Female Choice Research Articles

Causes and consequences of variation in development time in a field cricket.

Variation in development time can affect life-history traits that contribute to fitness. In Gryllus vocalis, a non-diapausing cricket with variable development time, we used a path analysis approach to determine the causative relationships between parental age, offspring development time and offspring life-history traits. Our best-supported path model included both the effects of parental age and offspring development time on offspring morphological traits. This result suggests that offspring traits are influenced by both variation in acquisition of resources and trade-offs between traits. We found that crickets with longer development times became larger adults with better phenoloxidase-based immunity. This is consistent with the hypothesis that crickets must make a trade-off between developing quickly to avoid predation before reproduction and attaining better immunity and a larger adult body size that provides advantages in male-male competition, mate choice and female fecundity. Slower-developing crickets were also more likely to be short-winged (unable to disperse by flight). Parental age has opposing direct and indirect effects on the body size of daughters, but when both the direct and indirect effects of parental age are taken into account, younger parents had smaller sons and daughters. This pattern may be attributable to a parental trade-off between the number and size of eggs produced with younger parents producing more eggs with fewer resources per egg. The relationships between variables in the life-history traits of sons and daughters were similar, suggesting that parental age and development time had similar causative effects on male and female life-history traits.

Genomic Signatures of Sexual Selection on Pollen-Expressed Genes in Arabis alpina.

Fertilization in angiosperms involves the germination of pollen on the stigma, followed by the extrusion of a pollen tube that elongates through the style and delivers two sperm cells to the embryo sac. Sexual selection could occur throughout this process when male gametophytes compete for fertilization. The strength of sexual selection during pollen competition should be affected by the number of genotypes deposited on the stigma. As increased self-fertilization reduces the number of mating partners, and the genetic diversity and heterozygosity of populations, it should thereby reduce the intensity of sexual selection during pollen competition. Despite the prevalence of mating system shifts, few studies have directly compared the molecular signatures of sexual selection during pollen competition in populations with different mating systems. Here we analyzed whole-genome sequences from natural populations of Arabis alpina, a species showing mating system variation across its distribution, to test whether shifts from cross- to self-fertilization result in molecular signatures consistent with sexual selection on genes involved in pollen competition. We found evidence for efficient purifying selection on genes expressed in vegetative pollen, and overall weaker selection on sperm-expressed genes. This pattern was robust when controlling for gene expression level and specificity. In agreement with the expectation that sexual selection intensifies under cross-fertilization, we found that the efficacy of purifying selection on male gametophyte-expressed genes was significantly stronger in genetically more diverse and outbred populations. Our results show that intra-sexual competition shapes the evolution of pollen-expressed genes, and that its strength fades with increasing self-fertilization rates.

Thiamethoxam as an inadvertent anti-aphrodisiac in male bees

Sexual reproduction is common to almost all multi-cellular organisms and can be compromised by environmental pollution, thereby affecting entire populations. Even though there is consensus that neonicotinoid insecticides can impact non-target animal fertility, their possible impact on male mating success is currently unknown in bees. Here, we show that sublethal exposure to a neonicotinoid significantly reduces both mating success and sperm traits of male bumblebees. Sexually mature male Bombus terrestris exposed to a field-realistic concentration of thiamethoxam (20 ng g−1) or not (controls) were mated with virgin gynes in the laboratory. The results confirm sublethal negative effects of thiamethoxam on sperm quantity and viability. While the latency to mate was reduced, mating success was significantly impaired in thiamethoxam-exposed males by 32% probably due to female choice. Gynes mated by exposed males revealed impaired sperm traits compared to their respective controls, which may lead to severe constraints for colony fitness. Our laboratory findings demonstrate for the first time that neonicotinoid insecticides can negatively affect male mating success in bees. Given that holds true for the field, this provides a plausible mechanism contributing to declines of wild bee populations globally. The widespread prophylactic use of neonicotinoids may therefore have previously overlooked inadvertent anti-aphrodisiac effects on non-target animals, thereby limiting conservation efforts.

Perceived Mate Scarcity Leads to Increased Willingness to Mate Poach

ABSTRACT Mate poaching, where an individual attempts to attract a pair-bonded individual, is a risky mating tactic. Yet, it is surprisingly common. Although many studies have investigated individual differences in mate poaching, few have examined potentially relevant ecological factors, such as mate availability. In this study, 254 unmated North American adults were primed with either perceived mate scarcity or abundance, and subsequently completed measures of fear of being single, intrasexual competitiveness, and attitudes toward mate poaching. Results from a sequential mediation model revealed that men and women primed with mate scarcity held a more positive attitude toward mate poaching relative to those primed with mate abundance, and that this link was mediated by an induced fear of being single and intrasexual competitiveness. Our results suggest that mate poaching is a facultative adaptation of human mating psychology driven by intrasexual competitiveness that is activated in response to environments of low mate availability. It highlights the need for researchers to consider ecological cues when studying individual variation in mate poaching behavior.

Male coloration affects female gestation period and timing of fertilization in the guppy (Poecilia reticulata)

The trade-up hypothesis is a female behavioral strategy related to mating with multiple males. In this hypothesis, females can produce high-quality offspring while avoiding the risk of losing reproductive opportunities by non-selective mating with males at first mating and then re-mating with more attractive males. As an internal mechanism to realize this behavioral strategy, we predicted that females would immediately fertilize their eggs when they mated with attractive males, whereas females would delay fertilization when they mated with unattractive males to trade-up sires of offspring. The guppy (Poecilia reticulata) is an ovoviviparous fish with internal fertilization, and females show a clear mate preference based on the area of orange coloration on the bodies of males. In addition, it is known that females show a re-mating strategy consistent with the trade-up hypothesis. We tested whether the attractiveness of mated males affected the gestation period and the timing of fertilization. Females were paired with either colorful males or drab males, and the gestation periods (the number of days from mating to parturition) were compared. In addition, we dissected the abdomens of the females at intervals of several days after mating and observed whether the eggs were fertilized. The gestation period in females that were paired with attractive colorful males was significantly shorter than that in females that were paired with drab males. We found that females that mated with colorful males also had their eggs fertilized earlier than those that mated with drab males. Our findings show that differences in the timing of fertilization according to attractiveness of the mate increase the opportunity for cryptic female choice and trading up.

Consort partner preference in male Tibetan macaques: How to choose when females conceal their ovulation?

Growing evidence suggested that males suffer energetic costs from sexual behavior, males should discriminate among receptive females due to their reproductive quality, and deservedly, they would prefer females during the fertile phase. However, in species with females concealing their ovulation, males cannot identify the females’ fertile phase, and then what are the criteria for males to select their female partners? To answer this question, we collected behavioral data spanning two consecutive years (from February 2017 to January 2019) to investigate the effects of female individual, social and sexual traits on male consort partner choice in Tibetan macaques ( Macaca thibetana ), a species characterized by distinct seasonal breeding and female concealed ovulation, at Mt. Huangshan, China. Results showed that, in terms of individual traits, males prefer to consort with young/middle-aged, but not old or high-fecundity females; in terms of social traits, males did not engage in more consortship with high-ranking females or their previous non-sexual “friends”; in terms of sexual traits, males were more likely to consort with lower-polyandry females (the level of diversity of the female sexual solicitation). Besides, our results also showed that, compared to other males, alpha males consort more with higher-ranking and lower-polyandry females. Our study suggested that males selected their consort partner based on female sexual traits rather than individual and social traits. Contrary to the previous insights of sexual selection that emphasized female choice and male-male competition, the current study focused on male consort partner choice to provide new insights into the co-evolution of female concealed ovulation and male mating decisions.

Postpartum contraceptive practices among urban and peri-urban women in North India: a mixed-methods cohort study protocol

BackgroundPostpartum family planning (PPFP) helps women space childbirths, increase exclusive breastfeeding and prevent unintended pregnancies, leading to reduction in maternal, infant and child morbidities and mortality. Unmet need of family planning is highest among women in the postpartum period due to lack of knowledge, cultural and religious barriers, access barriers and low antenatal care service utilization. However, in spite of low prevalence of postpartum family planning practices, birth-to-birth interval is reportedly high in Delhi, India. This study explores the postpartum contraception practices and the relationship between use of postpartum contraception and subsequent child linear growth.MethodsThis is a mixed method cohort study on PPFP and is nested within an ongoing “Women and Infants Integrated Interventions for Growth Study” (WINGS). Married women aged 18–30 years who have delivered a live baby are recruited for quantitative interviews at 6 weeks, 6, 12, and 24 months postpartum. In-depth interviews are conducted with a randomly selected sub-sample of women at each of the four time points, 35 husbands and 20 local service providers to understand their perspectives on PPFP practices.DiscussionThe findings from the study will provide useful insights into couples’ contraception preferences and choice of contraception, modern and traditional, initiation time and the effect of birth spacing and contraception use on subsequent linear growth of the child. This knowledge will be of significant public health relevance and will help in designing appropriate interventions for appropriate postpartum contraception use and delivery strategies. The study aims to work address the Sexual and Reproductive Health and Rights goal of promoting reproductive health, voluntary and safe sexual and reproductive choices for women.Trial registrationTrial registration number: CTRI/2020/03/023954.

An intergenerational androgenic mechanism of female intrasexual competition in the cooperatively breeding meerkat

Female intrasexual competition can be intense in cooperatively breeding species, with some dominant breeders (matriarchs) limiting reproduction in subordinates via aggression, eviction or infanticide. In males, such tendencies bidirectionally link to testosterone, but in females, there has been little systematic investigation of androgen-mediated behaviour within and across generations. In 22 clans of wild meerkats (Suricata suricatta), we show that matriarchs 1) express peak androgen concentrations during late gestation, 2) when displaying peak feeding competition, dominance behaviour, and evictions, and 3) relative to subordinates, produce offspring that are more aggressive in early development. Late-gestation antiandrogen treatment of matriarchs 4) specifically reduces dominance behaviour, is associated with infrequent evictions, decreases social centrality within the clan, 5) increases aggression in cohabiting subordinate dams, and 6) reduces offspring aggression. These effects implicate androgen-mediated aggression in the operation of female sexual selection, and intergenerational transmission of masculinised phenotypes in the evolution of meerkat cooperative breeding.

Sex role similarity and sexual selection predict male and female song elaboration and dimorphism in fairy-wrens.

Historically, bird song complexity was thought to evolve primarily through sexual selection on males; yet, in many species, both sexes sing and selection pressure on both sexes may be broader. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high, temperate latitudes. Furthermore, we expect male–female song structure and elaboration to be more similar at lower, tropical latitudes, where longer breeding seasons and year‐round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both types of selective pressures and sexes into account. We examined song in both sexes in 15 populations of nine‐fairy‐wren species (Maluridae), a Southern Hemisphere clade with female song. We compared song elaboration (in both sexes) and sexual song dimorphism to latitude and life‐history variables tied to sexual and social selection pressures and sex roles. Our results suggest that song elaboration evolved in part due to sexual competition in males: male songs were longer than female songs in populations with low male survival and less male provisioning. Also, female songs evolved independently of male songs: female songs were slower paced than male songs, although only in less synchronously breeding populations. We also found male and female songs were more similar when parental care was more equal and when male survival was high, which provides strong evidence that sex role similarity correlates with male–female song similarity. Contrary to Northern Hemisphere latitudinal patterns, male and female songs were more similar at higher, temperate latitudes. These results suggest that selection on song can be sex specific, with male song elaboration favored in contexts with stronger sexual selection. At the same time, selection pressures associated with sex role similarity appear to favor sex role similarity in song structure.

Latitudinal gradients in sexual dimorphism: Alternative hypotheses for variation in male traits.

Biological patterns across latitudinal gradients elucidate a number of striking natural clines from which numerous processes can be further explored. The trade‐off between reproduction and somatic maintenance and growth represents a suite of life‐history traits with variable energy allocation and potential latitudinal patterns. Specifically, male sexually dimorphic traits in female choice systems represent one such reproductive investment constrained by resource acquisition and subsequent allocation. Latitudinal variation in sexual dimorphism has been suggested although the relationship between dimorphic traits and latitude are conflicting. Here, we test alternative hypotheses regarding this pattern using two broadly distributed vertebrates exhibiting sexually dimorphic traits. We hypothesized that the exaggeration of dimorphic traits correlates with latitude, with males having exaggerated sexually dimorphic traits at either higher or lower latitudes. Results indicate that male sexually dimorphic traits are exaggerated at lower latitudes while relative gonopodium size in Poecilia latipinna was larger at higher latitudes. This pattern may be a result of lower latitude populations experiencing greater population densities and longer access to resources that could manifest in females more intensively selecting for higher quality males in lower latitudes. Experimental work should address this pattern and investigate mechanistic processes.

Carcass Scavenging Relaxes Chemical-Driven Female Interference Competition in Flour Beetles

AbstractFemale-female nonsexual interference competition is a major fitness determinant of biased sex ratio groups with high female density. What strategies can females use to overcome the negative impact of this competition? To answer this question we used flour beetles (Tribolium castaneum) where competing females from female-biased groups were already known to suppress each other's fecundity by secreting toxic quinones from their stink glands, indicating a unique chemical-driven interference competition. Surprisingly, increasing resources did not alleviate these fitness costs. Females also did not disperse more from the site of interference competition. Hence, the competition was influenced by neither the total resource availability nor the lack of opportunity to avoid chemical interference. Instead, protein sequestered via scavenging of nutrient-rich carcasses relaxed female competition by increasing fecundity and reducing the quinone content. Finally, stink gland components themselves triggered carcass scavenging and increased fecundity, indicating the possibility of a novel chemical-driven feedback loop to reduce the competition. In the present work we provide the rare analyses where multiple competing hypotheses were jointly tested to establish carcass scavenging as an important potential strategy to overcome the fitness costs of intrasexual female interference competition.

Sexual and reproductive health knowledge, sexual attitudes, and sexual behaviour of university students: Findings of a Beijing-Based Survey in 2010-2011

BackgroundAlthough several studies have attempted investigating sex-related knowledge, attitudes, and practices among young people in China, deeper insights were still needed to further understand how this population could be supported to make healthy and safe sexual choices. Against this background, this study used a large set of secondary data to examine associations among sexual and reproductive health (SRH) knowledge, sexual attitudes, and sexual behaviour.MethodsA cross-sectional study was employed to explore the associations among SRH knowledge, sexual attitudes, and sexual behaviour with a publicly available survey data among the 1196 university students from freshmen to Ph.D. candidates. Descriptive analysis was used to describe the sociodemographic characteristics of the university students by gender. Associations of sociodemographic factors with sources and categories of SRH knowledge, categories of contraceptive knowledge, sexual attitudes, and sexual behavior were explored with Poisson regressions and logistic regressions, respectively. The mediating effects of sociodemographic factors on the associations between SRH knowledge and sexual behavior, observed sexual attitudes on the associations of SRH knowledge with sexual behavior, and latent sexual attitudes on the relationship between SRH knowledge and sexual behavior were analyzed in order.ResultsDescriptive analysis showed that the sample was dominated by age group (18 to 24 years), undergraduates, females, limited contraceptive knowledge, unfavorable sexual attitudes, and insufficient knowledge sources. Regression analyses showed that sociodemographic factors had significant associations with SRH knowledge, sexual attitudes, and sexual behavior. Subsequently, the mediating effects of sociodemographic factors on the associations of SRH knowledge and sexual attitudes with sexual behavior were confirmed. Controlling for sociodemographic factors, the effects of sexual attitudes on the associations between SRH knowledge and sexual behaviour could be verified. Structural equation modeling indicated that the linear sequence of sources and categories of SRH knowledge → sexual attitudes → sexual behaviour model and the triangle mediating effects of sexual behaviour → sexual attitudes → SRH knowledge model existed.ConclusionsSociodemographic factors and observed sexual attitudes mediated the associations between SRH knowledge and sexual behaviour. The sequence relationship: sources and categories of SRH knowledge → sexual attitudes → sexual behavior and the mediating relationship: sexual behavior → sexual attitude → sources and categories of SRH knowledge & sexual behavior → sources and categories of SRH knowledge and sexual behavior → sexual attitude → categories of contraceptive knowledge & sexual behavior → categories of contraceptive knowledge were confirmed in the sample. This study also identified an urgent need for the university students to access to SRH comprehensive knowledge.

Seasonality drives variation in the use of forest strata by adult males of a dimorphic frugivorous bird species

AbstractAnimals may exploit habitat complexity in a myriad of ways, and a widespread pattern of habitat use is vertical stratification. In tropical forests, it often increases niche diversity for frugivorous birds, and it strongly influences seed dispersal and community persistence. Yet, most studies disregard intraspecific variations in the use of forest layers and their ecological and evolutionary consequences. In this study, we asked whether adult males and green individuals (females and juveniles) of a dimorphic frugivorous bird, the helmeted manakin (Antilophia galeata, Pipridae) foraged at different strata in a forest from Southeastern Brazil. We also investigated how the seasonal dynamics of fruit availability and distribution within the forest affect between‐ and within‐phenotype use of forest layers. We conducted field observations of the foraging activity of both phenotypes and found that they were mainly midstory foragers flying at similar heights in both seasons. However, adult males increased their stratum breadth and their foraging height during the wet season, when fruits were also available at higher strata, while the foraging behaviour of green individuals remained seasonally invariant. The different effects of seasonality on the phenotypes of the helmeted manakin may be a consequence of sexual competition among adult males in the wet season to secure fruits in taller plants. Altogether, our findings show that seasonality affects differently the spatial use behaviours of males and green individuals, and understanding these intraspecific differences may help us predict how species respond to environmental disturbances affecting habitat structure and frugivores assemblages.

Life history, mating dynamics and the origin of parental care.

Parental care, mating dynamics and life history co-evolve. Understanding the diversity of reproductive patterns found in nature is a major focus of evolutionary ecology research. Previous research suggests that the origin of parental care of eggs will be favoured when egg and adult death rates and juvenile survival are relatively high. However, the previous research that explored the link between care and life history did not account for among-species variation in mating dynamics. As mating dynamics are generally expected to influence care, we explore, theoretically, the life-history conditions (stage-specific rates of maturation and survival) that favour parental care across three mating scenarios: reproductive rate (1) is unaffected by males (assuming that some males are present), (2) increases as male abundance increases or (3) decreases as male abundance increases. Across scenarios, all forms of care were most strongly favoured when egg and adult death rates, juvenile survival and female egg maturation rates were relatively high. When reproductive rate was unaffected by male abundance or increased as male abundance increased, as we might expect in systems in which females are mate-limited, all forms of care were most strongly favoured when male egg maturation rate (i.e. the rate at which male eggs develop, mature and hatch) was moderate or high. When greater male abundance inhibited reproduction, which might occur in systems with intense male-male competition, all forms of care were most strongly favoured when male egg maturation rate was low-to-moderate. These results suggest that life history affects the evolution of parental care, and sex-specific life history can interact with mating dynamics to influence the origin of care.

Dual function and associated costs of a highly exaggerated trait in a cichlid fish.

Exaggerated secondary sexual characteristics are apparently costly and seem to defy natural selection. This conundrum promoted the theory of sexual selection. Accordingly, exaggerated secondary sexual characteristics might be ornaments on which female choice is based and/or armaments used during male–male competition. Males of many cichlid fish species, including the adaptive radiation of Nicaraguan Midas cichlids, develop a highly exaggerated nuchal hump, which is thought to be a sexually selected trait. To test this hypothesis, we conducted a series of behavioral assays in F2 hybrids obtained from crossing a species with a relatively small hump and one with an exaggerated hump. Mate‐choice experiments showed a clear female preference for males with large humps. In an open‐choice experiment with limited territories, couples including large humped males were more successful in acquiring these territories. Therefore, nuchal humps appear to serve dual functions as an ornament for attracting mates and as an armament for direct contest with rivals. Although being beneficial in terms of sexual selection, this trait also imposes fitness costs on males possessing disproportionally large nuchal humps since they exhibit decreased endurance and increased energetic costs when swimming. We conclude that these costs illustrate trade‐offs associated with large hump size between sexual and natural selection, which causes the latter to limit further exaggeration of this spectacular male trait.

Achieving Status and Reducing Loneliness during the Transition to College: The Role of Entitlement, Intrasexual Competitiveness, and Dominance.

Although many emerging adults struggle to gain status and develop social relationships, particularly during the college transition, it remains unclear whether certain personality traits facilitate this transition. Using a longitudinal design, we investigated whether status-related traits-namely, entitlement, intrasexual competitiveness, and dominance-related to the development of status in 91 first-year college students (M age=18.15, SD=0.44) transitioning to a novel college environment. We also examined whether personality traits moderated the degree to which status related to loneliness. As hypothesized, only students high in intrasexual competitiveness experienced increases in subjective dorm status across the year. In addition, students exhibiting average or low entitlement experienced decreases in loneliness over time, whereas high entitlement was related to consistently low loneliness. Finally, higher subjective dorm status was related to lower loneliness only for less dominant students, as assessed by both self-ratings of trait dominance and raters' judgments of facial dominance from photographs. Using a real-world context of status development, these results suggest that personality traits may influence students' ability to experience higher status and modulate the relation between subjective status and loneliness.

Let's talk about sex roles: what affects perceptions of sex differences in animal behaviour?

In the field of sexual selection, it is common to encounter the idea of ‘sex roles’: choosy and caring females and competitive and promiscuous males. Despite criticism of these stereotypes from some evolutionary biologists, sex roles still appear as a norm in much of the sexual selection-related literature. This may be because scientists anthropomorphize animal behaviours, which raises the question of whether demographic traits and experiences can influence one's perception regarding sex differences in nature. Here we tested whether age, gender, country and experiences are associated with different perceptions of sex differences in nature. We conducted a survey in which we asked participants about their perception of the frequency at which certain behaviours associated with sex roles (promiscuity, mate choice, intrasexual competition and parental care) occur in nonhuman animals for each sex. We found that participants' country, research experience with certain taxonomic groups and research experience with sex-specific topics were associated with different perceptions of sex differences in nonhuman animals; participants from more gender-unequal countries showed greater agreement with the idea of sex roles. In contrast, participants who had experience with mechanisms not predicted by the idea of sex roles such as male mate choice, paternal care and female–female competition showed lower agreement with the idea of sex roles than other participants. We suggest that increasing social diversity in academia and encouraging researchers to diversify the sexes and taxa of animals they use to investigate reproductive behaviours could challenge pre-existing biases in animal sex differences. • The idea of sex roles represents a stereotypical view of females and males. • Researchers' perceptions of sex differences in nature are diverse. • Agreement with the idea of sex roles can depend on research experience. • Drawing broad conclusions based on current data can be misleading.

Effects of Gender Role Beliefs on Social Connectivity and Marital Safety: Findings From a Cross-Sectional Study Among Married Adolescent Girls in India

PurposeThe purpose of the study was to examine associations of gender role beliefs with marital safety as well as social and digital connectivity among married adolescent girls in India. MethodsWe analyzed cross-sectional survey data from married adolescent girls from rural Bihar and Uttar Pradesh, India in 2015–2016 (N = 4,893). Gender role belief items assessed participants' beliefs regarding appropriateness of female marital choice and economic decision-making, male childcare responsibility, and marital violence. The outcomes were time with friends (social connection), freedom of movement, mobile phone ownership and internet access (digital connection), and safety from marital violence (marital safety). Adjusted regression models examined associations between gender role beliefs and outcomes, caste/religion beliefs related to segregation, and demographics. ResultsBeliefs supportive of female marital choice (adjusted odds ratio [AOR] 1.38, 95% confidence interval [CI] 1.00–1.88, p = .048) and female economic decision-making (AOR 1.43, 95% CI 1.03–1.99, p = .03) were associated with social connection. Beliefs supportive of female marital choice (AOR 1.88, 95% CI 1.31–2.71, p = .001), female economic decision-making (AOR 1.67, 95% CI 1.03–2.72, p = .04), and male childcare responsibilities (AOR 1.42, 95% CI 1.05–1.94, p = .03) were associated with freedom of movement. Belief supporting female marital choice was associated with mobile phone ownership (AOR 1.23, 95% CI 1.01–1.50, p = .04), and belief supporting male childcare responsibility was associated with internet access (AOR 1.76, 95% CI 1.11–2.77, p = .02). Beliefs supportive of female marital choice (AOR .73, 95% CI .59–.89, p = .003), male childcare responsibility (AOR 1.26, 95% CI 1.03–1.54, p = .02), and unacceptability of marital violence (AOR 1.72, 95% CI 1.38–2.15, p < .001) were associated with safety from marital violence. ConclusionsProgressive gender role beliefs regarding female choice, control, and safety in marriage are associated with greater connectivity and safety for married adolescent girls in India. Future studies that can longitudinally assess these associations are warranted.

Mate Choice, Sex Roles and Sexual Cognition: Neuronal Prerequisites Supporting Cognitive Mate Choice

Across taxa, mate choice is a highly selective process involving both intra- and intersexual selection processes aiming to pass on one’s genes, making mate choice a pivotal tool of sexual selection. Individuals adapt mate choice behavior dynamically in response to environmental and social changes. These changes are perceived sensorily and integrated on a neuronal level, which ultimately leads to an adequate behavioral response. Along with perception and prior to an appropriate behavioral response, the choosing sex has (1) to recognize and discriminate between the prospective mates and (2) to be able to assess and compare their performance in order to make an informed decision. To do so, cognitive processes allow for the simultaneous processing of multiple information from the (in-) animate environment as well as from a variety of both sexual and social (but non-sexual) conspecific cues. Although many behavioral aspects of cognition on one side and of mate choice displays on the other are well understood, the interplay of neuronal mechanisms governing both determinants, i.e., governing cognitive mate choice have been described only vaguely. This review aimed to throw a spotlight on neuronal prerequisites, networks and processes supporting the interaction between mate choice, sex roles and sexual cognition, hence, supporting cognitive mate choice. How does neuronal activity differ between males and females regarding social cognition? Does sex or the respective sex role within the prevailing mating system mirror at a neuronal level? How does cognitive competence affect mate choice? Conversely, how does mate choice affect the cognitive abilities of both sexes? Benefitting from studies using different neuroanatomical techniques such as neuronal activity markers, differential coexpression or candidate gene analyses, modulatory effects of neurotransmitters and hormones, or imaging techniques such as fMRI, there is ample evidence pointing to a reflection of sex and the respective sex role at the neuronal level, at least in individual brain regions. Moreover, this review aims to summarize evidence for cognitive abilities influencing mate choice and vice versa. At the same time, new questions arise centering the complex relationship between neurobiology, cognition and mate choice, which we will perhaps be able to answer with new experimental techniques.

Does sexual experience affect the strength of male mate choice for high-quality females in Drosophila melanogaster?

Although females are traditionally thought of as the choosy sex, there is increasing evidence in many species that males will preferentially court or mate with certain females over others when given a choice. In the fruit fly, Drosophila melanogaster, males discriminate between potential mating partners based on a number of female traits, including species, mating history, age, and condition. Interestingly, many of these male preferences are affected by the male's previous sexual experiences, such that males increase courtship toward types of females that they have previously mated with and decrease courtship toward types of females that have previously rejected them. D. melanogaster males also show courtship and mating preferences for larger females over smaller females, likely because larger females have higher fecundity. It is unknown, however, whether this preference shows behavioral plasticity based on the male's sexual history as we see for other male preferences. Here, we manipulate the sexual experience of D. melanogaster males and test whether this manipulation has any effect on the strength of male mate choice for large females. We find that sexually inexperienced males have a robust courtship preference for large females that is unaffected by previous experience mating with, or being rejected by, females of differing sizes. Given that female body size is one of the most common targets of male mate choice across insect species, our experiments with D. melanogaster may provide insight into how these preferences develop and evolve.