 The Palaeoclimate Modelling Intercomparison Project (PMIP) is an international initiative endorsed by the World Climate Research Programme, the International Geosphere-Biosphere Programme, and the Past Global Changes Project. Its objective is to provide a coherent framework to assess climate models and investigate climate dynamics on the basis of paleoclimate evidence. To this end, PMIP provides protocols for simulations of a set of past epochs with climate models, centralizes model output and facilitates access to it, and organizes syntheses of paleoclimate observations for model evaluation. 2013-02-27T05:20:25.087Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24286 1 page(s) 2013-02-19T18:11:46.152Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24210 The monotreme genus Zaglossus, the largest egg-laying mammal, comprises several endangered taxa today known only from New Guinea. Zaglossus is considered to be extinct in Australia, where its apparent occurrence (in addition to the large echidna genus Megalibgwilia) is recorded by Pleistocene fossil remains, as well as from convincing representations in Aboriginal rock art from Arnhem Land (Northern Territory). Here we report on the existence and history of a well documented but previously overlooked museum specimen (skin and skull) of the Western Long-Beaked Echidna (Zaglossus bruijnii) collected by John T. Tunney at Mount Anderson in the West Kimberley region of northern Western Australia in 1901, now deposited in the Natural History Museum, London. Possible accounts from living memory of Zaglossus are provided by Aboriginal inhabitants from Kununurra in the East Kimberley. We conclude that, like Tachyglossus, Zaglossus is part of the modern fauna of the Kimberley region of Western Australia, where it apparently survived as a rare element into the twentieth century, and may still survive. 2013-02-18T06:32:45.855Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24165 Patterns of settlement and postsettlement mortality determine the distribution and abundance of sessile marine organisms. In mangrove forests and on rocky shores of eastern Australia, the Sydney rock oyster, Saccostrea glomerata, displays a pattern of declining abundance with increasing tidal elevation that might be related to or independent of the tidal elevation gradient in the substrate (bare, dead conspecifics, live conspecifics) available for attachment. We conducted parallel manipulative experiments on a rocky shore and in a mangrove forest to assess (1) the relative importance of tidal elevation and substrate type (bare, live oysters, or dead oysters) in determining the spatial distribution of new (<1 mm) S. glomerata recruits and (2) the contribution of settlement and postsettlement processes in setting patterns of spatial variation in established oyster populations. Patches of habitat with either live oysters, dead oysters, or no conspecifics were established at 3 tidal elevations at each site, and natural settlement and postsettlement mortality were monitored through time. At each site, and regardless of the substrate provided, we detected a similar pattern of fewer new S. glomerata recruits and greater postsettlement mortality on the high intertidal shore rather than the mid or low intertidal shore. Substrate type, by contrast, influenced the abundance of new recruits, but not subsequent postsettlement mortality. Consequently, over a period of months, direct effects of tidal elevation rather than effects of substrate type determined spatial patterns of oyster recruitment on the rocky shore and in the mangrove. Consequently, we documented that on a rocky shore and in a mangrove forest, settlement and early postsettlement mortality vary similarly across tidal elevation gradients and substrate types to determine the distribution of S. glomerata. 2013-02-12T04:40:23.303Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24164 Silica is ubiquitous in plants and can constitute up to 10% of plant dry mass, varying with phylogeny and soil silicon availability. Plant silicon is an important alleviator of abiotic (salinity, heavy metal, drought) and biotic (herbivore and fungal pathogen) stress. As well as playing an important role in reducing the impact of abiotic stresses, silicon may be an alternative to carbon-based and other chemical defences. Knowledge of silicon function is predominantly derived from agricultural species and model systems. We investigated the abundance and role of plant silicon at a community level by comparing leaf silicon concentration with defence chemicals, carbon compound concentrations and invertebrate assemblages in vegetation communities from two different soil types with contrasting levels of plant available silicon. We found that the concentrations of silicon in the leaves did not reflect the silicon availability in the soil at a community level. The leaf silica concentration range in the vegetation communities was comparable to other diverse communities reported in the literature, suggesting that the species rather than the environment determine leaf silica concentration. Across sites, leaf silica concentration was significantly negatively correlated with concentrations of carbon, total phenols and weakly with tannins but not with other measured defence compounds. Leaf silica concentration was also negatively correlated with Coleoptera abundance, but not the abundance of any other invertebrate groups measured. Our results suggest that tradeoffs exist between phenolic- and tannin-based defences and provide evidence that leaf silicification may be a more effective defence against some chewing herbivore groups than others. 2013-02-12T04:40:22.865Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24171 Two mathematical laws of behavior derived from work on vertebrate ­animals were tested in honey bees in my research. One law concerned the ubiquitous phenomenon of generalization in learning. An animal obtaining a reward for a response to one stimulus will often make that response to similar but discriminably different stimuli. Under a suitably ideal characterization, generalization gradients ought to come out exponential in shape (Shepard RN, Science 237:1317–1323, 1987). In spatial generalization in honey bees, this prediction was upheld in a number of different studies. A second law concerned the weighting of different and conflicting evidence. A piece of evidence is supposed to be weighted by its recency, with more recent evidence given higher weight (Devenport L, Hill T, Wilson M, Ogden E, J Exp Psychol Anim Behav Process 23:450–460, 1997). With the passage of time since the last evidence was obtained, overall profitability of a ‘patch’ rather than recency of profits should dominate. Tests with honey bees failed to uphold this law, instead finding circadian modulation of preferences, with ‘patch’ preference highest at the circadian time at which reward was obtained on the previous (training) day. I attempted a speculative reformulation in terms of modulation of preferences according to different oscillators. 2013-02-12T04:40:16.115Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24039 Current estimates of gross primary productivity (GPP) of the terrestrial biosphere vary widely, from 100 to 175 Gt C year⁻¹. Ecosystem GPP cannot be measured directly, and is commonly estimated using models. Among the many parameters in those models, three leaf parameters have strong influences on the modelled GPP: leaf mass per area, leaf lifespan and leaf nitrogen concentration. The first two parameters affect the modelled canopy leaf area and the last two determine the maximal leaf photosynthetic rate. Ecological studies have firmly established that these three parameters are significantly correlated at regional to global scales, but this knowledge is yet to be used in predicting global GPP. We hypothesize that incorporating multi-trait covariance can reduce uncertainties of model predictions in a way likely to provide improved realism. Using the Australian community land surface model (CABLE), we find that correlations among these three parameters reduce the variance among GPP estimates by CABLE by over 20% for shrub, C4 grassland and tundra, and by between 5% and 20% for most other PFTs, as compared with the simulated GPP without considering the correlations. Globally the correlations do not alter the mean but reduce the variance of modeled GPP by CABLE by 28% and result in fewer extremely high or extremely low (and unlikely) global GPP predictions. Therefore correlations among the three leaf parameters, and possibly other parameters, can be used as a significant constraint on the estimates of model parameters or predictions by those models. 2013-02-06T03:42:24.597Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24054 The anchialine system at Bundera sinkhole, Australia, exhibits pronounced hydrogeochemical structure through depth that is reflected in the composition and distribution of the fauna. It is a strongly structured microbial ecosystem the components of which also change with depth and which is dominated by sulfur bacteria and chemolithotrophic microbial classes. 2013-02-06T03:41:59.996Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24065 Contests among individuals over mating opportunities are common across diverse taxa, yet physical conflict is relatively rare. Due to the potentially fatal consequences of physical fighting, most animals employ mechanisms of conflict resolution involving signalling and ritualistic assessment. Here we provide the first evidence of ubiquitous escalated fighting in grasshoppers. The chameleon grasshopper (Kosciuscola tristis) is an Australian alpine specialist, in which males engage in highly aggressive combat over ovipositing females. We describe discrete agonistic behaviours including mandible flaring, mounting, grappling, kicking and biting, and their use depending on the individual's role as challenger or defender. We show that male role predicts damage, with challengers being more heavily damaged than males defending females (defenders). Challengers also possess wider mandibles than defenders, but are similar in other metrics of body size. Our data suggest that fights escalate between males matched in body size and that mandibles are used as weapons in this species. This system represents an exciting opportunity for future research into the evolution of costly fighting behaviour in an otherwise placid group. 2013-02-06T03:41:43.883Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24066 A set of polymorphic loci was characterised using an enrichment library for the Australian alpine specialist, the chameleon grasshopper (Kosciuscola tristis), an atypical grasshopper known for its remarkable temperature-controlled colour change. The number of alleles per locus ranged from three to 20 and observed heterozygosity from 0.16 to 0.76. These are the first microsatellite markers for a non-endangered Australian alpine animal and will inform questions of gene flow across the sky islands of this unique and threatened region. 2013-02-06T03:41:43.209Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24064 A forty-day voyage from Hobart (Australia) to Haifa (Israel) included a visual and acoustic census for cetaceans in the Indian Ocean Sanctuary. One hundred and sixty-three sightings were made, 156 occurring within the Sanctuary. Twelve species were identified. Sperm whales (Physeter macrocephalus) were encountered most frequently (51% of identified encounters), whilst spinner dolphins (Stenella longirostris) were numerically dominant. Other species identified included bottlenose dolphins (Tursiops spp.), short-beaked common dolphin (Delphinus delphis), pan-tropical spotted dolphin (Stenella attenuata), rough-toothed dolphin (Steno bredanensis), Risso's dolphin (Grampus griseus), killer whale (Orcinus orca), short-finned pilot whale (Globicephala macrorhynchus), false killer whale (Pseudorca crassidens), Bryde's whale (Balaenoptera edeni) and Cuvier's beaked whale (Ziphius cavirostris). The most sightings occurred WNW of the Seychelles, east of Somalia, and in the Gulf of Aden and Red Sea. Half of the sperm whale sightings were to the east of Ras Hafun (Somalia), and included adults, subadults and at least one calf. Thirteen hours were spent listening for cetaceans using a towed array whilst the ship was underway. Cetaceans were detected at 78% of the listening stations, with a possible four species recorded (sperm whale, spinner dolphin, pilot whale, bottlenose dolphin). The survey shows the value of platforms of opportunity for studying the pelagic communities of cetaceans in the Indian Ocean Sanctuary. It highlights the need for further research in the northwestern sector where anthropogenic threats are varied and increasing. 2013-02-03T22:23:47.354Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23769 This paper presents improvement technique on linearity of a CMOS double balance Gilbert cell mixer with considerable high conversion gain at low power consumption. The mixer consists of inductive source degeneration in the transconductance stage providing impedance matching to improve linearity of the mixer. The mixer was designed to operate a Radio Frequency (RF) signal of 4GHz, a Local Oscillator frequency (LO) of 3.75GHz, thus providing an Intermediate Frequency (IF) of 0.25GHz. The circuit presents an Input third order Intercept point (IIP3) of +1dBm. A conversion gain of 10.45dB and a single sideband noise of 8dB over the band width. The DC power consumed by the core mixer is 4.5mW. The proposed active mixer design was made in 0.25µm CMOS Silanna process, suitable for wideband applications. 2013-01-31T04:52:42.785Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24001 Process-based models (PBMs) of vegetation function can be used to interpret and integrate experimental results. Water limitation to plant carbon uptake is a highly uncertain process in the context of environmental change, and many experiments have been carried out that study drought limitations to vegetation function at spatial scales from seedlings to entire canopies. What is lacking in the synthesis of these experiments is a quantitative tool incorporating a detailed mechanistic representation of the water balance that can be used to integrate and analyse experimental results at scales of both the whole-plant and the forest canopy. To fill this gap, we developed an individual tree-based model (MAESPA), largely based on combining the well-known MAESTRA and SPA ecosystem models. The model includes a hydraulically-based model of stomatal conductance, root water uptake routines, drainage, infiltration, runoff and canopy interception, as well as detailed radiation interception and leaf physiology routines from the MAESTRA model. The model can be applied both to single plants of arbitrary size and shape, as well as stands of trees. The utility of this model is demonstrated by studying the interaction between elevated [CO₂] (eCa) and drought. Based on theory, this interaction is generally expected to be positive, so that plants growing in eC(a) should be less susceptible to drought. Experimental results, however, are varied. We apply the model to a previously published experiment on droughted cherry, and show that changes in plant parameters due to long-term growth at eCa (acclimation) may strongly affect the outcome of C-a x drought experiments. We discuss potential applications of MAESPA and some of the key uncertainties in process representation. 2013-01-31T04:51:10.090Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24008 Understanding how biogeochemical cycles relate to the structure of ecological communities is a central research question in ecology. Here we approach this problem by focusing on body size, which is an easily measured species trait that has a pervasive influence on multiple aspects of community structure and ecosystem functioning. We test the predictions of a model derived from metabolic theory using data on ecosystem metabolism and community size structure. These data were collected as part of an aquatic mesocosm experiment that was designed to simulate future environmental warming. Our analyses demonstrate significant linkages between community size structure and ecosystem functioning, and the effects of warming on these links. Specifically, we show that carbon fluxes were significantly influenced by seasonal variation in temperature, and yielded activation energies remarkably similar to those predicted based on the temperature dependencies of individual-level photosynthesis and respiration. We also show that community size structure significantly influenced fluxes of ecosystem respiration and gross primary production, particularly at the annual time-scale. Assessing size structure and the factors that control it, both empirically and theoretically, therefore promises to aid in understanding links between individual organisms and biogeochemical cycles, and in predicting the responses of key ecosystem functions to future environmental change. 2013-01-31T04:50:54.407Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:24007 Climatic oscillations during the Pleistocene have greatly influenced the distribution and connectivity of many organisms, leading to extinctions but also generating biodiversity. While the effects of such changes have been extensively studied in the terrestrial environment, studies focusing on the marine realm are still scarce. Here we used sequence data from one mitochondrial and five nuclear loci to assess the potential influence of Pleistocene climatic changes on the phylogeography and demographic history of a cosmopolitan marine predator, the common dolphin (genus Delphinus). Population samples representing the three major morphotypes of Delphinus were obtained from 10 oceanic regions. Our results suggest that short-beaked common dolphins are likely to have originated in the eastern Indo-Pacific Ocean during the Pleistocene and expanded into the Atlantic Ocean through the Indian Ocean. On the other hand, long-beaked common dolphins appear to have evolved more recently and independently in several oceans. Our results also suggest that short-beaked common dolphins had recurrent demographic expansions concomitant with changes in sea surface temperature during the Pleistocene and its associated increases in resource availability, which differed between the North Atlantic and Pacific Ocean basins. By proposing how past environmental changes had an effect on the demography and speciation of a widely distributed marine mammal, we highlight the impacts that climate change may have on the distribution and abundance of marine predators and its ecological consequences for marine ecosystems. 2013-01-31T04:50:50.994Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23822 Xanthomonas oryzae pv. oryzicola is an important bacterial pathogen responsible for outbreaks of bacterial leaf streak (BLS) on rice, mostly occurring in Asia and parts of Africa. To better monitor epidemics and assess population structures, efficient tools that allow the precise identification and diagnosis of pathogenic populations are needed. In this study, we explored variable numbers of tandem repeats (VNTR) as a fast, reliable, and cost-effective molecular typing tool. Screening of three X. oryzae pv. oryzicola genome sequences (Philippine strain BLS256, Chinese strain GX01, and Malian strain MAI10) predicted 28 candidate VNTR loci. Primer pairs for polymerase chain reaction (PCR) amplification of all 28 loci were designed and applied to a panel of 20 X. oryzae pv. oryzicola strains originating from Asia and Africa. Sequencing of PCR amplicons revealed 25 robust and polymorphic VNTR loci that are shared among Asian and African X. oryzae pv. oryzicola strains. A dendrogram constructed from 25 VNTR loci indicated that most Asian strains are clearly discriminated from African strains. However, in agreement with previous reports, one strain from Mali is related to Asian strains, pointing to a possible introduction of Asian strains to the African continent. The new VNTR-based tool described here is useful for studies of population structures and epidemiological monitoring of X. oryzae pv. oryzicola. 2013-01-24T03:21:47.426Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23837 We studied spatial clustering and activity patterns in the common Barking Gecko (Ptenopus garrulus garrulus) over the course of a breeding season in southern Africa. Only some populations exhibited significant clustering (two of six plots), suggesting that social and spatial organization varies according to factors such as population density and habitat. Clustering at our largest site was not influenced by soil temperature or prey availability, although burrow placement was significantly associated with vegetation coverage. We also examined the timing of the reproductive cycle by testing whether Barking Geckos exhibit protandry (male-first emergence). More males than females were active early in the breeding season and male territories were established before female emergence. Peak activity for 235 Barking Geckos at our primary study site was in late October, although males were significantly more active early in the season, consistent with the protandry model. The Barking Gecko mating system is most consistent with an iteroparous, harem polygynandry with an activity cycle that exhibits protandry. Our study highlights the importance of replicated spatial sampling for studies examining clustering and density effects on reproduction and mating systems. 2013-01-24T03:21:20.442Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:1762 A susceptibility locus for bipolar disorder was previously localized to chromosome 4q35 by genetic linkage analysis. We have applied a positional cloning strategy, combined with association analysis and provide evidence that a cadherin gene, FAT, confers susceptibility to bipolar disorder in four independent cohorts (allelic P-values range from 0.003 to 0.024). In two case–control cohorts, association was identified among bipolar cases with a family history of psychiatric illness, whereas in two cohorts of parent–proband trios, association was identified among bipolar cases who had exhibited psychosis. Pooled analysis of the case–control cohort data further supported association (P = 0.0002, summary odds ratio = 2.31, 95% CI: 1.49–3.59). We localized the bipolar-associated region of the FAT gene to an interval that encodes an intracellular EVH1 domain, a domain that interacts with Ena/VASP proteins, as well as putative β-catenin binding sites. Expression of Fat, Catnb (β-catenin), and the three genes (Enah, Evl and Vasp) encoding the Ena/VASP proteins, were investigated in mice following administration of the mood-stabilizing drugs, lithium and valproate. Fat was shown to be significantly downregulated (P = 0.027), and Catnb and Enah were significantly upregulated (P = 0.0003 and 0.005, respectively), in response to therapeutic doses of lithium. Using a protein interaction map, the expression of genes encoding murine homologs of the FAT (ft)-interacting proteins was investigated. Of 14 interacting molecules that showed expression following microarray analysis (including several members of the Wnt signaling pathway), eight showed significantly altered expression in response to therapeutic doses of lithium (binomial P = 0.004). Together, these data provide convergent evidence that FAT and its protein partners may be components of a molecular pathway involved in susceptibility to bipolar disorder. 2013-01-22T02:10:19.230Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23818 Background: Climate change will lead to intense selection on many organisms, particularly during susceptible early life stages. To date, most studies on the likely biotic effects of climate change have focused on the mean responses of pooled groups of animals. Consequently, the extent to which inter-individual variation mediates different selection responses has not been tested. Investigating this variation is important, since some individuals may be preadapted to future climate scenarios. Methodology/Principal Findings: We examined the effect of CO2-induced pH changes ("ocean acidification") in sperm swimming behaviour on the fertilization success of the Australasian sea urchin Heliocidaris erythrogramma, focusing on the responses of separate individuals and pairs. Acidification significantly decreased the proportion of motile sperm but had no effect on sperm swimming speed. Subsequent fertilization experiments showed strong inter-individual variation in responses to ocean acidification, ranging from a 44% decrease to a 14% increase in fertilization success. This was partly explained by the significant relationship between decreases in percent sperm motility and fertilization success at ΔpH = 0.3, but not at ΔpH = 0.5. Conclusions and Significance: The effects of ocean acidification on reproductive success varied markedly between individuals. Our results suggest that some individuals will exhibit enhanced fertilization success in acidified oceans, supporting the concept of 'winners' and 'losers' of climate change at an individual level. If these differences are heritable it is likely that ocean acidification will lead to selection against susceptible phenotypes as well as to rapid fixation of alleles that allow reproduction under more acidic conditions. This selection may ameliorate the biotic effects of climate change if taxa have sufficient extant genetic variation upon which selection can act. 2013-01-21T04:00:11.767Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23782 Plant height determines a species' position in the canopy and regulates access to light. Shifts in trait values for assemblages (plots) arrayed along abiotic gradients can reflect changes in species composition, and shifts in species trait values. Multivariate analysis was used to quantify the relationship of assemblage-level floristic composition to environmental gradients. Species trait values for maximum height, leaf area, seed size and wood density were quantified for woody species in the assemblage samples, and partitioned into within- and among-assemblage components to enable trait correlations to be identified, including in relation to abiotic gradients. Assemblages in upslope topographic positions had lower height, smaller leaves and higher wood density. Across the assemblages, shifts in species composition, decreasing canopy height and the position of smaller trees in the canopy were all linked to decreasing soil depth in upslope topographic positions. Regardless of stand height, the canopy position of most main canopy dominants remained largely unchanged in response to shifts in environmental gradients. In contrast, shorter-stature tree species retained height along the gradient and subsequently shifted from the subcanopy to the canopy as soil depth and site (plot) canopy height decreased. Within a community, height and position in the canopy can shift under differing environmental conditions. 2013-01-17T07:30:58.115Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23796 Phytoplankton identification and abundance data are now commonly feeding plankton distribution databases worldwide. This study is a first attempt to compile the largest possible body of data available from different databases as well as from individual published or unpublished datasets regarding diatom distribution in the world ocean. The data obtained originate from time series studies as well as spatial studies. This effort is supported by the Marine Ecosystem Model Inter-Comparison Project (MAREMIP), which aims at building consistent datasets for the main Plankton Functional Types (PFT) in order to help validate biogeochemical ocean models by using carbon (C) biomass derived from abundance data. In this study we collected over 293 000 individual geo-referenced data points with diatom abundances from bottle and net sampling. Sampling site distribution was not homogeneous, with 58% of data in the Atlantic, 20% in the Arctic, 12% in the Pacific, 8% in the Indian and 1% in the Southern Ocean. A total of 136 different genera and 607 different species were identified after spell checking and name correction. Only a small fraction of these data were also documented for biovolumes and an even smaller fraction was converted to C biomass. As it is virtually impossible to reconstruct everyone's method for biovolume calculation, which is usually not indicated in the datasets, we decided to undertake the effort to document, for every distinct species, the minimum and maximum cell dimensions, and to convert all the available abundance data into biovolumes and C biomass using a single standardized method. Statistical correction of the database was also adopted to exclude potential outliers and suspicious data points. The final database contains 90 648 data points with converted C biomass. Diatom C biomass calculated from cell sizes spans over eight orders of magnitude. The mean diatom biomass for individual locations, dates and depths is 141.19 μg C l⁻¹, while the median value is 11.16 μg C l⁻¹. Regarding biomass distribution, 19% of data are in the range 0–1 μg C l−1, 29% in the range 1–10 μg C l⁻¹, 31% in the range 10–100 μg C l⁻¹, 18% in the range 100–1000 μg C l⁻¹, and only 3% >1000 μg C l⁻¹. Interestingly, less than 50 species contributed to >90% of global biomass, among which centric species were dominant. Thus, placing significant efforts on cell size measurements, process studies and C quota calculations on these species should considerably improve biomass estimates in the upcoming years. A first-order estimate of the diatom biomass for the global ocean ranges from 449 to 558 Tg C, which converts to 5 to 6 Tmol Si and to an average Si biomass turnover rate of 0.11 to 0.20 d⁻¹. Link to the dataset: preliminary link http://doi.pangaea.de/10.1594/PANGAEA.777384. 2013-01-17T07:30:22.711Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23733 Females of many tephritid fruit flies can mate more than once, and can store ejaculates from multiple males. As well as being an important element of reproductive biology, multiple mating by females is of particular relevance for sterile insect technique programs used to control major tephritid pests. Here we investigate the consequences of multiple mating on fertility of Queensland fruit fly (Bactrocera tryoni) females sequentially mated to irradiated ('sterile') and unirradiated ('normal') males. Females mated by two normal males showed persistent high fertility whereas females mated by two sterile males showed persistent low fertility. Despite lack of association between copula duration and sperm number, fertility of females mated to a normal and then a sterile male increased with duration of the first copulation and decreased with duration of the second. Fertility of females mated to a sterile male and then a normal male was not influenced by duration of the first copulation but increased with duration of the second. These findings reveal a need for increased attention to how factors other than sperm number influence post-copulatory sexual selection in tephritid flies, and in particular how copula duration is linked to sperm storage and usage. 2013-01-14T18:03:30.658Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23735 Artificial structures, such as seawalls, are increasingly disrupting the transition zones between terrestrial and marine systems. They can impede the transport of resources across habitat boundaries and impact adjacent sedimentary ecosystems by modifying hydrodynamics which, in turn, influence sedimentology and erosion. We assessed how structural elements of Avicennia marina mangrove forests along the Parramatta River estuary, Sydney, Australia, differ in the presence or absence of a seawall on the landward side of the forest. These forests are of importance to resident and transient fauna. Sampling of paired mangrove forests, with and without seawalls, supported our hypotheses of structural differences between them. Mangrove forests with seawalls were in some instances less than a third of the width of unconstrained mangrove forests, and had up to twice the pneumatophore density. They often contained less leaf litter and had fewer saplings than forests without seawalls. These results suggest that as shoreline armouring continues, urban mangrove forests and their important ecosystem functions may be negatively impacted. Studies are now needed to ascertain the mechanisms by which seawalls modify these systems. 2013-01-14T18:03:28.032Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23738 Haploid genomes greater than 25,000 Mb are rare, within the animals only the lungfish and some of the salamanders and crustaceans are known to have genomes this large. There is very little data on the structure of genomes this size. It is known, however, that for animal genomes up to 3,000 Mb, there is in general a good correlation between genome size and the percent of the genome composed of repetitive sequence and that this repetitive component is highly dynamic. In this study, we sampled the Australian lungfish genome using three mini-genomic libraries and found that with very little sequence, the results converged on an estimate of 40 of the genome being composed of recognizable transposable elements (TEs), chiefly from the CR1 and L2 long interspersed nuclear element clades. We further characterized the CR1 and L2 elements in the lungfish genome and show that although most CR1 elements probably represent recent amplifications, the L2 elements are more diverse and are more likely the result of a series of amplifications. We suggest that our sampling method has probably underestimated the recognizable TE content. However, on the basis of the most likely sources of error, we suggest that this very large genome is not largely composed of recently amplified, undetected TEs but may instead include a large component of older degenerate TEs. Based on these estimates, and on Thomson's (Thomson K. 1972. An attempt to reconstruct evolutionary changes in the cellular DNA content of lungfish. J Exp Zool. 180:363-372) inference that in the lineage leading to the extant Australian lungfish, there was massive increase in genome size between 350 and 200 mya, after which the size of the genome changed little, we speculate that the very large Australian lungfish genome may be the result of a massive amplification of TEs followed by a long period with a very low rate of sequence removal and some ongoing TE activity. 2013-01-14T18:03:25.151Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23742 We have implemented a process-based isoprene emission model in the HadGEM2 Earth-system model with coupled atmospheric chemistry in order to examine the feedback between isoprene emission and climate. Isoprene emissions and their impact on atmospheric chemistry and climate are estimated for preindustrial (1860-1869), present-day (2000-2009), and future (2100-2109) climate conditions. The estimate of 460 TgC/yr for present-day global total isoprene emission is consistent with previous estimates. Preindustrial isoprene emissions are estimated to be 26% higher than present-day. Future isoprene emissions using the RCP8.5 scenario are similar to present-day because increased emissions resulting from climate warming are countered by CO 2 inhibition of isoprene emissions. The impact of biogenic isoprene emissions on the global O 3 burden and CH 4 lifetime is small but locally significant, and the impact of changes in isoprene emissions on atmospheric chemistry depends strongly on the state of climate and chemistry. 2013-01-14T18:03:13.734Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23744 Understanding the degree of genetic exchange between subspecies and populations is vital for the appropriate management of endangered species. Blue whales (Balaenoptera musculus) have two recognized Southern Hemisphere subspecies that show differences in geographic distribution, morphology, vocalizations and genetics. During the austral summer feeding season, the Antarctic blue whale (B. m. intermedia) is found in polar waters and the pygmy blue whale (B. m. brevicauda) in temperate waters. Here, we genetically analyzed samples collected during the feeding season to report on several cases of hybridization between the two recognized blue whale Southern Hemisphere subspecies in a previously unconfirmed sympatric area off Antarctica. This means the pygmy blue whales using waters off Antarctica may migrate and then breed during the austral winter with the Antarctic subspecies. Alternatively, the subspecies may interbreed off Antarctica outside the expected austral winter breeding season. The genetically estimated recent migration rates from the pygmy to Antarctic subspecies were greater than estimates of evolutionary migration rates and previous estimates based on morphology of whaling catches. This discrepancy may be due to differences in the methods or an increase in the proportion of pygmy blue whales off Antarctica within the last four decades. Potential causes for the latter are whaling, anthropogenic climate change or a combination of these and may have led to hybridization between the subspecies. Our findings challenge the current knowledge about the breeding behaviour of the world's largest animal and provide key information that can be incorporated into management and conservation practices for this endangered species. 2013-01-14T18:02:57.801Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23748 Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli in the water transport system, which reduces the ability of plants to supply water to leaves for photosynthetic gas exchange and can ultimately result in desiccation and mortality. At present we lack a clear picture of how thresholds to hydraulic failure vary across a broad range of species and environments, despite many individual experiments. Here we draw together published and unpublished data on the vulnerability of the transport system to drought-induced embolism for a large number of woody species, with a view to examining the likely consequences of climate change for forest biomes. We show that 70% of 226 forest species from 81 sites worldwide operate with narrow (<1a megapascal) hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe. Safety margins are largely independent of mean annual precipitation, showing that there is global convergence in the vulnerability of forests to drought, with all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment. These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk. 2013-01-14T18:02:40.520Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23752 Cryptosporidium is an important enteric parasite that is transmitted via the fecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Most species of Cryptosporidium are morphologically indistinguishable and can only be identified using molecular tools. Over 24 species have been identified and of these, 7 Cryptosporidium species/genotypes are responsible for most human cryptosporidiosis cases. In Australia, relatively few genotyping studies have been conducted. Six Cryptosporidium species (C. hominis, C. parvum, C. meleagridis, C. fayeri, C. andersoni and C. bovis) have been identified in humans in Australia. However, little is known about the contribution of animal hosts to human pathogenic strains of Cryptosporidium in drinking water catchments. In this review, we focus on the available genotyping data for native, feral and domestic animals inhabiting drinking water catchments in Australia to provide an improved understanding of the public health implications and to identify key research gaps. 2013-01-14T18:02:21.205Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23753 Carrichtera annua (L.) DC. (Brassicaceae) is a widespread weed of the southern rangelands of Australia and there is currently no effective control strategy for this weed outside agricultural systems. Field and glasshouse experiments were used to target various stages of the life cycle of C. annua that, from initial field observations and a review of the literature, appeared to be important or were poorly understood in Australia. Seed production was found to be prodigious with up to 30000 seed m-2 recorded in the field and extensive collection of dry-dispersed seed by ants was documented, similar to that in the native range of C. annua. Two seedbanks, an aerial pod seedbank and a soil seedbank, are key features contributing to the success of this invasive species as the seedbanks are subject to, and protected from, contrasting pressures. The aerial seedbank, usually the larger of the two, protects seed from collection by ants but is susceptible to vertebrate grazing and fire, while the soil seedbank is depleted by ants and seed decay although the adhesive nature of wetted seeds helps stabilise this seedbank. The population can be replenished by either seedbank in one generation, hence both seedbanks need to be targeted to allow successful control. Inhibition of germination by high temperatures in unfavourable conditions and the potential to reach maturation and fruit production very quickly also contribute to the high seed production of this species. 2013-01-14T18:02:17.224Z ]]>