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:11123 The captive zebra finch, Taeniopygia guttata, has become one of the key vertebrate model systems for studying a range of behavioural, physiological and neurological phenomena. In particular, this species has played a key role in developing our understanding of sexual selection and sperm competition. In contrast with the large number of studies using domesticated zebra finches, relatively few studies have focused on free-living populations of wild zebra finches. Investigating the incidence of extrapair paternity in zebra finches in the Australian desert, we found a very low level; 1.7% of 316 offspring from four of 80 broods fathered outside the pair bond. These numbers contrast with the high levels of extrapair paternity observed in domesticated aviary populations, and suggest a low level of sperm competition and sexual selection in natural populations. Our finding of such a low rate of extrapair paternity in the wild zebra finch suggests that it is one of the most genetically monogamous of all passerine species and that has important implications for future studies of this model organism in studies of sexual selection and reproductive biology. In addition, we found that 5.4% of 316 offspring were not related to either putative parent and hatched from eggs that had been dumped by intraspecific brood parasites. 2011-01-06T18:10:50.862Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:11125 Extra-pair paternity (EPP) is an important component of avian mating systems and can affect avian biodiversity by contributing to isolation between related forms. Over the past three decades, molecular surveys of more than 100 species have revealed EPP to be widespread in socially monogamous birds, significantly increasing the variance in reproductive success among males and helping to drive sexual selection on traits with which it is often associated (e.g. song, ornamental plumage). In the past 7 years many studies have also demonstrated that the distribution of EPP within a population is related to the level of genetic similarity between the parents. Multiple mating combined with sperm competition that follows a genetically loaded raffle model, would provide a route through which females could target compatible genes and act as an effective post-copulatory isolating mechanism between closely related species or forms in sympatry. EPP can result in significant divergence between an observed social mating system and the true underlying genetic mating system of a population or species, and needs to be considered in our attempts to define and understand species or morphs as genetically isolated populations in many cases. 2011-01-06T18:10:34.995Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:11128 Birds are a particularly good group with which to examine the importance of maternal effects, as parental contributions can be relatively easily quantified compared with other groups. There have undoubtedly been more studies on maternal effects in the Zebra Finch than any other single bird species. Studies of this species have examined the importance of maternal effects mediated through sex allocation, size, nutrients and hormones of of eggs, incubation behaviour and provisioning levels. A synthesis of all of this work illustrates some contrasting results (e.g. many high-profile results have failed to be replicated), some very common patterns (e.g. investment shifts through the laying sequence), and potentially interesting and complex interactions between traits (e.g. between sex of offspring and hormonal profiles of eggs). This extensive collection of work on the Zebra Finch provides useful general insight into the patterns of maternal investment in birds and the effects on offspring phenotype. However, we caution that the literature is probably littered with studies that have overemphasised the importance of some maternal effects and recent studies have highlighted analytical and logical flaws that have probably led to misplaced confidence in some of the findings reported to date. Finally, it is worth considering that the bulk of the literature is based on studies of captive domesticated birds and ecological and physiological data from individuals in the wild is currently lacking. The biological relevance of maternal effects documented in this model species is therefore unclear. 2011-01-06T18:10:26.750Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:11130 Individuals in socially monogamous species may participate in copulations outside of the pair bond, resulting in extra-pair offspring. Although males benefit from such extra-pair behavior if they produce more offspring, the adaptive function of infidelity to females remains elusive. Here we show that female participation in extra-pair copulations, combined with a genetically loaded process of sperm competition, enables female finches to target genes that are optimally compatible with their own to ensure fertility and optimize offspring viability. Such female behavior, along with the postcopulatory processes demonstrated here, may provide an adaptive function of female infidelity in socially monogamous animals. 2011-01-06T18:10:14.058Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:10644 The addition of red and green color bands is a commonly used method for manipulating male attractiveness in the zebra finch (Taeniopygia guttata), providing insight into the study of maternal investment and sexual selection. The addition of artificial ornaments has been assumed to manipulate a females’ perception of the male, rather than affecting intrinsic qualities of the male himself. Here, however, we reveal that the artificial band color worn by a male changes his body mass, condition, and courtship display rate. Males wearing red color bands in aviaries prior to mate-choice trials had a significantly higher song rate during trials than those wearing green color bands, alongside a significant increase in mass change and condition. Male song rate was found to significantly correlate with female preference alongside a female preference for red-banded males. However, male song rate in turn increased when female response was positive, suggesting a social feedback between the interacting birds. Our data suggest the presence of socially mediated feedback mechanisms whereby the artificial increase in attractiveness or dominance of a male directly affects other aspects of his attractiveness. Therefore, housing birds in social groups while manipulating attractiveness can directly influence other male qualities and should be accounted for by future studies. 2010-11-19T08:50:48.820Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:10645 Theory predicts that parents should adjust reproductive investment in a current breeding attempt by considering the relative fitness benefits of current and future reproductive attempts. Empirical tests, however, have proved problematic because of the difficulties in isolating variables that yield clear and predictable fitness returns to individuals and because partner compensation in socially monogamous species is likely to confound individual investment strategies. We test the effect of parental investment by males and females in the color polymorphic Gouldian finch (Erythrura gouldiae), a species with mutual mate choice and high fitness costs when breeding with incompatible partners. Using a within-individual experimental design, in which both males and females were forced to breed with mates of the same (matched) and different (mixed) color morph, we show that females, but not males, increased their provisioning effort when breeding with compatible mates. By crossfostering offspring within and between matched and mixed pairs, we also found that foster offspring reared by matched pairs, with increased female provisioning, were healthier, grew and developed faster, and fledged earlier than offspring reared by mixed pairs. Furthermore, due to the experimental design, these effects were directly mediated by differential investment by females and not by male compensation. Thus, our results provide support for maternal (but not paternal) effects in response to mate quality. 2010-11-19T08:50:44.917Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:10451 The Australian zebra finch, Taeniopygia guttata, is a widely used model organism, yet few studies have compared domesticated and wild birds with the aim of examining its relevance as an evolutionary model species. Domestic and wild broods hatch over approximately 4 and 2 days, respectively, which is important given that nestlings can fledge after as little as 12 days, although 16-18 days is common. We aimed to evaluate the extent to which the greater hatching asynchrony in domestic stock may effect reproductive success through greater variance in size hierarchies, variance in within-brood growth rates, and partial brood mortality. Therefore, by simultaneously controlling brood sizes and experimentally manipulating hatching intervals in both domesticated and wild birds, we investigated the consequences of hatching intervals for fledging success and nestling growth patterns, as well as trade-offs. Fledging success was similarly high in domestic and wild broods of either hatching pattern. Nonetheless, between-brood analyses revealed that domestic nestlings had significantly higher masses, larger skeletal characters, and longer wings than their wild counterparts, although wild nestlings had comparable wing lengths at the pre-fledging stage. Moreover, within-brood analyses revealed only negligible differences between domestic and wild nestlings, and larger effects of hatching order and hatching pattern. Therefore, despite significant differences in the hatching intervals, and the ultimate size achieved by nestlings, the domestication process does not appear to have significantly altered nestling growth trade-offs. The present study provides reassuring evidence that studies involving domesticated zebra finches, or other domesticated model organisms, may provide reasonable adaptive explanations in behavioural and evolutionary ecology. 2010-11-05T04:30:57.760Z ]]>