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Many methods of controlling invasive crayfishes have limited success because they fail to target all life stages of the population, notably by capturing only large adults that can result in increased juvenile recruitment by removing intraspecific predation. An alternative approach uses the sterile male release technique that involves the mass release of sterile males into the environment, which then mate with fertile females, resulting in unfertilised eggs and, ultimately, reduced juvenile recruitment. This does, however, rely on the sterilised males exhibiting behaviours similar to non-sterilised (entire) males and remaining attractive to females during mate choice. Post-copulatory male guarding behaviour and female promiscuity might also be affected by male sterilisation. To test for the presence of normal reproductive behaviours in sterilised male American signal crayfish Pacifastacus leniusculus, a two-stage experiment examined how sterilisation affects female mate choice and promiscuity, male hierarchical status (relative dominance) and post-copulation guarding. Sterilised males showed similar reproductive behaviours to entire males and remained as attractive to females, with no differences in relative dominance. Post-copulation, guarding behaviours were also unaffected. Females did not display promiscuous behaviour and this was unaffected by whether males were entire or sterilised. The results demonstrated that sterilised males were equally as capable as entire males of achieving dominance and winning mates. In combination, these findings suggest that male sterilisation could be an effective control technique to help reduce juvenile recruitment in wild P. leniusculus populations by reducing reproductive success.

Cephalopods are a remarkable group for studies on sexual selection, due to their complex reproductive behavior, pronounced sexual dimorphism, polygamous behavior, as well as cumulative evidence of pre- and postcopulatory male-male competition and female choice in the group. is paper provides a review of sexual selection studies on cephalopods, with an emphasis on the loliginid squid mating system. In this system, males may adopt alternative reproductive tactics (ART) and display male intrasexual dimorphism, with each morph generally exhibiting distinct behaviors and ejaculate traits. Consort males typically transfer ejaculates to the female mantle cavity, while sneaker males typically transfer ejaculates to the female buccal region, where a sperm storage organ is located. Each site provides distinct fertilization environments for the ejaculates of each morph, differing in the availability of eggs, gamete protection, and timing between mating and fertilization. Accordingly, the ejaculates of each morph show putative adaptations for each site, differing in size, morphology, sperm release duration, and sperm behavior. Although solid evidence is lacking for most loliginids, cryptic female choice may occur in this system through, for example, spermatangia removal or egg string manipulation during fertilization. In addition, recent evidence for one loliginid species indicates that adoption of male ART is ontogenetic and may represent two alternative pathways: from immature males (i) directly to consort phenotype or (ii) going through a sneaker phase, then switching to consort morph. The second pathway would, therefore, imply striking change in behavior, physiology, and ejaculates. Moreover, data on the age of this species suggests that the adoption of sneaker tactic early in life may be associated with extending the male mating period by 25%. With such a peculiar system, loliginids should prove useful not only for comprehending the evolution of female promiscuity and ART in cephalopods, but also as an emerging nonvertebrate and nonarthropod model for testing sperm competition models.

Female promiscuity is a pervasive selective force on male reproductive traits, and the strength of sexual selection is predicted to influence the tradeoff between lifespan and reproduction. In species where sexual selection is intense, males are predicted to invest in sexual strategies that shorten their lifespan, potentially resulting in female-biased sexual dimorphism in longevity. However, comparative analyses have provided contrasting results, potentially due to the use of broad mating system categories or sexual size dimorphism as a proxy for sexual selection. Here, we used female remating rate (i.e., female promiscuity) as a more direct measure of sexual selection strength, and conducted a phylogenetic comparative analysis of the relationship between female remating rate and sexual dimorphism in lifespan in 29 species of Drosophila. We did not find strong evidence that female remating rate was correlated with sexual-dimorphism in lifespan. However, we found that male and female lifespans are positively correlated among species, and that phylogeny and residual variance (i.e., variation in non-phylogenetic factors) are important in determining female remating rate, male and female lifespans separately, and the correlation between male and female lifespan. We suggest that variation in the nature of sexual competition as well as variation between studies could account for some of the unexplained variation among species in the relation between female remating rate and sexual dimorphism in lifespan.

Mating activity of a wild Mueller’s gibbon group (Hylobates muelleri) was observed in the Danum Valley Conservation Area, Sabah, Malaysia. The purpose of this study was to investigate the function of copulation calls in gibbons. The female emitted copulation calls at the time of intromission and pelvic thrusting. Copulation calls were composed of two notes and one of them was sung only while mating. Approximately half of copulation calls were sung near the range boundary. Mating with copulation calls sometimes occurred while singing. According to the model that female copulation calls have evolved under the selective pressures of risk of infanticide and sperm competition, copulation calls should be rare in species with little female promiscuity. As gibbons usually live in pair-living social organization and have a monogamous mating system, no vocal signals by female gibbons are considered to be needed. However, clear copulation calls were emitted by the female. It suggests that the relationship between paired gibbons is unstable. Copulation calls by the female Mueller’s gibbon may function to increase mate guarding and strengthen the pair bond.

Body and testes size can significantly affect male reproductive success under pre- and post-copulatory sexual selection. Testicular relative mass and/or volume are often used as a characteristic of sperm competitive ability in a comparison of phylogenetically close mammal species. Mus spicilegus males have the largest testes relative to body mass of any Mus species, which is often an indicator of high sperm competition. These findings suggest that these mound-building mice are probably not strictly monogamous. Here, we show the quantitative characteristics of testicular size, variation, and allometry of two sibling species with a different social and mating system, the house mouse (Mus musculus) and the mound-building mouse (M. spicilegus) from the Western Carpathian (Slovakia). We investigated whether testicular size (testicular length/width) was correlated with the head-and-body length and body weight, which are not involved in reproduction. Our results confirmed higher testicular values in M. spicilegus than in M. musculus. Similarly, the high phenotypic variance and positive allometry in testicular growth confirmed the suggestion that males with larger testes and a higher production of testosterone may be more competitive and more successful in post-copulatory selection.

This study investigates promiscuity impacts, pregnancy impacts and abortion impacts of female undergraduates on management of the University of Benin educational theatre program, with implications on general theatre practice including Muson and Nollywood, in Nigeria. There are widespread speculations that female undergraduate theatre students are promiscuous and therefore highly prone to pregnancies and abortions for reasons or factors not confirmed by research. At least no such specific extensive study has been carried out in the University of Benin Theatre on this topic. Yet many female students are branded and treated merely as ‘debased females and prospective prostitutes’, and do not enjoy the goodwill, support, respect and honor their counterparts in the social, basic and environmental sciences as well as other fields of academic studies enjoy. This would be tantamount to a great disservice and injustice that need to be urgently addressed if a rigorous academic inquiry proves otherwise. Not to mention the undiscovered negative impacts the problem may have had, or currently be having on the training and practice of theatre arts in Nigeria: hence this investigation. The methodology, the subjects of study and study sample were carefully and systematically determined. The findings are mostly positive regarding the negative behavior investigated. Hence the recommendations point to measures aimed at checking and restricting these vices as well as their impact to a minimum as well as towards improving the moral, academic and managerial framework of educational theatre programs in Nigeria.

The aim of this study was to explore how people's sexual history affects their attractiveness. Using an Internet survey, 188 participants rated their willingness to engage in a relationship with a hypothetical individual with a specified number of past sexual partners, ranging from 0 to 60+. The effect of past partner number was very large. Average willingness ratings initially rose as past partner number rose, but then fell dramatically. For short-term relationships, men were more willing than women to get involved (although the difference was not large). For long-term relationships, in contrast, there was virtually no sex difference. Thus, contrary to the idea that male promiscuity is tolerated but female promiscuity is not, both sexes expressed equal reluctance to get involved with someone with an overly extensive sexual history. Finally, participants with an unrestricted sociosexual orientation (high SO participants) were more tolerant than low SO participants of prospective mates with higher numbers of past sexual partners but were also less tolerant of prospective mates with low numbers of past sexual partners.

Adaptive explanations for the evolution of extra-pair paternity (EPP) in birds often assume cuckolding males to be better-ornamented than cuckolded males. Several studies have confirmed that either male sexual ornamentation is associated with EPP or that phenotypes of cuckolded and cuckolding males differ. Expression of male ornamentation may change with age; however, a recent meta-analysis has identified age itself as an important factor that differed in cuckolding and cuckolded males. The age of social female partner may also affect EPP, though this has received little attention. Here, by using detailed data on age of individual barn swallows (Hirundo rustica rustica), we identified age as the major predictor of male and female promiscuity. Our results revealed that, whereas a male’s ability to obtain an extra-pair mate increased linearly with age, the only predictor of the probability of a male being cuckolded was the age of his social partner, with older females engaging more frequently in EPP. In contrast, male ornamentation was not significantly related to EPP pattern. Tarsus length was the sole significant phenotypic trait in comparison between cuckolding and cuckolded males. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population was ornament driven. This may indicate either a non-adaptive scenario for EPP, for example with older males better able to coerce females into copulation, or EPP mating based on other than absolute mate-choice criteria associated with the expression of male ornamentation. We analysed patterns of extra-pair paternity (EPP) in barn swallows. Derived from observation of 160 nests, our results appear to differ from the findings of some previous studies that identified ornamental traits as being associated with extra-pair and within-pair paternity (WPP) in this iconic model taxon of sexual selection. In particular, tail streamer length had no detectable association with WPP or a male’s ability to obtain an extra-pair partner. Pairwise comparisons of cuckolded and cuckolding males, involving 76 mixed paternity nests, also supported the hypothesis that male ornamentation does not play a role in determining EPP patterns in the focal barn swallow population. When statistically controlled for clutch initiation date, the probability of obtaining an extra-pair partner only increased with increasing age of males, while WPP was only associated with the age of their female social partners. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population is ornament driven and indicated that age, rather than ornaments, would be a better predictor of paternity.

Background Female promiscuity is highly variable among birds, and particularly among songbirds. Comparative work has identified several patterns of covariation with social, sexual, ecological and life history traits. However, it is unclear whether these patterns reflect causes or consequences of female promiscuity, or if they are byproducts of some unknown evolutionary drivers. Moreover, factors that explain promiscuity at the deep nodes in the phylogenetic tree may be different from those important at the tips, i.e. among closely related species. Here we examine the relationships between female promiscuity and a broad set of predictor variables in a comprehensive data set (N = 202 species) of Passerides songbirds, which is a highly diversified infraorder of the Passeriformes exhibiting significant variation in female promiscuity. Results Female promiscuity was highly variable in all major clades of the Passerides phylogeny and also among closely related species. We found several significant associations with female promiscuity, albeit with fairly small effect sizes (all R2 ≤ 0.08). More promiscuous species had: 1) less male parental care, particularly during the early stages of the nesting cycle (nest building and incubation), 2) more short-term pair bonds, 3) greater degree of sexual dichromatism, primarily because females were drabber, 4) more migratory behaviour, and 5) stronger pre-mating sexual selection. In a multivariate model, however, the effect of sexual selection disappeared, while the other four variables showed additive effects and together explained about 16% of the total variance in female promiscuity. Female promiscuity showed no relationship with body size, life history variation, latitude or cooperative breeding. Conclusions We found that multiple traits were associated with female promiscuity, but these associations were generally weak. Some traits, such as reduced parental care in males and more cryptic plumage in females, might even be responses to, rather than causes of, variation in female promiscuity. Hence, the high variation in female promiscuity among Passerides species remains enigmatic. Female promiscuity seems to be a rapidly evolving trait that often diverges between species with similar ecologies and breeding systems. A future challenge is therefore to understand what drives within-lineage variation in female promiscuity over microevolutionary time scales. Electronic supplementary material The online version of this article (10.1186/s12862-019-1493-1) contains supplementary material, which is available to authorized users.

How males and females contribute to joint reproductive success has been a long-standing question in sexual selection. Under postcopulatory sexual selection (PSS), paternity success is predicted to derive from complex interactions among females engaging in cryptic female choice and males engaging in sperm competition. Such interactions have been identified as potential sources of genetic variation in sexually selected traits but are also expected to inhibit trait diversification. To date, studies of interactions between females and competing males have focused almost exclusively on genotypes and not phenotypic variation in sexually selected traits. Here, we characterize within- and between-sex interactions inDrosophila melanogasterusing isogenic lines with heritable variation in both male and female traits known to influence competitive fertilization. We found surprisingly few genotypic interaction effects on various stages of PSS such as female remating interval, copulation duration, sperm transfer, or sperm storage. Only the timing of female sperm ejection depended on female × male genotypic interactions. By contrast, several reproductive events, including sperm transfer, female sperm ejection and sperm storage, were explained by two- and three-way interactions among sex-specific phenotypes. We also documented complex interactions between the lengths of competing males’ sperm and the female seminal receptacle, which are known to have experienced rapid female-male co-diversification. Our results highlight the non-independence of sperm competition and cryptic female choice and demonstrate that complex interactions between the sexes do not limit the ability of multivariate systems to respond to directional sexual selection.Significance statementFor species with internal fertilization and female promiscuity, postcopulatory sexual selection (PSS) is believed to depend, in part, on complex interactions between rival males and between the sexes. Although little investigated, clarifying such interactions is critical as they may limit the efficacy of PSS in the diversification of reproductive traits (e.g., ejaculate biochemistry and sperm, genitalia and female reproductive tract morphology). Here, we resolve how sex-specific traits and their interactions contribute to key reproductive events and outcomes related to competitive fertilization success, including traits known to have experienced rapid diversification. Our results provide novel insights into the operation and complexity of PSS and demonstrate that the processes of sperm competition and cryptic female choice are not independent selective forces.

Why do females of socially monogamous species engage in extra-pair copulations? This long-standing question remains a puzzle, because the benefits of female promiscuous behavior often do not seem to outweigh the costs. Genetic constraint models offer an answer by proposing that female promiscuity emerges through selection favoring alleles that are either beneficial for male reproductive success (intersexual pleiotropy hypothesis) or beneficial for female fecundity (intrasexual pleiotropy hypothesis). A previous quantitative genetic study on captive zebra finches, Taeniopygia guttata, reported support for the first, but not for the second hypothesis. Here, we re-examine both hypotheses based on data from lines selected for high and low male courtship rate. In contrast to previous conclusions, our new analyses clearly reject the hypothesis that male and female promiscuity are genetically homologous traits. We find some support for a positive genetic correlation between female promiscuity and fecundity. This study also shows that the behavioral outcome of extra-pair courtships primarily depends on individual-specific female preferences and not on the "attractiveness" of the social mate. In contrast, patterns of paternity are strongly influenced by the social partner and the pair bond, presumably reflecting variation in copulation behavior, fertility, or sperm competitiveness.

The cephalopods (Mollusca: Cephalopoda) are an exceptional class among the invertebrates, characterised by the advanced development of their conditional learning abilities, long-term memories, capacity for rapid colour change and extremely adaptable hydrostatic skeletons. These traits enable cephalopods to occupy diverse marine ecological niches, become successful predators, employ sophisticated predator avoidance behaviours and have complex intraspecific interactions. Where studied, observations of cephalopod mating systems have revealed detailed insights to the life histories and behavioural ecologies of these animals. The reproductive biology of cephalopods is typified by high levels of both male and female promiscuity, alternative mating tactics, long-term sperm storage prior to spawning, and the capacity for intricate visual displays and/or use of a distinct sensory ecology. This review summarises the current understanding of cephalopod reproductive biology, and where investigated, how both pre-copulatory behaviours and post-copulatory fertilisation patterns can influence the processes of sexual selection. Overall, it is concluded that sperm competition and possibly cryptic female choice are likely to be critical determinants of which individuals' alleles get transferred to subsequent generations in cephalopod mating systems. Additionally, it is emphasised that the optimisation of offspring quality and/or fertilisation bias to genetically compatible males are necessary drivers for the proliferation of polyandry observed among cephalopods, and potential methods for testing these hypotheses are proposed within the conclusion of this review. Further gaps within the current knowledge of how sexual selection operates in this group are also highlighted, in the hopes of prompting new directions for research of the distinctive mating systems in this unique lineage.

In more than 75 % bird species, extra-pair paternity (situation, when at least one extra-pair young in the nest is sired by other male than a social partner of female) has been found. While male interset in attending extra-apir copulations (EPC) seems to be intuitive (more offsring sired), female motivation to engage in EPC are much less clear and obvious. Therefore, many adaptive hypotheses have been proposed to explain female proscuity. Adaptive hypothese state, that female benefits from this behaviour (higher genetic quality of offspring). The empirical evidence for such benefits, however, are missing and adaptive hypotheses remain a controversial topic. This has led to the emergence of non-adaptive hypothesis, that assume that EPC can evolve as a by-product of selection on other trait and female may not benefit from this behaviour. However, non-adaptive hypotheses are often neglected. Aim of this bachelor thesis is to take into account benefits and costs for both sexes and to point out some of the limitations of studies on EPC. Key words: Extra-pair paternity, extra-pair copulations, promiscuity, adaptive hypothesis, nonadaptive hypothesis, sexual selection, limitation of studies

Men have evolved to exhibit a desire for chastity and sexual fidelity and an abhorrence of promiscuity in long-term mates. We investigated whether these preferences manifest themselves even in an unlikely situation (prostitution) by observing men's behavior. We considered 8817 prostitutes under age 45 who worked in Indonesian cities in 2002–2004. We measured female promiscuity by experience in prostitution and applied OLS to determine whether clients paid more to less experienced prostitutes. After controlling for a set of characteristics of prostitutes and clients, we found that compared to prostitutes with an experience ≤ 1 year, prostitutes with an experience of 2–4 years earned 4.2% less, and those with an experience > 4 years earned 7.7% less. The difference is great because a value of 4.2% is just under the daily expenditure per capita on food. The relationship was more pronounced for prostitutes of high fertile age and for prostitutes with greater negotiability. It seems that the preferences are strongly built in men's psychology.

Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa1. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited1,2. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments3,4 in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences5–9. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male–male competition and female choice as discrete processes.

Cyclic changes in women's sexual desire are consistent with an ancestral pattern in which hormonal shifts around ovulation prime behavioral patterns. We use comparative primate data to evaluate the plausibility of a prominent hypothesis in evolutionary psychology, that cyclic variation in women's preferences for high-quality men leads them to seek out extra-pair sex at times of high conception risk. Our review suggests little reason to invoke substantially different reproductive strategies for human females versus other monogamous primates, which are distinguished behaviorally and morphologically from species that have adapted to female promiscuity. While cuckoldry clearly exists in human pair bonds, we conclude that its potential to transform female sexual strategies, or male morphology, has been overemphasized.

Objectives This project investigated paternity among 14 sets of twins born into a colony of ring-tailed lemurs (Lemur catta) on St. Catherines Island, GA. Female L. catta commonly mate with >1 male, and twins of different sexes confirm that dizygotic twinning can occur in this species. However, no study has previously evaluated twins using genetic data to measure the proportion of mono versus dizygotic twinning in L. catta, and no study has tested for heteropaternity (sirehood by two different males) in this species. We predicted that L. catta would show a predominance of dizygosity and evidence for heteropaternity. Materials and methods Paternity was determined for 28 infants (14 sets of twins) via paternity exclusion analyses using 10 polymorphic microsatellite markers, and data were collected on sexual behavior across four mating seasons during the first cycle of mating in each year, which overlapped with the conceptive periods of these infants. Results All twins were found to be dizygotic, as evidenced by dissimilar multilocus genotypes between the two infants of each twin pair. Heteropaternity was found in 3 of 14 (21% of) twin pairs, whereas the remaining 11 pairs of twins (79%) shared the same sire. In one case of heteropaternity, one sire was a resident male, and one sire was an extra-group male. An extra-group male also sired one of the same-sire twin pairs. All other sires of twins were group residents. Discussion Female multiple mating, which is common to many primates including L. catta, can be viewed as an adaptive reproductive strategy whose function-in addition to fertility assurance or stimulating sperm competition-may be to increase the genetic diversity of a female's offspring, even among infants born in the same birth event. Therefore, during the course of primate evolution, the adaptive benefits of heteropaternity would be expected to have contributed to positive selection for female promiscuity.

In a field study of Leon Springs pupfish Cyprinodon bovinus, two questions about female promiscuity were investigated. First, were females selective in the males with whom they spawned or were they unselective, spawning randomly among males? Second, how promiscuous were the females, i.e. with how many males did they spawn? If simply spawning with many males maximized a female's reproductive success, then females might be expected to spawn randomly with as many males as possible. Alternatively, if females were selective but engaged in multiple mating, they would limit their spawning to preferred males. In the only wild population of this endangered fish, breeding males defend closely associated territories in the shallow margins of a single desert pool. No territories were observed elsewhere in the pool. Therefore, all territorial males were present simultaneously and females could survey all of them, depositing any number of eggs with one, a few or many males. Rather than spawning randomly, females surveyed many males first, visited relatively few males and ultimately spawned with a small fraction of those available males. With increasing numbers of spawns, however, females increased the number of different mates with whom they spawned. Thus, females showed a bet-hedging tactic of having a narrow mate preference while also laying eggs in the territories of other males, possibly to reduce egg predation and to avoid inbreeding.

Understanding how animals recognize their kin has been a major challenge in biology. Most animals use one of 2 mechanisms: "familiarity" whereby kin are remembered from interactions early in life, such as in a nest, or "phenotype matching" whereby putative kin are compared with a template of what kin should look, smell, or sound like. Cross-species studies suggest that there is a link between which of these 2 mechanisms are used and the degree of female promiscuity (multiple mating). Phenotype matching is more likely to be used by promiscuous species because these species have lower average brood relatedness than monogamous species and familiarity is thus an unreliable cue of relatedness. However, it is unclear if this relationship holds within species, across populations that differ in their degree of promiscuity. Here, we take advantage of variation in brood relatedness across populations of guppies (Poecilia reticulata) to examine the relationship between kin recognition mechanisms and multiple mating within a single species. Contrary to the established hypothesis, we show that variation in recognition mechanism across populations is not governed by multiple mating. Instead, our data show that kin recognition, quantified as association preferences for shoalmates, is strongest when brood relatedness is high, consistent with Hamilton’s rule, but multiple mating does not otherwise influence the specific recognition mechanism used.

A recent comparative analysis of passerine birds found that the frequency of extra-pair paternity was positively associated with neutral genetic diversity. It has been hypothesised that migratory species have more extra-pair paternity than resident species, so we reanalysed the same comparative data set to test whether migration distance could also explain variation in genetic diversity. In this comparative analysis of 19 local populations from 18 passerine species, spanning year-round residents to long-distant migrants, we found that migration distance was positively correlated with sequence diversity at homologous nuclear Z-linked (sex) introns, but not with autosomal intronic diversity. This pattern contrasts with that of extra-pair paternity in the previous study, where extra-pair paternity was positively associated with autosomal diversity and not Z-linked diversity. We discuss several possible explanations for the correlation between Z-linked diversity and migration distance; effects that are specific to sex-linked genetic diversity may occur if migratory behaviour implies different selective regimes in the sexes or affects population structuring. These results suggest that significant amounts of genetic diversity at sex chromosomes and autosomes are shaped by different processes, and should therefore be analysed and interpreted independently in population genetics studies. The final version of this research has been published in Ethology Ecology and Evolution. © 2016 Taylor & Francis

Sperm competition theory has traditionally focused on how male allocation responds to female promiscuity, when males compete to fertilize a single clutch of eggs. Here, we develop a model to ask how female sperm use and storage across consecutive reproductive events affect male ejaculate allocation and patterns of mating and paternity. In our model, sperm use (a single parameter under female control) is the main determinant of sperm competition, which alters the effect of female promiscuity on male success and, ultimately, male reproductive allocation. Our theory reproduces the general pattern predicted by existing theory that increased sperm competition favors increased allocation to ejaculates. However, our model predicts a negative correlation between male ejaculate allocation and female promiscuity, challenging the generality of a prevailing expectation of sperm competition theory. Early models assumed that the energetic costs of precopulatory competition and the level of sperm competition are both determined by female promiscuity, which leads to an assumed covariation between these two processes. By modeling precopulatory costs and sperm competition independently, our theoretical framework allows us to examine how male allocation should respond independently to variation in sperm competition and energetic trade-offs in mating systems that have been overlooked in the past.

Polyandry is a source of sexual conflict and males often try to limit female promiscuity. Consequently, male manipulation of receptivity via antiaphrodisiacs and copulatory plugs that prevent female remating can be a source of sexual conflict. This sexual conflict may be intensified when females must remate for fertility insurance. Male red-sided garter snakes produce a large, gelatinous copulatory plug that has been proposed to 1) physically prevent remating and 2) contain an antiaphrodisiac that reduces female receptivity. These males may become sperm depleted because of their dissociated reproductive pattern. If a female mates with a sperm deficient male and is also rendered unreceptive to further mating, then this represents a serious conflict. We tested whether female remating frequency is affected when females are mated with a male that produces a sperm-less copulatory plug. We show that females are significantly more likely to remate after mating with vasectomized males than intact males, even though vasectomized males still produce a copulatory plug. These results suggest that the ejaculate material of the plug does not contain an antiaphrodisiac. Instead, females may use sperm as a cue for post-copulatory mate assessment and seek to remate for the direct benefit of fertility insurance if they have mated with sperm-depleted males.

In species with biparental care, males may be under selection to adjust the amount of care they provide for their offspring in response to losses in paternity. Previous work on birds and fishes provide mixed empirical evidence for facultative adjustments in male care to losses in paternity. One potential reason for this inconsistency is that males need access to reliable cues of losses in paternity, and that it might be difficult to assess what cues, if any, are used by males. Here we manipulated three cues of losses in paternity in the burying beetle Nicrophorus vespilloides: the presence of a (dead) rival male (N = 44), the temporary absence of the female (N = 41) and the presence of a rival male's cuticular hydrocarbons on the female (N = 44). We focused on these three cues because there is evidence that males respond to these cues in other species and there is also evidence that our study species responds to these cues in other contexts. We found no effect of the three cues on the amount of direct or indirect care provided by the male, male weight change, or the number and weight of offspring. Our results provide no evidence that single male parents adjust their investment in the current brood based on cues of losses in paternity. As previous work showed that most wild females arriving on a carcass already store sperm, it is likely that males have evolved a fixed response to female polyandry by mating very frequently with the female.

Reproductive promiscuity, whereby females are fertilized by extrapair mates, is common. The frequency of extrapair fertilizations (EPFs) depends on at least three sources of variation. First, females may differ in their proneness to being fertilized by extrapair males. Second, males may differ in traits that affect realized promiscuity of females. Third, EPF decisions depend on the combined effects of the identity of social mates. Here, we relied on extensive genetic parentage analysis of the offspring of a socially monogamous bird, the barn swallow, Hirundo rustica, to assess which of the above sources of variation predict the occurrence of EPFs. When we controlled for pair composition and social mate attractiveness, EPFs covaried with morphological and coloration traits of feathers in females. As expected, females mated with highly ornamented, long-tailed males had fewer EPFs. The composition of the breeding pair also accounted for variation in EPFs, implying that the ability of individual males to secure genetic parentage varies between female mates. These results show that females differ in promiscuity, and phenotypic traits of females that are visible to males are associated with promiscuity, potentially serving as cues to prospecting males. Hence, contrary to common interpretations of the negative relationship between male sexual attractiveness and female promiscuity, it can be speculated that larger genetic parentage by highly ornamented males results from their ability to secure the less promiscuous mates rather than from females being less promiscuous when mated to them. Moreover, our study shows that EPFs also depend on the composition of the social pair, as expected if a component of female promiscuity decisions depends on genetic or behavioural compatibility with the social male mate. Our study emphasizes that female promiscuity and its phenotypic correlates, and composition of the social pair, deserve closer attention in studies of sexual selection mediated by EPFs.

Sex is good for us, but it is a compromise. For the benefit of being able to produce genetically variable offspring, we must pay the cost of passing on only half our genes to each of them. Whilst evolutionary biologists still puzzle over the precise details of why the benefits of sex so frequently seem to outweigh the costs (Neiman, Lively, & Meirmans, ), one major challenge to sexual reproduction is the fact that if we pass on only half our genetic material to each gamete, there is a strong incentive for each individual allele to try to gain an unfair representation during gamete production. Fundamental to stabilizing sex once it evolves is therefore the ability to ensure a fair meiosis. Nevertheless, this system is not perfect, and some selfish genetic elements - so-called meiotic drivers - manage to tip the meiotic scales in their favour and gain a transmission advantage (review in Burt and Trivers, ). In this issue of Molecular Ecology, Manser, Lindholm, Simmons, and Firman () demonstrate that in house mice, the effectiveness of one such harmful transmission distorter is reduced by polyandry and hence that population viability can be somewhat restored by female promiscuity.

In 1918, the British War Office introduced Regulation 40D as an amendment to the Defence of the Realm Act (DORA). The short- lived regulation allowed the state to remand and imprison a woman for the transmission of venereal disease to a member of His Majesty's armed forces. This paper examines discourses on national security and female promiscuity surrounding the enactment of Regulation 40D and the prosecutions under this controversial measure. The paper argues that the regulation was merely symbolic, and that it empowered magistrates to assess, judge and ultimately control women's sexual behaviour in the name of national security.

Male expected reproductive success can be enhanced by increased mating success (mate number) or, when females can mate multiply, by increased mating exclusivity (i.e., reduced partner promiscuity). A positive or negative covariance between these two mating outcomes could substantially increase or decrease overall variation in male expected reproductive success, yet the relationship between these mating outcomes is relatively understudied. We examined this relationship and the influence of male personality traits, female personality traits, and the social environment on mating outcomes in stream water striders, Aquarius remigis, at two experimental sex ratios: equal and 2:1 male-biased. To our knowledge, this study is the first to quantify this full set of effects. We found that mating frequency (mating success) and mating exclusivity were positively correlated in the male-biased treatment, but were not related at equal sex ratios. At both sex ratios, males that were more active and aggressive had both higher mating frequency and higher mating exclusivity. A male’s effective mating (the product of mating frequency and mating exclusivity) was also higher if on average he mated with females that tended to hide in refuges (and were presumably less available for future matings). Finally, males that were more often in pools with extremely aggressive (“hyperaggressive”) males actually had increased mating exclusivity, potentially because hyperaggression reduced average female promiscuity. This study highlights the importance of considering mating outcomes beyond mating success and examining the simultaneous contribution of male behaviours, female behaviours and social factors to mating dynamics.

Although laboratory measurements of whole-animal performance have become a standard tool in evolutionary biology, if and how interindividual variation in performance translates into differential fitness remains poorly understood. Particularly rare are studies that have connected performance to mating and reproductive success in the field. In this study, we use DNA microsatellite parentage analyses to study the fitness gradient in a colour-polymorphic lizard, Podarcis melisellensis. We report on two surprising findings. First, contrary to our expectations, individual sprint speed and bite force capacity correlated negatively, not positively, with male mating and reproductive success. Second, we found an unexpected degree of promiscuity in females. Also, contrary to traditional parental investment theory, the variation in mating success and reproductive success was as high in females as in males. Our results call for a better integration of whole-animal performance and life history traits, and for a reconsideration of the ideas on the likeliness of sexual selection acting on female phenotypes.

Conflicts between family members are expected to influence the duration and intensity of parental care. In mammals, the majority of this care occurs as resource transfer from mothers to offspring during gestation and lactation. Mating systems can have a strong influence on the severity of familial conflict--where female promiscuity is prevalent, conflict is expected to be higher between family members, causing offspring to demand more resources. If offspring are capable of manipulating their mothers and receive resources in proportion to their demands, resource transfer should increase with elevated promiscuity. We tested this prediction, unexplored across mammals, using a comparative approach. The total durations of gestation and lactation were not related to testes mass, a reliable proxy of female promiscuity across taxa. Offspring growth during gestation, however, and weaning mass, were positively correlated with testes mass, suggesting that offspring gain resources from their mothers at faster rates when familial conflict is greater. During gestation, the relationship between offspring growth and testes mass was also related to placenta morphology, with a stronger relationship between testes mass and growth observed in species with a less invasive placenta. Familial conflict could have a pervasive influence on patterns of parental care in mammals.

Population viscosity can have major consequences for adaptive evolution, in particular for phenotypes involved in social interactions. For example, population viscosity increases the probability of mating with close kin, resulting in selection for mechanisms that circumvent the potential negative consequences of inbreeding. Female promiscuity is often suggested to be one such mechanism. However, whether avoidance of genetically similar partners is a major selective force shaping patterns of promiscuity remains poorly supported by empirical data. Here, we show (i) that fine-scale genetic structure constrains social mate choice in a pair-bonding lizard, resulting in individuals pairing with genetically similar individuals, (ii) that these constraints are circumvented by multiple mating with less related individuals and (iii) that this results in increased heterozygosity of offspring. Despite this, we did not detect any significant effects of heterozygosity on offspring or adult fitness or a strong relationship between pair relatedness and female multiple mating. We discuss these results within the context of incorporating the genetic context dependence of mating strategies into a holistic understanding of mating system evolution.

Mating strategies are sets of decisions aimed at maximizing reproductive success. For male animals, the fundamental problem that these strategies address is attaining mating access to females in a manner that maximizes their chances of achieving paternity. For chimpanzees (Pan troglodytes), despite substantial interest in mating strategies, very little attention has been paid to the most fundamental problem that mating strategies need to solve: finding mates. Only a single model, Dunbar’s general model of male mating strategies, exists to explain mate-searching behaviour in chimpanzees. Under this model, males in most populations are regarded as pursuing a ‘roving’ strategy: searching for and sequestering fertile females who are essentially passive with respect to mate searching. The roving mating strategy is an assumption deeply embedded in the way chimpanzee behaviour is considered; it is implicit in the conventional model for chimpanzee social structure, which posits that male ranging functions both to monitor female reproductive state and to ward these females from other groups of males through collective territoriality: essentially, ranging as mating effort. This perspective is, however, increasingly at odds with observations of chimpanzee behaviour. Herein, I review the logic and evidence for the roving-male mating strategy and propose a novel alternative, a theoretical framework in which roving is a strategy pursued by female chimpanzees in order to engage successfully in promiscuous mating. Males, unable to thwart this female strategy, instead maximise the number of reproductive opportunities encountered by focusing their behaviour on countering threats to health, fertility and reproductive career. Their prolonged grooming bouts are seen, in consequence, as functioning to mitigate the negative impacts of socially induced physiological stress. In this new framework, the roving-male strategy becomes, at best, a ‘best of a bad job’ alternative for low-ranking males when faced with high levels of competition for mating access. Male chimpanzees do not search for mates, but for one another, for food, and, at times, for rivals in other communities. To the extent that female promiscuity functions to counter infanticide risk, mate searching by female chimpanzees—and any associated costs—can be seen as an unavoidable consequence of male sexual coercion. This novel framework is a better fit to the available data than is the conventional account. This review highlights the desperate need for additional work in an area of chimpanzee biology that has been somewhat neglected, perhaps in part because assumptions of roving males have remained unquestioned for too long. It also highlights the need, across taxa, to revisit and revise theory, and to test old assumptions, when faced with contrary data.

The hypophysis influences biological functions in mammals at various levels, and its volumetric variation in Chiroptera is recently well known. We explored the relation of the hypophysis size as a whole (Hyp) and its separate components, adenohypophysis (Adh) and neurohypophysis (Neh), from 96 species of bats (Yinpterochiroptera and Yangochiroptera), with social (roosting association), reproductive (testes mass, mating system, female promiscuity), body size (body mass) and foraging (diet) variables (when available for the sampled species), through ANCOVA and linear regressions analyses. We also explored the phylogenetic legacy of the volumetric changes of Hyp, Adh and Neh over a well-resolved phylogenetic tree, through Phylogenetically independent contrasts analysis, phylogenetic signal, and character optimizations. Hyp, Adh, Neh volumes and testes mass showed significant relation with body mass. When body mass effect was excluded, Hyp, Adh and Neh showed no significant relation with testes mass nor significant differences within roosting association, mating system and female promiscuity variables. However, Hyp, Adh and Neh volumes showed a pattern with diet, probably related to the regulatory role of the hypophysis at the endogenous protein metabolism in Mammals. The significant phylogenetic effect at linear regressions of Hyp, Adh and Neh volumes against body mass suggests the hypophysis volume and the body mass has coevolved, which was also supported by the significant phylogenetic signal and the optimizations considering body mass. Optimizations excluding body mass also showed significant phylogenetic signal, demonstrating that the volumetric changes bear phylogenetic information beyond body size. Our results suggest that the hypophysis size variations in bats are rather explained by phylogenetic legacy, as phylogenetic inertia linked to the ecology of the ancestors of the different clades, than current ecological aspects related to the natural history of the extant species.

As proposed by the ‘good parent model’ for evolution of secondary male ornamentation, secondary ornaments may signal male provisioning rates and, therefore, direct benefit to females. On the other hand, male parental care intensity can potentially be affected by the occurrence of extra-pair offspring in its nest. According to ‘parental investment theory’, males that lose paternity in their nests should reduce their parental care. In this study, we analyse potential relationships between intensity of parental care, male ornamentation, the occurrence of extra-pair paternity and male extra-pair fertilisation success in the scarlet rosefinch Carpodacus erythrinus. Our results based on 50 observed nests indicate no effect of paternity loss on the rate of food provisioning to nestlings in scarlet rosefinches. Simultaneously, we found no evidence for an association between male ornamentation and male provisioning rates. The only male trait associated with provisioning was the ability to sire extra-pair offspring. Our data indicate that direct selection against female promiscuity is weak or absent in rosefinches.

Sperm storage is widespread in many vertebrate groups, and it is frequently associated with promiscuous mating systems. Chelonian species are one of the most outstanding examples of a promiscuous group capable of long-term sperm storage; specialized structures have evolved within the oviducts of these vertebrates to ensure sperm vitality across reproductive cycles. Thus far, few studies have investigated the factors regulating multiple paternity, sperm usage by females and paternity distribution in successive clutches. This study aimed to investigate the effect of mating order on male mounting and reproductive success in Testudo hermanni hermanni, combining behavioural and genetic data. A series of planned matings were performed, within which experimental females were mated sequentially to two different males under controlled conditions. Observations conducted during experimental matings revealed that courtship displays did not significantly differ between the first and second males to mate with a female. Interactions ending with a mount were characterized by a significantly higher intensity and occurrence of determinate courtship behaviours, for example biting and running after the female. Paternity analysis performed on hatchlings produced from experimental females revealed that 46 % of the clutches were multi-sired. A significant contribution of previous years' partners was still found, thus confirming the long-term sperm storage within the female oviduct in this species. Finally, mating order did not significantly affect the reproductive success of experimental males during the on-going reproductive season.

When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity, (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour.\ud \ud

Female promiscuity can generate postcopulatory competition among males, but it also provides the opportunity for exploitation of rival male ejaculates. For example, in many insect species, male seminal fluid proteins (Sfps) transferred in a female's first mating stimulate increased fecundity and decreased receptivity to remating. Subsequent mates of females could potentially take advantage of the effects of the first male's Sfps and strategically reduce investment in their own ejaculate. We compared postmating responses (fecundity and sexual receptivity) of Drosophila melanogaster females after their first (virgin) matings (V), to the responses of females remating (M) 24 h after their first mating. The results show that M matings fail to boost fecundity and, thus, males are unlikely to gain fitness from transferring Sfps whose sole function—in V matings—is fecundity-stimulation. However, males can protect their likelihood of paternity in M matings through the transfer of receptivity-inhibiting Sfps. The levels of a fecundity-stimulating Sfp (ovulin) were significantly lower in M females relative to V females, at the same time point shortly after the end of mating. In contrast, the levels of a key receptivity-inhibiting Sfp (sex peptide) were the same in M and V females. These results support the hypothesis that males can adaptively tailor the composition of proteins in the ejaculate, allowing a male to take advantage of the fecundity-stimulating effects of the previous male's ovulin, yet maintaining investment in sex peptide. Furthermore, our results demonstrate sophisticated protein-specific ejaculate manipulation.

Science progresses through ideas or hypotheses; novel ways of viewing the world. If those ideas survive testing, then they are considered ‘the truth’, or more crucially, truth-for-now, for the essence of science is that if a new idea provides a better explanation of the way the world is, the truth changes. Darwin’s idea of evolution by natural selection, published as the Origin in 1859, replaced the earlier truth of physico- or natural-theology introduced by John Ray in 1691. Despite resistance by the church, Darwin’s truth gained widespread acceptance, in part due to the efforts of T. H. Huxley, who on reading the Origin said ‘How extremely stupid not to have thought of that!’ Despite natural selection’s enormous explanatory power, there were certain phenomena it apparently could not explain, including female promiscuity. It was only in the 1960s when natural selection was viewed as operating explicitly on individuals (rather than populations or groups), that this changed. Rather than being a cooperative venture between the sexes, sexual reproduction was now viewed in terms of conflicts of interests, and in so doing provided an explanation for female promiscuity (albeit in a male-biased sort of way). Until this point, sexual selection had been concerned exclusively with mate acquisition. With an evolutionary perspective focussing on individuals, it was recognized that sexual selection might continue after insemination, and that rather than competing for partners, males compete for fertilizations. Later it was acknowledged that females, through cryptic processes can also influence the outcome of sperm competition. Today, post-copulatory sexual selection provides explanations for many previously bewildering reproductive traits, including the extraordinary diversity in male and female genitalia, the design of spermatozoa and ova, of seminal fluid and of copulation behaviour itself

Mating systems have a profound influence on the probability of conflict occurring between the sexes. Promiscuity is predicted to generate sexual conflict, thereby driving the evolution of male traits that harm females, whereas monogamy is expected to foster reproductive cooperation, thus rendering such traits redundant. We tested these predictions using experimentally evolved Drosophila pseudoobscura subject to different mating systems. Female survival was not influenced by the mating system treatment of her partner. However, females continuously housed with males evolving under elevated opportunities for female promiscuity produced fewer total progeny, but a relatively greater number of progeny early in their lives, than females housed with males evolving under obligate monogamy. We also found that promiscuous males courted females more frequently than monogamous males. Variation in male courtship frequency and progeny production patterns among treatments reinforces the critical importance of mating system variation for sexual conflict, during both pre- and post-copulatory interactions.

Female promiscuity is common among mammals but its advantages, particularly for marsupials, remain unclear. Using microsatellite DNA from pouch young of known mothers, we identified the most likely fathers of 25 wild spotted-tailed quolls (Dasyurus maculatus) from six litters. We aimed to determine whether young within the same litter had different fathers, and whether breeding success of males was associated with large body mass (consistent with inter-male competition) or scrotal width (consistent with sperm competition). We also explored the possible influence of promiscuity on relatedness within litters. Finally, we used data on paternity and relatedness to make inferences regarding movement and dispersal. Four litters were sired by more than one male, and three males sired offspring in more than one litter. Known fathers had higher body mass, but not scrotal width, than males of unknown paternity status, suggesting that males may compete for access to females. Sires were less related to dams than expected by chance, and litters with multiple paternity had lower relatedness than litters sired by a single male. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 1–7.

The application of molecular genetic techniques has revolutionized our view of avian mating systems. Contrary to prior expectations, birds are only very rarely sexually monogamous, with ‘extra-pair offspring’ found in approximately 90% of species. Even among socially monogamous species, over 11% of offspring are, on average, the result of extra-pair paternity (EPP). Based on over 150 molecular genetic studies of EPP in birds, we review two topical areas: (i) ecological explanations for interspecific variation in the rate of EPP; and (ii) evidence bearing on the adaptive function of EPP. We highlight the remaining challenges of understanding the relative roles of genes and ecology in determining variation between taxa in the rate of extra paternity, and testing for differences between extra-pair offspring and those sired within-pair.