Female Choice Research Articles

Psychophysical measurements during the priming of intrasexual competition.

Psychophysical measurements during the priming of intrasexual competition.

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers.

Gamete size variation between the sexes is central to the concept of sex roles, however, to what extent gamete size variation within the sexes relates to sex role variation remains unclear. Comparative and theoretical studies suggest that, when clutch size is invariable, polyandry is linked to a reduction of egg size, while increased female-female competition for mates favors early breeding when females cannot monopolize multiple males. To understand whether and how breeding phenology, egg size, and mating behavior are related at the individual level, we studied the reproductive histories of 424 snowy plover females observed in the wild over a 15-year period. Egg size, but not polyandry, were highly repeatable for individual females. Consistent with theoretical predictions, we found that polyandrous females were the earliest breeders and that early clutches contained smaller eggs than clutches initiated later. Neither egg size nor mating behavior showed clear signs of an age-related deterioration, on the contrary, prior experience acquired either through age or local recruitment enabled females to nest early. Taken together, these results suggest that gamete size variation is not linked to mating behavior at the individual level, and, consequently, the adaptive potential of such variation appears to be limited.

Odor cues rather than personality affect tadpole deposition in a neotropical poison frog.

Animals constantly need to evaluate available external and internal information to make appropriate decisions. Identifying, assessing, and acting on relevant cues in contexts such as mate choice, intra-sexual competition, and parental care is particularly important for optimizing individual reproductive success. Several factors can influence decision-making, such as external environmental cues and the animal's own internal state, yet, we have limited knowledge on how animals integrate available information. Here, we used an entire island population (57 males, 53 females, and 1,109 tadpoles) of the neotropical brilliant-thighed poison frog Allobates femoralis to investigate how 2 factors (olfactory cues and personality traits) influence the ability of males to find and use new resources for tadpole deposition. We experimentally manipulated the location of tadpole deposition sites and their associated olfactory cues, and repeatedly measured exploration and boldness in adult males. We further reconstructed tadpole deposition choices via inferred parent-offspring relationships of adult frogs and tadpoles deposited in our experimental pools using molecular parentage analysis. We found that the discovery and use of new rearing sites were heavily influenced by olfactory cues; however, we did not find an effect of the measured behavioral traits on resource discovery and use. We conclude that in highly dynamic environments such as tropical rainforests, reliable external cues likely take priority over personality traits, helping individuals to discover and make use of reproductive resources.

Off with her hair: Intrasexually competitive women advise other women to cut off more hair

Intrasexual competition between women is often covert, and targets rivals' appearance. Here we investigate appearance advice as a vector for female intrasexual competition. Across two studies (N = 192, N = 258) women indicated how much hair they would recommend hypothetical clients have cut off in their hypothetical salon. Clients varied in their facial attractiveness (depicted pictorially), the condition of their hair, and how much hair they wished to have cut off. Participants also provided self-report measures of their own mate value and intrasexual competitiveness. In both studies, participants' intrasexual competitiveness positively predicted how much hair they recommended clients have cut off, especially when the hair was in good condition and the clients reported wanting as little as possible cut off – circumstances wherein cutting off too much hair is most likely to indicate sabotage. Considering data across both collectively, women tended to recommend cutting the most hair off clients they perceived to be as attractive as themselves. These data suggest that just like mating, intrasexual competition may be assortative with respect to mate value. They also demonstrate that competitive motives can impact female-female interactions even in scenarios which feature no prospective mates, and are nominally unrelated to mate guarding or mating competition.

Sexual selection in seaweed? Testing Bateman's principles in the red alga Gracilaria gracilis.

In anisogamous species, sexual selection is expected to be stronger in males. Bateman's principles state that the variance in (i) reproductive and (ii) mating success is greater for males, and (iii) the relationship between reproductive success and mating success (the Bateman gradient) is also stronger for males than for females. Sexual selection, based on Bateman's principles, has been demonstrated in animals and some angiosperms, but never in a seaweed. Here we focus on the oogamous haploid-diploid rhodophyte Gracilaria gracilis in which previous studies have shown evidence for non-random mating, suggesting the existence of male-male competition and female choice. We estimated mating and reproductive success using paternity analyses in a natural population where up to 92% of fertilizations occurred between partners of that population. The results show that the variance in mating success is significantly greater in males than in females and that the Bateman gradient is positive only in males. Distance to female partners also explains a minor part of the variance in male mating success. Although there is no evidence for sexual dimorphism, our study supports the hypothesis that sexual selection occurs in G. gracilis, probably on male traits, even if we cannot observe, characterize or quantify them yet.

Parlare di sessualità. Dove e come?

Family counselling clinics are a unique Italian social and health service. They were created in the 70s to deal with sex education, contraception, abortion, sexually transmitted diseases, gender identity and violence. The access is for free also for minors because Italian Law 194/78 grants minors the right to make autonomous contraceptive and sexual choices. Many family counselling clinics deal with sex education also in schools. They also have specific spaces called Spazio Giovani, recognized in the recent LEA (essential levels of assistance), in which young people can meet counsellors without any appointment and can discuss with them. Collaboration, exchange of information and shared training with paediatricians are desirable practices. The creation of listening opportunities on sexuality can break the internet noise and promote mental and sexual health in adolescents. Today’s boys and girls have access to more information about sex and sexuality than previous generations. They are likely to encounter everywhere narratives about sex, often with contents that are inappropriate for their age. This is the space that should be fitted into to make teenagers feel less alone, to let them dream and to convey them the pleasure of having relationships that are based on affection and support their mental health.

Mating in the cold. Prolonged sperm storage provides opportunities for forced copulation by male bats during winter.

In a wide range of heterothermic mammals, hibernation interrupts the reproductive cycle by forcing reproductive delays. In hibernating bats with delayed fertilization, an opportunity for sperm competition is enhanced by extending a time-window between copulations and fertilization. In order to achieve greater fertilization success, males are expected to show adaptations for sperm competition by increasing their opportunities for mating over an extended period. We aimed to clarify the physiological and behavioral characteristics of male bats experiencing increased risks of sperm competition. We investigated the characteristics of the reproductive cycle of the little horseshoe bat (Rhinolophus cornutus), and examined whether males retain reproductive physiology related to sexual behavior, and attempt to copulate with females even during the hibernation period. Field observations and histological examinations of the reproductive cycle confirmed that females, having mated in the autumn, store spermatozoa in the uterus during hibernation and give birth in the early summer to just one offspring per year, thus males face a low certainty of successful fertilization. Although their testes regressed rapidly and their testosterone levels were lower during winter than in autumn, males stored motile spermatozoa in their cauda epididymides from autumn throughout the winter. During hibernation, we found that males occasionally aroused from torpor and attempted to mate forcibly with torpid females. Forced copulations appear to increase a male's chances of obtaining a mate while avoiding pre-copulatory female choice. Epididymal sperm storage could be advantageous for males in allowing them to extend their potential mating period even though their testes have regressed. We also found that some hibernating nulliparous females were ready for fertilization in spring after hibernation, whereas few parous females appeared in the same roost. In contrast to males, forced copulations would be maladaptive for females because they cannot opt for higher-quality males while in torpor. Females that have experienced sexual coercion when young may subsequently avoid hibernacula where adult males are present.

From problem‐centered to centering relationalities: Engagements with disability and sexuality in India

AbstractThis article analyses how the sites of disability activism, special education, and online‐matchmaking approach the sexuality of disabled people in India. It argues that across these distinct yet overlapping sites, the sexuality of disabled people is engaged as a problem in need of a fix, which ultimately leads to the narrowing of disabled people's sexual choices, behaviors, and identities. The article suggests that when these field‐sites move away from a problem‐centered approach which focuses on looking for normative solutions and instead engage in the process of “problematization” by facilitating the sexuality of disabled people, they end up opening non‐normative, uncertain, yet perhaps more fulfilling sexual opportunities for disabled people.

IMPACTS OF CHELIPED MORPHOLOGY ON MATE SELECTION OF AN INVASIVE CRAYFISH, THE RED SWAMP CRAYFISH (PROCAMBARUS CLARKII)

Abstract The red swamp crayfish, Procambarus clarkii, is a large-bodied crayfish that is native to northeastern Mexico and the south-central United States. The extensive breeding season and the r-selected characteristics of this species allow it to produce a large number of offspring. Despite the extensive research on the invasive potential of this organism, some behavioral aspects of the mating system have not been well-studied. We investigated how cheliped morphology impacts female choice and copulation behavior by manipulating three male traits: chela presence, function, and chela-body size ratio. Females showed no preference for males based on any of the visual traits examined, and copulations were infrequent and not indicative of female preference for a male phenotype. Chela function and chela-body size ratio impacted male copulation attempts, suggesting male dominance and aggression as a potentially significant component in the mating system of P. clarkii. Finally, our we encourage further research to include other visual and chemical stimuli to truly understand the crayfish mating system and the role of female choice.

Social regulation of androgenic hormones and gestural display behavior in a tropical frog

Many animals use forms of gesture and dance to communicate with conspecifics in the breeding season, though the mechanisms of this behavior are rarely studied. Here, we investigate the hormone basis of such visual signal behavior in Bornean rocks frogs (Staurois parvus). Our results show that males aggregating at breeding waterfalls have higher testosterone (T) levels, and we speculate that this hormone increase is caused by social cues associated with sexual competition. To this end, we find that T levels in frogs at the waterfall positively predict the number waving gestures—or “foot flags”—that males perform while competing with rivals. By contrast, T does not predict differences in male calling behavior. In these frogs, vocal displays are used largely as an alert signal to direct a rival's attention to the foot flag; thus, our results are consistent with the view that factors related to reproductive context drive up T levels to mediate displays most closely linked to male-male combat, which in this case is the frog's elaborate gestural routine.

Male size does not affect the strength of male mate choice for high-quality females in Drosophila melanogaster.

Theory predicts that the strength of male mate choice should vary depending on male quality when higher-quality males receive greater fitness benefits from being choosy. This pattern extends to differences in male body size, with larger males often having stronger pre- and post-copulatory preferences than smaller males. We sought to determine whether large males and small males differ in the strength (or direction) of their preference for large, high-fecundity females using the fruit fly, Drosophila melanogaster. We measured male courtship preferences and mating duration to show that male body size had no impact on the strength of male mate choice; all males, regardless of their size, had equally strong preferences for large females. To understand the selective pressures shaping male mate choice in males of different sizes, we also measured the fitness benefits associated with preferring large females for both large and small males. Male body size did not affect the benefits that males received: large and small males were equally successful at mating with large females, received the same direct fitness benefits from mating with large females, and showed similar competitive fertilization success with large females. These findings provide insight into why the strength of male mate choice was not affected by male body size in this system. Our study highlights the importance of evaluating the benefits and costs of male mate choice across multiple males to predict when differences in male mate choice should occur.

The effects of perceived encouragement during adolescence on female career choice.

The effects of perceived encouragement during adolescence on female career choice.

Mate-guarding success depends on male investment in a butterfly.

Males of many insects, including butterflies, produce mate-guarding devices, such as mating plugs, to prolong guarding and prevent future female matings in the male's absence. In a few butterflies, large external mate-guarding devices, that is, sphragides, occur. Gór et al. (Behaviour, 160, 2023 and 515-557) found conspicuously large size and morphological variation of mate-guarding devices within a single population of the potentially polyandrous Clouded Apollo (Parnassius mnemosyne, L.) butterfly. They termed the externally visible male-produced devices as Copulatory opening APpendices (CAP) consisting of small devices, termed small CAPs and the much larger shield (i.e. sphragis). Our aim was to reveal CAP replacement dynamics within females during their lifetime and to understand how male investment into small CAPs or shields was (i) related to CAP persistence on the female, that is securing paternity, (ii) associated with female quality, measured as size and (iii) with actual adult sex ratio. We investigated a univoltine Clouded Apollo population to estimate CAP replacement risks, using multistate survival models, in an extensive observational study through 6 years based on mark-recapture. Shields were the most frequent mate-guarding devices and were more persistent than small CAPs, often lasting for life, excluding future matings. Thus, most females bearing a shield were deprived of postcopulatory female choice, and the genetic variance in their offspring could be reduced compared to those bearing small CAPs, thus mating more often. The ratio of shields to all CAPs gradually decreased towards the end of the flight period. Males were more prone to produce a shield when mating females with wider thoraces and when the ratio of males (i.e. competition) was higher in the population. To our best knowledge, this is the first quantitative study to investigate potential factors on which male investment in mate-guarding devices may depend, and how the variation in these devices impacts CAP persistence on females.

Sperm of more colourful males are better adapted to ovarian fluids in lake char (Salmonidae).

Fish often spawn eggs with ovarian fluids that have been hypothesized to support the sperm of some males over others (cryptic female choice). Alternatively, sperm reactions to ovarian fluids could reveal male strategies. We used wild-caught lake char (Salvelinus umbla) to experimentally test whether sperm react differently to the presence of ovarian fluid, and whether any differential sperm reaction could be predicted by male breeding coloration, male inbreeding coefficients (based of 4150 SNPs) or the kinship coefficients between males and females. Male coloration was positively linked to body size and current health (based on lymphocytosis and thrombocytosis) but was a poor predictor of inbreeding or kinship coefficients. We found that sperm of more colourful males were faster in diluted ovarian fluids than in water only, while sperm of paler males were faster in water than in ovarian fluids. We then let equal numbers of sperm compete for fertilizations in the presence or absence of ovarian fluids and genetically assigned 1464 embryos (from 70 experimental trials) to their fathers. The presence of ovarian fluids significantly increased the success of the more colourful competitors. Sperm of less inbred competitors were more successful when tested in water only than in diluted ovarian fluids. The kinship coefficients had no significant effects on sperm traits or fertilization success in the presence of ovarian fluids, although parallel stress tests on embryos had revealed that females would profit more from mating with least related males rather than most coloured ones. We conclude that sperm of more colourful males are best adapted to ovarian fluids, and that the observed reaction norms suggest male strategies rather than cryptic female choice.

Host Plant Effects on Sexual Selection Dynamics in Phytophagous Insects.

Natural selection is notoriously dynamic in nature, and so, too, is sexual selection. The interactions between phytophagous insects and their host plants have provided valuable insights into the many ways in which ecological factors can influence sexual selection. In this review, we highlight recent discoveries and provide guidance for future work in this area. Importantly, host plants can affect both the agents of sexual selection (e.g., mate choice and male-male competition) and the traits under selection (e.g., ornaments and weapons). Furthermore, in our rapidly changing world, insects now routinely encounter new potential host plants. The process of adaptation to a new host may be hindered or accelerated by sexual selection, and the unexplored evolutionary trajectories that emerge from these dynamics are relevant to pest management and insect conservation strategies. Examining the effects of host plants on sexual selection has the potential to advance our fundamental understanding of sexual conflict, host range evolution, and speciation, with relevance across taxa.

Trade-offs between immunity and competitive ability in fighting ant males

BackgroundFighting disease while fighting rivals exposes males to constraints and trade-offs during male-male competition. We here tested how both the stage and intensity of infection with the fungal pathogen Metarhizium robertsii interfere with fighting success in Cardiocondyla obscurior ant males. Males of this species have evolved long lifespans during which they can gain many matings with the young queens of the colony, if successful in male-male competition. Since male fights occur inside the colony, the outcome of male-male competition can further be biased by interference of the colony’s worker force.ResultsWe found that severe, but not yet mild, infection strongly impaired male fighting success. In late-stage infection, this could be attributed to worker aggression directed towards the infected rather than the healthy male and an already very high male morbidity even in the absence of fighting. Shortly after pathogen exposure, however, male mortality was particularly increased during combat. Since these males mounted a strong immune response, their reduced fighting success suggests a trade-off between immune investment and competitive ability already early in the infection. Even if the males themselves showed no difference in the number of attacks they raised against their healthy rivals across infection stages and levels, severely infected males were thus losing in male-male competition from an early stage of infection on.ConclusionsMales of the ant C. obscurior have a well-developed immune system that raises a strong immune response very fast after fungal exposure. This allows them to cope with mild pathogen exposures without compromising their success in male-male competition, and hence to gain multiple mating opportunities with the emerging virgin queens of the colony. Under severe infection, however, they are weak fighters and rarely survive a combat already at early infection when raising an immune response, as well as at progressed infection, when they are morbid and preferentially targeted by worker aggression. Workers thereby remove males that pose a future disease threat by biasing male-male competition. Our study thus reveals a novel social immunity mechanism how social insect workers protect the colony against disease risk.

Reproductive benefits and reduced investment in parental care behavior associated with reproductive groups of males in Abudefduf troschelii.

Fishes of the family Pomacentridae present a wide diversity of mating systems, ranging from polygyny to promiscuity and from individual territorial defense to the establishment of reproductive colonies of males. The damselfish species Abudefduf troschelii has a reproductive colony mating system, in which males temporarily aggregate in reproductive areas to court and attract females. Males defend an individual territory where they receive eggs and perform paternal care behaviors for their offspring. The present study evaluated the advantages of the colonial mating system in A. troschelii. During an entire reproductive period, in a breeding colony within a rocky reef, we located, marked, geo-referenced, and measured the distances between the territories of all males. We quantified the variance among males in their patterns of paternal care investment, eggs acquired, hatching success, reproductive success, body size, and changes in body coloration. We found that males spatially distributed their nests in groups or independently (i.e., solitary nests). Nesting groups are formed by larger males that show intense nuptial coloration during the entire receptivity period. They are located centrally to the colony and consist of three to six males whose territories overlap. In contrast, small solitary males that fail to acquire or maintain nuptial coloration during the receptivity period establish their nests peripherally to the colony, away from the territories of other males. Our results highlight that the reproductive benefits of colonial nesting are unequal for males, as the spatial distribution of nests within the colony determines the reproductive success of males. Group nesting confers the highest reproductive benefits to males regarding eggs obtained, hatching success, and relative fitness and also enables males to reduce their parental investment in brood care behaviors. The preference of females for oviposition could be associated with greater intrasexual competitiveness, defense ability, body condition, or experience of group-nesting males located at the center of the colony or because their progeny will have a lower probability of predation than they would in solitary nests males.

Population‐level food availability affects postcopulatory sexual selection dynamics in the guppy

Abstract Postcopulatory sexual selection (PCSS), namely sperm competition and cryptic female choice, is typically investigated in benign environments, with a fixed number of partners, which mate at the same time intervals; all conditions that are rarely met in natural populations. Although there is increasing evidence that environmental fluctuations affect sexual selection before mating, whether and to which extent they influence postcopulatory trajectories is still little explored. PCSS was investigated in replicate populations of guppies (Poecilia reticulata) in which males and females mated after maintained for 2 weeks on either restricted (RE) or ad libitum (AL) diet and the paternity of the offspring produced by multiply mated females was assigned using microsatellite markers. Compared to AL fish, RE females (i) had fewer mating partners, but the time interval between the first and the last mating was not affected; (ii) produced broods with a lower variance in male fertilization success (a measure of the opportunity for PCSS); and (iii) produced broods with a paternity bias towards the first mate (reversing the last sperm precedence observed in AL populations), and associated more towards males with higher courtship rate. Our results demonstrate that short‐term limitation in food availability significantly influence PCSS by modifying both fertilization success variance and sperm precedence pattern. Environmental variation should therefore become part of the research paradigm to improve our understanding of postcopulatory evolutionary dynamics. Read the free Plain Language Summary for this article on the Journal blog.

Female reproductive fluid concentrations affect sperm performance of alternative male phenotypes in an external fertilizer.

There is growing evidence that the female reproductive fluid (FRF) plays an important role in cryptic female choice through its differential effect on the performance of sperm from different males. In a natural spawning event, the male(s) may release ejaculate closer or further away from the spawning female. If the relative spatial proximity of competing males reflects the female pre-mating preference towards those males, then favoured males will encounter higher concentrations of FRF than unpreferred males. Despite this being a common situation in many external fertilizers, whether different concentrations of FRF can differentially influence the sperm performance of distinct male phenotypes (favoured and unfavoured by the female) remains to be elucidated. Here, we tested this hypothesis using the grass goby (Zosterisessor ophiocephalus), a fish with distinct territorial-sneaker reproductive tactics and female pre-mating preference towards territorial males, that consequently mate in an advantaged position and whose sperm experience higher concentrations of FRF. Our findings revealed a differential concentration-dependent effect of FRF over sneaker and territorial sperm motility only at low concentrations (i.e. at the distance where sneakers typically ejaculate), with increasing FRF concentrations (i.e. close to the eggs) similarly boosting the sperm performance of both sneaker and territorial males. The ability to release sperm close to the eggs is a prerogative of territorials, but FRF can likewise advantage the sperm of those sneakers that are able to get closer, allowing flexibility in the direction of female post-mating choice.

Population structure, mate choice, and genome transmission in naturally formed pairs in a Pelophylax lessonae–Pelophylax esculentus hybridogenetic system

Central European water frog Pelophylax esculentus is a hybrid that lives sympatrically and forms genetic systems with one of its parental species, in this case L-E (P. lessonae - P. esculentus). Hybrids are restored in each generation due to hybridogenesis, a unique mode of hemiclonal reproduction. We investigated changes in the species composition, mate choice, and genome transmission in naturally formed pairs in the L-E hybridogenetic system from the Raków fish pond complex (SW Poland). Our observations showed that the genetic system remained the same for over a decade but the share of the taxa and the sex ratios within the species changed. The frequency of P. lessonae decreased by about 20% in favor of P. esculentus. The proportion of males to females of P. lessonae increased twofold and of P. esculentus fourfold. We also found that the stability of the L-E population was ensured by a specific female mate choice pattern with the dominance of homotypic P. lessonae and heterotypic ♀P. esculentus × ♂P. lessonae pairs (almost 90% of the pairs collected from nature). The youngest females and males that formed a successful amplexus were 3 years old. We noted a male-male competition manifested by the exclusion of young males (before the third hibernation) from the participation in the mating. An analysis of genome transmission to gametes revealed that females P. lessonae transmitted Lx, while P. esculentus transmitted the Rx and/or Lx genomes. Males of P. lessonae transmitted the Lx or Ly genomes, while P. esculentus transmitted the Lx, Ly, and/or Rx genomes. The high proportion of the L genomes transferred to gametes enables both the restoration of the parental species P. lessonae and the regular renewal of a new generation of hybrids.Significance statementCentral European water frog complex includes two species: Pelophylax ridibundus (genotype RR) and P. lessonae (LL), and their natural hybrid, P. esculentus (RL). Hybrid individuals of both sexes reproduce due to a specific mode of reproduction, i.e., hybridogenesis, in which hybrids eliminate one of the parental genomes (R or L) from the germ line prior to meiosis and transmit the other one (not recombined, i.e., clonal) to the gametes. The hybrids live in mixed populations with one of the parental species and are restored in each generation. This, in turn, allows a kind of balance to be maintained in a population due to specific mate choice and genome transmission. Our research showed that the stability of the studied population was ensured by female preference to P. lessonae and male-male competition manifested by the exclusion of males under 3 years of age from the participation in the mating.