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In promiscuous species, fitness estimates obtained from genetic parentage may often reflect both pre- and post-copulatory components of sexual selection. Directly observing copulations can help isolate the role of pre-copulatory selection, but such behavioral data are difficult to obtain in the wild and may also overlook post-copulatory factors that alter the relationship between mating success and reproductive success. To overcome these limitations, we combined genetic parentage analysis with behavioral estimates of size-specific mating in a wild population of brown anole lizards (Anolis sagrei). Males of this species are twice as large as females and multiple mating among females is common, suggesting the scope for both pre- and post-copulatory processes to shape sexual selection on male body size. Our genetic estimates of reproductive success revealed strong positive directional selection for male size, which was also strongly associated with the number of mates inferred from parentage. In contrast, a male's size was not associated with the fecundity of his mates or his competitive fertilization success. By simultaneously tracking copulations in the wild via the transfer of colored powder to females by males from different size quartiles, we independently confirmed that large males were more likely to mate than small males. We conclude that body size is primarily under pre-copulatory sexual selection in brown anoles, and that post-copulatory processes do not substantially alter the strength of this selection. Our study also illustrates the utility of combining both behavioral and genetic methods to estimate mating success to disentangle pre- and post-copulatory processes in promiscuous species. [ABSTRACT FROM AUTHOR]

Pre-copulatory female mate choice based on male ultraviolet (UV) coloration has been demonstrated in several vertebrate species; however, post-copulatory mechanisms have been largely overlooked. Here, we investigated female mate preference based on male UV coloration in the common lizard Zootoca vivipara , in which males display conspicuous UV coloration on their throat. During two successive years, we staged sequential mating trials between females and four different males with UV-reduced or control belly and throat coloration. We recorded pre-copulatory female behaviour, copulation behaviour and assigned paternity to all offspring. Females were more aggressive towards UV-reduced males and, during the second year, UV-reduced males had a lower probability of siring at least one egg (fertilization success) during the last mating trials. However, in the second year, copulation was shorter with control males. Altogether, our results suggest that females exert subtle pre-copulatory mate preference based on male UV ornaments and, conditional on the study year and female mating history, some degree of post-copulatory preference for UV-control males leading to differential male fertilization success. This study suggests that UV-based female mate choice may be more widespread than previously thought in vertebrates, and emphasizes the importance of using a study design well adapted to the species reproductive behaviour. [ABSTRACT FROM AUTHOR]

In polyandrous species, sexual selection extends beyond mating competition to selection for egg fertilization. As a result, the degree to which factors influencing mating success impact overall reproductive success becomes variable. Here, we used a longitudinal behavioural and genetic dataset for a population of eastern water dragons (Intellagama lesueurii) to investigate the degree to which male dominance, a pre-mating selection trait, influences overall reproductive success, measured as the number of surviving offspring. Moreover, we examine the interactive effects with a genetic trait, individual inbreeding, known to influence the reproductive success of males in this species. We found fitness benefits of male dominance, measured as body size and frequency of dominance behaviours displayed. However, individuals’ propensity to display dominance behaviours had mixed effects, depending on the degree of inbreeding. While inbred males benefited from frequent displays, highly outbred males exhibited better reproductive outputs when displaying to a lesser extent. Given that outbred males have enhanced reproductive success in this species, the costs of displaying dominance behaviours may outweigh the benefits. Overall, our results demonstrate the fitness benefits of dominance in a polyandrous lizard, and suggest that these are modulated by an independent genetic trait. Our results may contribute to explaining the presence of alternative mating tactics in this species, owing to the variability in net fitness benefits of dominance. Our findings also reveal the challenges associated with investigating fitness traits in isolation, which may undermine the validity of results when important interactions are ignored. [ABSTRACT FROM AUTHOR]

Why the sexual climax, in humans, results in a pleasurable experience remains an important biological question. Analysis of evolutionary traits in numerous Vertebrates suggests that orgasm evolved through three phylogenetic stages during the transition from external to internal fertilization and viviparity. First, orgasm is directly dependent on ejaculation in males and the expulsion of fluids from the ovarian and urethral glands (Skene's) in females. I propose that sexual orgasm could come from the primitive reflex of discharging gametes to ensure reproduction. Thus, the understanding of orgasm should not be reduced to a penis- or a clitoris-centred paradigm. Secondly, orgasm has evolved to stimulate sexual activity because the evolutionary transition from external fertilization to internal fertilization has been accompanied in numerous species with a lessening in reproductive rates. Because sexual activity encourages reproduction, it can be argued that orgasm has evolved to increase sexual activity, particularly in viviparous species with low reproductive rates. Third, internal fertilization in the genital tract of females weakens the visibility of the putative success of fertilization. Female sexual fluids and proteins can bias fertilization in favour of preferred males. Because orgasm could promote a better choice of partner, I argue that female orgasm may have evolved as a post-copulatory selection tactic by which females can increase their control of mates. [ABSTRACT FROM AUTHOR]

Male fitness is dependent on sexual traits that influence mate acquisition (precopulatory sexual selection) and paternity (post-copulatory sexual selection), and although many studies have documented the form of selection in one or the other of these arenas, fewer have done it for both. Nonetheless, it appears that the dominant form of sexual selection is directional, although theoretically, populations should converge on peaks in the fitness surface, where selection is stabilizing. Many factors, however, can prevent populations from reaching adaptive peaks. Genetic constraints can be important if they prevent the development of highest fitness phenotypes, as can the direction of selection if it reverses across episodes of selection. In this study, we examine the evidence that these processes influence the evolution of the multivariate sex comb morphology of male Drosophila simulans. To do this, we conduct a quantitative genetic study together with a multivariate selection analysis to infer how the genetic architecture and selection interact. We find abundant genetic variance and covariance in elements of the sex comb. However, there was little evidence for directional selection in either arena. Significant nonlinear selection was detected prior to copulation when males were mated to nonvirgin females, and post-copulation during sperm offence (again with males mated to nonvirgins). Thus, contrary to our predictions, the evolution of the D. simulans sex comb is limited neither by genetic constraints nor by antagonistic selection between pre- and post-copulatory arenas, but nonlinear selection on the multivariate phenotype may prevent sex combs from evolving to reach some fitness maximizing optima. [ABSTRACT FROM AUTHOR]

A large body of evidence suggests that major histocompatibility complex (MHC) genotype influences mate choice. However, few studies have investigated MHC-mediated post-copulatory mate choice under natural, or even semi-natural, conditions. We set out to explore this question in a large semi-free-ranging population of mandrills ( Mandrillus sphinx) using MHC-DRB genotypes for 127 parent-offspring triads. First, we showed that offspring MHC heterozygosity correlates positively with parental MHC dissimilarity suggesting that mating among MHC dissimilar mates is efficient in increasing offspring MHC diversity. Second, we compared the haplotypes of the parental dyad with those of the offspring to test whether post-copulatory sexual selection favored offspring with two different MHC haplotypes, more diverse gamete combinations, or greater within-haplotype diversity. Limited statistical power meant that we could only detect medium or large effect sizes. Nevertheless, we found no evidence for selection for heterozygous offspring when parents share a haplotype (large effect size), genetic dissimilarity between parental haplotypes (we could detect an odds ratio of ≥1.86), or within-haplotype diversity (medium-large effect). These findings suggest that comparing parental and offspring haplotypes may be a useful approach to test for post-copulatory selection when matings cannot be observed, as is the case in many study systems. However, it will be extremely difficult to determine conclusively whether post-copulatory selection mechanisms for MHC genotype exist, particularly if the effect sizes are small, due to the difficulty in obtaining a sufficiently large sample. Am. J. Primatol. 75:1021-1031, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The relative force of direct and indirect selection underlying the evolution of polyandry is contentious. When females acquire direct benefits during mating, indirect benefits are often considered negligible. Although direct benefits are likely to play a prominent role in the evolution of polyandry, post-mating selection for indirect benefits may subsequently evolve. We examined whether polyandrous females acquire indirect benefits and quantified direct and indirect effects of multiple mating on female fitness in a nuptial gift-giving spider ( Pisaura mirabilis). In this system, the food item donated by males during mating predicts direct benefits of polyandry. We compared fecundity, fertility and survival of singly mated females to that of females mated three times with the same (monogamy) or different (polyandry) males in a two-factorial design where females were kept under high and low feeding conditions. Greater access to nutrients and sperm had surprisingly little positive effect on fitness, apart from shortening the time until oviposition. In contrast, polyandry increased female reproductive success by increasing the probability of oviposition, and egg hatching success indicating that indirect benefits arise from mating with several different mating partners rather than resources transferred by males. The evolution of polyandry in a male-resource-based mating system may result from exploitation of the female foraging motivation and that indirect genetic benefits are subsequently derived resulting from co-evolutionary post-mating processes to gain a reproductive advantage or to counter costs of mating. Importantly, indirect benefits may represent an additional explanation for the maintenance of polyandry. [ABSTRACT FROM AUTHOR]

Major histocompatibility complex (MHC) genes are classical examples of 'good genes' because of their critical participation in fighting and eradicating pathogens. Here, we investigated the inheritance of alleles across a highly polymorphic MHC class II B gene in a socially monogamous raptor, the lesser kestrel Falco naumanni. Allele segregation patterns from parents to offspring were monitored in 44 breeding pairs and 228 nestlings. We found that a particular array of closely related alleles, defined by the presence of two of the three commonest alleles (only three alleles exhibit frequencies larger than 10 % in the studied populations), showed significant transmission ratio distortions when inherited from males ( k = 0.702 ± 0.188, p < 0.001), but not when inherited from females ( k = 0.563 ± 0.207, p = 0.19). We believe that this result is consistent with the targeting of genetically loaded spermatozoa by female kestrels. Our analyses do not allow discerning, however, whether this pattern is predominantly driven by sperm competition or differential maternal allocation. This trend, nonetheless, would agree with the contrasting relative frequencies of these alleles between western and eastern populations of lesser kestrels and sustains their contemplation as locally adapted alleles, as suggested in previous studies. Ours is one of the very few studies supporting the MHC-based female cryptic choice in birds and opens inspiring lines of research. In particular, future studies addressing the influence of candidate MHC alleles on individual fitness and their effect on maternal adjustments associated with reproduction should be encouraged. [ABSTRACT FROM AUTHOR]