Male attractiveness regulates daughter fecundity non-genetically via maternal investment.

Mothers can non-genetically influence offspring phenotype in response to environmental conditions, including mate attractiveness. If such 'maternal effects' influence the offspring's reproduction and F2 generation, there is a mechanism for non-genetic trans-generational effects on phenotype, including epigenetic phenomena, with implications for evolution and population dynamics. We demonstrate in the zebra finch Taeniopygia guttata such non-genetic effects on offspring fecundity and the size of early stage F2 (eggs) in response to experimentally manipulated father's attractiveness. Our experimental design allowed us to deduce that the mechanism for this non-genetic paternal effect was via maternal investment in eggs. This affected female offspring size and, consequently, fecundity and F2 (egg) size. This demonstrates that female perception of mate attractiveness can have non-genetic, trans-generational fitness consequences and this may have important implications for the evolution of sexually selected traits and population dynamics.

Finding fathers: spatio-temporal analysis of paternity assignment in grey seals (Halichoerus grypus).

Molecular studies of pinniped breeding systems exhibit a broad range of agreement and disagreement with observational indices of male breeding success. Grey seal studies have reported considerable discrepancies between genetic and behavioural paternity measures that have been interpreted as evidence of previously unidentified male strategies and/or tactics. Therefore, these studies have the power to fundamentally alter our perceptions of mating systems. However, other pinniped studies exhibit no such disagreements, and one possible explanation for disparities may be sampling biases in space and time. Therefore, it is essential that potential sampling biases are examined to evaluate the likelihood of previously unidentified male strategies. We examined paternities assigned at the North Rona grey seal colony between 1999 and 2002 in relation to concurrent detailed behavioural and locational data for males and females. We found that (i) for females observed in sexual interaction(s) during their oestrus period, it was highly probable that one of the interacting males fathered their next pup; (ii) over 80% of assigned paternities agreed with observations of the in-colony behaviour and spatio-temporal proximity of the males and females involved; and (iii) a minority of females exhibit mate choice and seek sires outside their local male's home range, although evidence suggests that these females mate on the colony rather than at sea. In conclusion, nearly all paternities assigned agreed with expectation based upon detailed knowledge of the spatio-temporal patterns of individuals during the breeding season. We found little evidence of unidentified male strategies at North Rona, Scotland, whereas further examination of mechanisms of female choice may be productive.

Sex-biased investment in yolk androgens depends on female quality and laying order in zebra finches (Taeniopygia guttata).

The Trivers-Willard hypothesis predicts sex biases in parental investment according to parental condition. In addition, parents may need to sex bias their investment if there is an asymmetry between the sexes in offspring fitness under different conditions. For studying maternal differential investment, egg resources are ideal subjects because they are self contained and allocated unequivocally by the female. Recent studies show that yolk androgens can be beneficial to offspring, so here we test for sex-biased investment with maternal investment of yolk testosterone (T) in zebra finch (Taeniopygia guttata) eggs. From the Trivers-Willard hypothesis, we predicted females to invest more in male eggs in optimum circumstances (e.g. good-condition mother, early-laid egg), and more in female eggs under suboptimal conditions (e.g. poor-condition mother, late-laid egg). This latter prediction is also because in this species there is a female nestling disadvantage in poor conditions and we expected mothers to help compensate for this in female eggs. Indeed, we found more yolk T in female than male eggs. Moreover, in accordance with our predictions, yolk T in male eggs increased with maternal quality relative to female eggs, and decreased with laying order relative to female eggs. This supports our predictions for the different needs and value of male and female offspring in zebra finches. Our results support the idea that females may use yolk androgens as a tool to adaptively manipulate the inequalities between different nestlings.

Molecular phylogeny of the livebearing Goodeidae (Cyprinodontiformes).

The Goodeinae is a speciose group of viviparous freshwater fishes endemic to the Mesa Central of Mexico. The current taxonomy of the group is based on morphology associated with viviparity and several of the groupings are questionable. We sequenced part of the mitochondrial cytochrome c oxidase subunit I (COI) gene (627bp) and control region (approximately 430bp aligned) of representatives of 36 species (all genera) of goodeid fishes in order to establish phylogenetic relationships among the taxa. Findings support the monophyly of the Goodeidae, the sister-group relationship of the Empetrichthyinae and Goodeinae, and the relationship of Profundulus to the Goodeidae. All goodeine genera but Xenotoca were recovered as monophyletic. Many of the higher-level relationships within the group contradict the findings of previous studies based upon morphology. The rate of molecular change in COI (0.9% per Myr), calibrated with the fossil record and geological data, suggests an approximate age for the Goodeidae of 16.5Myr. The majority of divergence within the Goodeinae appears to have occurred during the Miocene, with subsequent cladogenesis in the Pliocene and Pleistocene. Most recent speciation appears allopatric. River piracy, particularly involving the Rio Ameca basin, has played a significant role in the diversification of the Goodeinae.