Consistent male–male paternity differences across female genotypes

In a recent paper, we demonstrated that male-female genetic relatedness determines male probability of paternity in experimental sperm competition in the Peron's tree frog (Litoria peronii), with a more closely related male out-competing his rival. Here, we test the hypothesis that a male-male difference in siring success with one female significantly predicts the corresponding difference in siring success with another female. With male sperm concentration held constant, and the proportion of viable sperm controlled statistically, the male-male difference in siring success with one female strongly predicted the corresponding difference in siring success with another female, and alone explained more than 62 per cent of the variance in male-male siring differences. This study demonstrates that male siring success is primarily dictated by among-male differences in innate siring success with less influence of male-female relatedness.

Consistent paternity skew through ontogeny in Peron's tree frog (Litoria peronii)

Background
A large number of studies in postcopulatory sexual selection use paternity success as a proxy for fertilization success. However, selective mortality during embryonic development can lead to skews in paternity in situations of polyandry and sperm competition. Thus, when assessment of paternity fails to incorporate mortality skews during early ontogeny, this may interfere with correct interpretation of results and subsequent evolutionary inference. In a previous series of in vitro sperm competition experiments with amphibians (Litoria peronii), we showed skewed paternity patterns towards males more genetically similar to the female.

Methodology/Principal Findings
Here we use in vitro fertilizations and sperm competition trials to test if this pattern of paternity of fully developed tadpoles reflects patterns of paternity at fertilization and if paternity skews changes during embryonic development. We show that there is no selective mortality through ontogeny and that patterns of paternity of hatched tadpoles reflects success of competing males in sperm competition at fertilization.

Conclusions/Significance
While this study shows that previous inferences of fertilization success from paternity data are valid for this species, rigorous testing of these assumptions is required to ensure that differential embryonic mortality does not confound estimations of true fertilization success.

Climate change, multiple paternity and offspring survival in lizards

Recent work suggests that rising spring temperatures over recent decades have eliminated many lizard populations, and threaten many more worldwide. However, because ambient temperatures constrain activity times in ectotherms, warming conditions (as expected under global climate change scenarios) can increase the duration of seasonal opportunities for courtship and mating. Thus, in species where polyandry results in enhanced offspring viability, a warming climate may not necessarily impair long-term survival. Our nine-year study of a sand lizard (Lacerta agilis) population near the northern range limit in Sweden revealed consistently higher incidence of multiple paternity of clutches in warmer years, and higher viability of offspring from multiply-sired clutches (presumably reflecting the advantages of more intense sperm competition). Any trend to warmer spring temperatures likely will benefit offspring viability in this system, by increasing a female's opportunities to mate with additional males.

Extra-pair paternity in the long-tailed finch Poephila acuticauda

Although the majority of passerine birds are socially monogamous, true genetic monogamy is rare, with extra-pair paternity (EPP) occurring in almost 90% of surveyed socially monogamous species. We present the first molecular data on the genetic breeding system of the long-tailed finch, Poephila acuticauda, a grass finch endemic to the tropical northern savannah of Australia. Although the species forms socially monogamous pair bonds during the breeding season, we found that extra-pair males sired 12.8% of 391 offspring, in 25.7% of 101 broods. Our findings provide only the second estimate of extra-pair paternity in the estrildid finch family.

The colour of paternity: extra-pair paternity in the wild Gouldian finch does not appear to be driven by genetic incompatibility between morphs

In socially monogamous species, individuals can use extra-pair paternity and offspring sex allocation as adaptive strategies to ameliorate costs of genetic incompatibility with their partner. Previous studies on domesticated Gouldian finches (Erythrura gouldiae) demonstrated a genetic incompatibility between head colour morphs, the effects of which are more severe in female offspring. Domesticated females use differential sex allocation, and extra-pair paternity with males of compatible head colour, to reduce fitness costs associated with incompatibility in mixed-morph pairings. However, laboratory studies are an oversimplification of the complex ecological factors experienced in the wild, and may only reflect the biology of a domesticated species. This study aimed to examine the patterns of parentage and sex-ratio bias with respect to colour pairing combinations in a wild population of the Gouldian finch. We utilized a novel PCR assay that allowed us to genotype the morph of offspring before the morph phenotype develops, and to explore bias in morph paternity and selection at the nest. Contrary to previous findings in the laboratory, we found no effect of pairing combinations on patterns of extra-pair paternity, offspring sex ratio, or selection on morphs in nestlings. In the wild, the effect of morph incompatibility is likely much smaller, or absent, than was observed in the domesticated birds. Furthermore, the previously studied domesticated population is genetically differentiated from the wild population, consistent with the effects of domestication. It is possible that the domestication process fostered the emergence (or enhancement) of incompatibility between colour morphs previously demonstrated in the laboratory.

Song and female choice for extrapair copulations in the sedge warbler, Acrocephalus schoenobaenus

Although 90% of passerine birds live in socially monogamous pair bonds, molecular studies have revealed that genetic polygamy occurs in 86% of surveyed passerines, because individuals engage in copulations outside the pair bond (extrapair copulations; EPCs). Most explanations for the occurrence of EPCs involve female gaining indirect benefits from the extrapair male. The sedge warbler is a socially monogamous species in which some offspring result from EPCs (8% in this study). Complex song is a sexually selected male trait used by females which select mates based on a variety of male qualities. We used microsatellite DNA profiling to detect extrapair young and assign paternity. ‘Good genes’ theory predicts that females should engage in EPCs with males of higher quality than their social mate, with resulting fitness benefits. Extrapair males had smaller song repertoires and smaller territories than the social mate. This apparent preference for small-repertoire males as extrapair mates conflicts with the predictions from previous studies of this species. Sudden cessation of song after pairing may mean that song cues are unavailable for later extrapair matings and females may switch to other cues. Such behaviour may lead to different patterns of female choice during social and extrapair mating in the sedge warbler. We conclude that multiple reasons underlie patterns of female choice in this species.

Polymorphic microsatellite loci in the Australian tree frog, Litoria peronii

Eleven novel polymorphic microsatellite loci developed from a microsatellite enriched genomic library, are presented for the Australian tree frog <i>Litoria peroniii>. We screened 29 individuals from a single population and detected high levels of polymorphism for all 11 loci with the number of alleles/locus ranging from 9 to 24. Values of expected and observed heterozygosities ranged from 0.789–0.955 and 0.207–1.00, respectively. These microsatellite markers should prove useful in determining levels of genetic diversity, measuring gene flow and migration, assigning individuals to their most likely population of origin, and in the assignment of paternity.

Within-population variation in ejaculate characteristics in a prolonged breeder, Peron's tree frog, Litoria peronii

Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success (number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after 2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days. Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog and may therefore play an important role in determining siring success both in the presence and absence of sperm competition. We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians.

Improving the effectiveness of the Sex Discrimination Act: recommendations from the 2008 Senate Inquiry

One way to characterise the Rudd Government’s first year in office would be by the flurry of inquiries and reports that it commissioned. Three related to gender equality. The Productivity Commission conducted an inquiry into a national paid maternity, paternity and parental leave scheme and the House of Representatives Standing Committee on Employment and Workplace Relations conducted an inquiry into pay equity. This article is concerned with a third inquiry — the Senate Standing Committee on Legal and Constitutional Affairs (the committee) inquiry into the effectiveness of the Sex Discrimination Act 1984 (Cth) (SDA) in eliminating discrimination and promoting gender equality. These inquiries were not the Rudd Government’s only activities in relation to sex discrimination and gender equality. It also enacted legislation which removed discrimination against same sex couples from 68 Commonwealth laws and announced its intention to accede to the Optional Protocol to the International Convention on the Elimination of All Forms of Discrimination against Women.

Multiple mating and a low incidence of cuckoldry for nest-holding males in the two-spotted goby, Gobiusculus flavescens

Background: A major question in behavioural ecology concerns the relationship between genetic mating systems and the strength of sexual selection. In this study, we investigated the genetic mating system of the two-spotted goby (Gobiusculus flavescens), a useful fish model for the study of sexual selection whose genetic mating system remains uncharacterized. We developed four polymorphic microsatellite markers and used them to conduct parentage analyses on 21 nests collected during the breeding season to examine the rates of multiple mating by males and to test for evidence of alternative mating strategies.

Results: Results of this study indicate that male G. flavescens mate with multiple females and enjoy confidence of paternity. We detected only one instance of sneaking, so cuckoldry contributed a very small percentage (~0.1%) of the total fertilizations in this population. Nests were nearly full and males that maintain larger nests have higher mating and reproductive success, irrespective of body size.

Conclusion: Overall, our investigation shows that G. flavescens is similar to other, related gobies in that the nests of care-giving males often contain eggs from multiple females. However, G. flavescens differs from other gobies in displaying an extremely low rate of cuckoldry. The study of ecological factors responsible for this important

Isolation and characterization of 12 polymorphic tetranucleotide microsatellite loci in the apostlebird (Struthidea cinerea)

The apostlebird (Struthidea cinerea) is an Australian endemic passerine belonging to the Corcoracidae family. The species is highly gregarious throughout the year and the name of the species refers to the apparent prevalence of social groups of around 12 birds. The species is becoming a model system for the study of sociality in vertebrates, which will require the analysis of relatedness, paternity and maternity. We characterize 12 microsatellite loci tested for polymorphism on 25 individuals from a population in western New South Wales, Australia. The number of alleles ranged from 4 to 9 per locus. Expected heterozygosities ranged from 0.69 to 0.88. This microsatellite panel will facilitate future studies that will advance our understanding of dispersal processes, inbreeding avoidance and reproductive skew in social animals.

Polyandry in a marine turtle : females make the best of a bad job

The female perspective on reproductive strategies remains one of the most active areas of debate in biology. Even though a single mating is often sufficient to satisfy the fertilization needs of most females and the act of further mating incurs costs, multiple paternity within broods or clutches is a common observation in nature. Direct or indirect advantage to females is the most popular explanation. However, the ubiquity of this explanation is being challenged by an increasing number of cases for which benefits are not evident. For the first time, we test possible fitness correlates of multiple paternity in a marine turtle, an organism that has long attracted attention in this area of research. Contrary to the wide-spread assumption that multiple mating by female marine turtles confers fitness benefits, none were apparent. In this study, the environment played a far stronger role in determining the success of clutches than whether paternity had been single or multiple. A more likely explanation for observations of multiply sired clutches in marine turtles is that these are successful outcomes of male coercion, where females have conceded to superfluous matings as a compromise. Thus, multiple matings by female marine turtles may be a form of damage control as females attempt to make the best of a bad job in response to male harassment.