Females increase reproductive investment when mated to less sexually attractive males in a serially monogamous fish.

Reproductive investment decision is an integral part of life-history theory. Differential allocation hypothesis predicts that females should increase investment when mated to high-quality males, conversely, reproductive compensation hypothesis predicts that females should increase investment when mated to low-quality males. Empirical research dominantly focuses on polygamous species and rarely on serially monogamous species. So, the question remains: which hypothesis does serially monogamous species fit? And if it fits reproductive compensation hypothesis, do females only compensate once or continuously for multiple times when mating to low-quality males? Here, we used a serially monogamous fish, the lined seahorse (Hippocampus erectus), to investigate the reproductive investment pattern of females in relation to male quality (measured by sexual attractiveness). We found that females allocated more resources into eggs when they mated to less-sexually-attractive males, indicating the investment pattern of lined seahorse falls in with the prediction of reproductive compensation hypothesis. This finding may imply that the sex role of seahorses is reversed, and female is the side imposed on a greater sexual selection pressure. On this basis, we compared the investment difference of females in two consecutive breeding events when mated to less-sexually-attractive males. We found that females allocated less resources into eggs in the second breeding than in the first one. Females reduced their reproductive compensation in the second breeding, which may be attributed to the improvement in the quality (e.g., paternal care ability) of their mates after the first breeding, thus eliminating the need for them to invest more in the second breeding.

The effect of parental age on the quantity and quality of offspring in Syngnathus typhle, a species with male pregnancy.

Parental age impacts offspring quantity and quality. Most prior research focused on maternal age. Since in most organisms the mother produces the costly eggs plus provides all or most parental care, it is difficult to distinguish maternal effects mediated via the egg from later maternal care. Here, we addressed the effects of parental age on offspring in Syngnathus typhle, a pipefish with male pregnancy. The divide between one parent producing the eggs and the second parent being the exclusive provider of parental care facilitates a distinction between the effects of parental age on egg quality versus parental age on early development. We fully reciprocally crossed young and old mothers and young and old fathers and assessed impact of parental age combination on offspring number, offspring size, and offspring gene expression patterns. Neither parental combination significantly influenced offspring size or male gestation duration; however, they influenced the number of offspring. Paternal, but not maternal, age strongly affected the offspring gene expression. Offspring from old fathers exhibited substantial changes in the expression of genes related to cell cycle regulation, protein synthesis, DNA repair, and neurogenesis. Our findings thus highlight the importance of gestation, as opposed to gamete production, in shaping the parental contribution to offspring development.

A ghost moth olfactory prototype of the lepidopteran sex communication.

Sex role differentiation is a widespread phenomenon. Sex pheromones are often associated with sex roles and convey sex-specific information. In Lepidoptera, females release sex pheromones to attract males, which evolve sophisticated olfactory structures to relay pheromone signals. However, in some primitive moths, sex role differentiation becomes diverged. Here, we introduce the chromosome-level genome assembly from ancestral Himalaya ghost moths, revealing a unique olfactory evolution pattern and sex role parity among Lepidoptera. These olfactory structures of the ghost moths are characterized by a dense population of trichoid sensilla, both larger male and female antennal entry parts of brains, compared to the evolutionary later Lepidoptera. Furthermore, a unique tandem of 34 odorant receptor 19 homologs in Thitarodes xiaojinensis (TxiaOr19) has been identified, which presents overlapped motifs with pheromone receptors (PRs). Interestingly, the expanded TxiaOr19 was predicted to have unconventional tuning patterns compared to canonical PRs, with nonsexual dimorphic olfactory neuropils discovered, which contributes to the observed equal sex roles in Thitarodes adults. Additionally, transposable element activity bursts have provided traceable loci landscapes where parallel diversifications occurred between TxiaOr19 and PRs, indicating that the Or19 homolog expansions were diversified to PRs during evolution and thus established the classic sex roles in higher moths. This study elucidates an olfactory prototype of intermediate sex communication from Himalaya ghost moths.

The evolution of sex roles: The importance of ecology and social environment.

Males and females often have different roles in reproduction, although the origin of these differences has remained controversial. Explaining the enigmatic reversed sex roles where males sacrifice their mating potential and provide full parental care is a particularly long-standing challenge in evolutionary biology. While most studies focused on ecological factors as the drivers of sex roles, recent research highlights the significance of social factors such as the adult sex ratio. To disentangle these propositions, here, we investigate the additive and interactive effects of several ecological and social factors on sex role variation using shorebirds (sandpipers, plovers, and allies) as model organisms that provide the full spectrum of sex role variation including some of the best-known examples of sex-role reversal. Our results consistently show that social factors play a prominent role in driving sex roles. Importantly, we show that reversed sex roles are associated with both male-skewed adult sex ratios and high breeding densities. Furthermore, phylogenetic path analyses provide general support for sex ratios driving sex role variations rather than being a consequence of sex roles. Together, these important results open future research directions by showing that different mating opportunities of males and females play a major role in generating the evolutionary diversity of sex roles, mating system, and parental care.

Navigating sex and sex roles: deciphering sex-biased gene expression in a species with sex-role reversal (Syngnathus typhle).

Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in Syngnathus typhle, a sex-role reversed species with male pregnancy, allowing us to separate two female traits: egg production and parental care. Using RNA sequencing, we examined gene expression across organs (brain, head kidney and gonads) at various life stages, encompassing differences in age, sex and reproductive status. While some gene groups were more strongly associated with sex roles, such as stress resistance and immune defence, others were driven by biological sex, such as energy and lipid storage regulation in an organ- and age-specific manner. By investigating how genes regulate and are regulated by changing reproductive roles and resource allocation in a model system with an unconventional life-history strategy, we aim to better understand the importance of sex and sex role in regulating gene expression patterns, broadening the scope of this discussion to encompass a wide range of organisms.

Brood success of sex-role-reversed pheasant-tailed jacanas: the effects of social polyandry, seasonality, and male mating order.

Multiple mating by avian females may increase hatching and overall brood success; however, reproductive effort and parental investment are costly, and females may be gradually depleted, with lowered outputs over time. Thus, males in social polyandry systems may differ greatly in their reproductive gains. In the present study, we investigated the reproductive outputs of social polyandrous and sex-role-reversed pheasant-tailed jacanas, Hydrophasianus chirurgus, to assess the effects of polyandry, seasonality, and male mating order on breeding success. Female jacanas produced multiple clutches, either by leaving two or more clutches with an individual male (22%), or by mating with two or more males (78%). The polyandrous females laid both the first and second clutches earlier and showed a breeding period more than twice as long as that of monandrous females. Both polyandry and seasonality affected the fate of a clutch, where clutches from polyandrous females and the early season had higher hatching and brood success rates, but the number of polyandrous females declined over the season. Polyandrous females not only laid more clutches and eggs, and gained more hatchlings and fledglings, but also achieved higher per-clutch outputs and hatching rates than monandrous females. In polyandry groups, males gained higher total hatchlings and fledglings, although not total clutches or eggs, than males in monandry or bi-andry groups. Moreover, males in polyandry groups achieved higher hatchlings and fledglings per clutch and higher hatching and brood success rates. In polyandry groups, the first-mating males obtained more clutches, eggs, and hatchlings; however, they did not have higher success rates, nor total fledglings and per-clutch outputs, than males who mated later. Overall, the results indicate a selective advantage of polyandry for the jacanas studied, particularly in the early breeding season. This advantage, however, differs both between the sexes and intra-sexually, suggesting strong connections with certain ecological/environmental conditions in addition to the jacanas' own quality.

Mutual mate guarding with limited sexual conflict in a sex-role-reversed shorebird.

Mate guarding is typically considered a male strategy to protect paternity. However, under some circumstances, females might also benefit from guarding their mate. Female mate guarding might be particularly important in socially polyandrous species in which females compete for access to care-giving males. Because males also benefit from being near their partner to avoid paternity loss, pair members may have a mutual interest in mate guarding in polyandrous species. We studied the time spent together and movements that lead to separation, as behavioral measures of mate guarding, in the classically polyandrous red phalarope (Phalaropus fulicarius). We equipped 64 breeding pairs with miniaturized telemetry loggers with GPS to assess variation in mate-guarding intensity in relation to breeding phenology and season, nest attendance, and the occurrence of extrapair paternity. We show that red phalarope pairs were almost continuously together in the days before clutch initiation with no sex bias in separation movements, indicating mutual contribution to mate guarding. Our results suggest that in red phalaropes, both pair members guard their mate, with limited sexual conflict arising through biases in the operational sex ratio and a trade-off with male nest attendance. We found no clear relationship between mate-guarding intensity and the occurrence of extrapair paternity. In this non-territorial socially polyandrous species, mutual mate guarding might be the process underlying the evolution of a brief but strong social pair bond, with no other purpose than producing a clutch for a care-giving male.

Peer popularity and self-discipline as protective factors against depressive symptoms in Chinese adolescents: Do boys and girls benefit equally?

The current study examined the concurrent and longitudinal protective effects of peer popularity and self-discipline (control, planning, and the ability to prioritize important things) against depressive symptoms among adolescents. We used multilevel modeling to examine the data of 1676 adolescents aged 12-15 years from the China Family Panel Studies (CFPS) survey, a large-scale panel survey with a nationally representative sample. Results showed that both peer popularity and self-discipline predicted lower levels of depressive symptoms measured concurrently. The buffering effect of self-discipline against concurrent depressive symptoms was stronger for girls than for boys, especially in middle adolescence. Peer popularity additionally predicted lower levels of depressive symptoms 4 years later, and this effect was stronger for girls than for boys. These patterns of results were maintained after controlling for self-rated physical health and society-level factors. We discuss these findings against the background of distinct traditional gender roles.

Relationship between pelvic sensations and lifetime exposure to receptive anal intercourse among people with prostates.

BACKGROUND: Despite the negative stigma on receptive anal intercourse (RAI), this behavior has a positive influence on individuals' sexual and relationship health. No large studies have previously looked at specific sensations experienced during RAI and how these sensations may change with experience. AIM: In this study we aimed to quantify commonly reported pelvic sensations during RAI and determine whether their presentation changes with increasing experience of RAI. METHODS: An internet survey was conducted on sensations felt during RAI among people with prostates from July 2022-January 2023. The survey content was developed based on a mixed-methods qualitative study and inquired about demographic and sexual histories as well as sensations (pleasure, pain, urinary, and bowel) experienced during RAI. We used descriptive statistics to describe demographic and sexual histories. All data were stratified by lifetime exposure to RAI. OUTCOMES: The primary outcomes assessed included the quantification of both the primary sensations experienced during RAI and the associated bother. RESULTS: In total, 975 participants completed the survey. The median age was 32 (range 18-78) years. The average age of first participation in RAI was 21 ± 6.6 years. Most respondents were having sex at least once a week (65%). Nine percent of respondents reported fewer than 10 experiences with RAI, 26% reported 11-50 RAI experiences, 32% reported 51-200 experiences, 16% reported 201-500 experiences, and 18% reported >500 experiences. As the number of experiences with RAI increased (from <10 to >500 exposures), the reported frequency of pleasurable sensation increased from 41% to 92% (P < .0001), whereas severe insertional pain and symptoms of bowel urgency decreased from 39% to 13% and from 21% to 6%, respectively (P < .0001). Urinary urgency sensation did not differ by lifetime RAI experience. CLINICAL IMPLICATIONS: Lifetime RAI exposure can be readily assessed and correlates not only with pelvic sensation but also many other aspects of sexual health. These results imply that the etiology of dissatisfaction with pleasure or anodyspareunia during RAI may differ by lifetime RAI exposure. STRENGTHS AND LIMITATIONS: This is the first study to our knowledge to assess pelvic sensations experienced during RAI among a large sample of individuals. This is a cross-sectional study, and we cannot conclude how pelvic sensations change over time among individuals. Internet-based participants may not be representative of clinical populations. CONCLUSION: Lifetime exposure to RAI is positively associated with pleasure and is negatively associated with pain and bowel urgency. Pelvic sensations experienced during RAI appear to be dependent on lifetime RAI exposure history regardless of age.

The relationship between breastfeeding self-efficacy and gender roles in postpartum women.

Breastfeeding self-efficacy is important for the achievement and maintenance of breastfeeding. For this reason, it is important to investigate the physical, psychological, social, and cultural factors that may affect breastfeeding self-efficacy. This study sought to investigate how gender roles affect breastfeeding self-efficacy. The study had a descriptive, cross-sectional, and co-relational design and was conducted on 213 postpartum women. The data collection tools of the study were the "Demographic Data Collection Form," "BEM Gender Roles Inventory" and "Breastfeeding Self-Efficacy Scale Short Form." Percentages, means, and standard deviation served as the visual representation of descriptive statistics. The difference between the mean scores on the breastfeeding self-efficacy scale according to gender roles was investigated using one-way analysis of variance. In order to identify which measurement was the result of the difference, dependent groups underwent a t-test with Bonferroni correction. Among the women participating in the study, 39.9 percent had feminine, 35.2 percent androgynous, 14.1 percent masculine, and 10.8 percent ambiguous gender roles. It was concluded that women with androgynous gender roles have the highest level of breastfeeding self-efficacy in comparison other gender roles. Considering the inadequacy of education on breastfeeding or lack of counseling service providers for women's gender roles, there emerged a need for supportive care initiatives for the improvement of breastfeeding self-efficacy.

How Female-Female Competition Affects Male-Male Competition: Insights into Postcopulatory Sexual Selection from Socially Polyandrous Species.

AbstractSexual selection is a major driver of trait variation, and the intensity of male competition for mating opportunities has been linked with sperm size across diverse taxa. Mating competition among females may also shape the evolution of sperm traits, but the effect of the interplay between female-female competition and male-male competition on sperm morphology is not well understood. We evaluated variation in sperm morphology in two species with socially polyandrous mating systems, in which females compete to mate with multiple males. Northern jacanas (Jacana spinosa) and wattled jacanas (J. jacana) vary in their degree of social polyandry and sexual dimorphism, suggesting species differences in the intensity of sexual selection. We compared mean and variance in sperm head, midpiece, and tail length between species and breeding stages because these measures have been associated with the intensity of sperm competition. We found that the species with greater polyandry, northern jacana, has sperm with longer midpieces and tails as well as marginally lower intraejaculate variation in tail length. Intraejaculate variation was also significantly lower in copulating males than in incubating males, suggesting flexibility in sperm production as males cycle between breeding stages. Our results indicate that stronger female-female competition for mating opportunities may also shape more intense male-male competition by selecting for longer and less variable sperm traits. These findings extend frameworks developed in socially monogamous species to reveal that sperm competition may be an important evolutionary force layered atop female-female competition for mates.

Gender-associated role in patients with schizophrenia. Is there a connection with the resistance?

Schizophrenia is a chronic mental illness observed with equal prevalence in different cultures and ethnic groups. The clinical picture relates to behavior and social adaptation. A significant percentage of patients, despite the implementation of various therapeutic interventions, remain resistant to the ongoing treatment. Occupying a certain gender role depends both on biological belonging and on the way of self-perception characteristic of the given person. Self-perception reflects gender identification, which in social aspect is determined by the choice of social activities performed. Changes in behavior and social adaptation in patients with schizophrenia led us to conduct a study to analyze the perceived gender role in patients with schizophrenia, looking for differences between patients with treatment resistance and those in clinical remission. Materials and methods: A total of 105 patients with schizophrenia were analyzed. Of them, 45 were with resistant symptoms and 60 in clinical remission. The clinical analysis of the patients was carried out using the PANSS and BPRS scales. The evaluation of the choice of social activity related to a particular gender was done with the Bem Sex-Role Inventory (BSRI). Results: Out of all 105 patients with schizophrenia, in 80/76.19%/we found a higher identification with the female role, 17/16.19%/made an association with the male role and in 8/7.61%/patients we found the same results, i.e., with both the male and female roles. Among the patients with treatment resistant schizophrenia (TRS)-45, 34/75.56%/identified more with the female gender role, 6/13.33/perceived the male gender role as active, and in 5/11.11%/the identification was equal both with the male and with the female roles. Among the patients in clinical remission (CR)-60, 46/76.67%/accepted the female role as active, 11/18.33/identified with the male one, and three/5%/accepted both roles equally. When assessing the relationship between biological sex and perceived gender role, it was found that among men/a total of 39/half identified with the female gender role and half with the male gender role. Among women/a total of 66/, 90% perceived the female gender role, 7%-the male and 3% equally the male and the female gender role. No relationship was found between the choice of a certain gender role and the onset of psychosis and its duration in the observed patients. Conclusion: We found a higher percentage of schizophrenic patients who showed higher identification with the female gender role. Approximately half of the males identified with the female gender role. Resistance had no influence on the choice of sex-associated social activity. Factors related to the course of the schizophrenia process such as age of onset of psychosis and duration of psychosis was not associated with an influence on identification with sex-associated social activity. Our research suggests that identification with a particular sex associative social activity is most likely established earlier in the prodromal period.

Learning to anticipate mate presence shapes individual sex roles in the hermaphroditic pond snail, Lymnaea stagnalis.

Despite being simultaneously male and female, hermaphrodites may still need to assume the male or female sexual role in a mating encounter, with the option to swap roles afterwards. For the great pond snail, Lymnaea stagnalis, deciding which sexual role to perform has important consequences, since sperm transfer and male reproductive success can be decreased. We hypothesised that detecting cues that indicate a possible mating encounter could help them to adapt their mating behaviour. Therefore, we experimentally assessed whether signalling the presence of a conspecific with an odour can affect the sexual role of Lymnaea stagnalis. The results showed that learning resulted in either an increased ability to mate as a male or in faster mating compared to the control group. These findings reveal that learning shapes the mating dynamics of Lymnaea stagnalis, thus showing that cognitive processes not only affect mating in separate-sexed species but also in hermaphrodites.

Sex and gender associations with indicators of neurodevelopmental compromise in schizophrenia spectrum disorders.

BACKGROUND: It has been proposed that sex and gender differences described in schizophrenia can be explained from a neurodevelopmental perspective. AIM: In this study, we examined the associations of biological sex and gender role endorsement with putative indicators of neurodevelopmental compromise. METHODS: We used the Bem Sex Role Inventory to calculate masculinity scores in 77 patients with a first episode of a schizophrenia spectrum disorder, and selected the following indicators of neurodevelopmental compromise: family history of schizophrenia, obstetric complications, premorbid functioning, neurological soft signs, and cognitive function. Secondary objectives included the moderating effects of age of onset of illness, substance use and negative symptoms on these associations. RESULTS: There were no significant sex differences across any of the indicators of neurodevelopmental compromise. However, lower masculinity scores correlated significantly with poorer premorbid adjustment, sensory integration deficits and worse overall cognitive performance. Stepwise linear regression identified poorer premorbid adjustment in early adolescence and lower verbal learning scores as independent predictors of lower masculinity scores. In contrast to sex, gender showed several associations with indicators of neurodevelopmental compromise. CONCLUSIONS: Lower masculinity scores may represent part of a phenotype for a neurodevelopmental anomaly that places some individuals on a pathway to schizophrenia.

Incel Activity on Social Media Linked to Local Mating Ecology.

Young men with few prospects of attracting a mate have historically threatened the internal peace and stability of societies. In some contemporary societies, such involuntary celibate-or incel-men promote much online misogyny and perpetrate real-world violence. We tested the prediction that online incel activity arises via local real-world mating-market forces that affect relationship formation. From a database of 4 billion Twitter posts (2012-2018), we geolocated 321 million tweets to 582 commuting zones in the continental United States, of which 3,649 tweets used words peculiar to incels and 3,745 were about incels. We show that such tweets arise disproportionately within places where mating competition among men is likely to be high because of male-biased sex ratios, few single women, high income inequality, and small gender gaps in income. Our results suggest a role for social media in monitoring and mitigating factors that lead young men toward antisocial behavior in real-world societies.

Demography's theory and approach: (How) has the view from the margins changed?

Around the time that Population Studies celebrated its 50th anniversary in 1996, Susan Greenhalgh published 'An intellectual, institutional, and political history of twentieth-century demography'. Her contribution described a discipline that, when viewed from its margins, prompted scholars in other disciplines to ask the following questions: 'Why is the field still wedded to many of the assumptions of mid-century modernization theory and why are there no critical … perspectives in the discipline?' (Greenhalgh 1996, p. 27). Those questions still arise today. Similarly, Greenhalgh's observation that 'neither the global political economies of the 1970s, nor the postmodernisms and postcolonialities of the 1980s and 1990s, nor the feminisms of any decade have had much perceptible impact on the field' (pp. 27-8), remains a fairly accurate depiction of research published in Population Studies and other demography journals. In this contribution, focusing predominantly on feminist research and insights, I discuss how little has changed since 1996 and explain why the continued lack of engagement concerns me. Demographers still often fail to appreciate the impossibility of atheoretical 'just descriptive' research. Our methods carry assumptions and so rely on (often) implicit theoretical frameworks. Not making frameworks explicit does not mean they do not exert an important influence. I end by proposing that the training of research students should be part of a strategy to effect change.

Two sexes respond equally to food restriction in a sexually dimorphic but not body mass dimorphic jumping spider.

Natural selection favors animals that evolve developmental and behavioral responses that buffer the negative effects of food restrictions. These buffering responses vary both between species and within species. Many studies have shown sex-specific responses to environmental changes, usually in species with sexual size dimorphism (SSD), less found in species with weak or no SSD, which suggests that sizes of different sexes are experiencing different selections. However, previous studies usually investigated development and behavior separately, and the balanced situation where males and females of sexually dimorphic species respond in the same way to food restriction remains little known. Here, we investigated this in Phintelloides versicolor (Salticidae) that presents sexual dimorphism in color and shape but weak SSD. We examined whether food restriction induced the same responses in males and females in development duration, adult body size and weight, daily time allocated to foraging, and hunting. We found food restriction induced similar responses in both sexes: both exhibited longer development duration, smaller adult body size and weight, higher probability of staying outside nests and noticing prey immediately, and higher hunting success. However, there were sexual differences regardless of food condition: females showed faster development, smaller adult body size, higher probability of staying outside of nests, and higher hunting success. These indicated the differential selection on male and female sizes of P. versicolor could be under a balanced situation, where males and females show equal developmental and behavioral plasticity to environmental constraints.

Mate guarding in primates arises due to partner scarcity, even if the father provides no paternal care at all.

Paternal care is unusual among primates; in most species males compete with one another for the acquisition of mates and leave the raising of offspring to the mothers. Callitrichids defy this trend with both fathers and older siblings contributing to the care of offspring. We extend a two-strategy population model (paternal care versus male-male competition) to account for various mechanisms that could possibly explain why male callitrichids invest in paternal care over male-male competition, and compare results from callitrichid, chimpanzee and hunter-gatherer life history parameters. The survival benefit to offspring due to care is an insufficient explanation of callitrichid paternal care, and the additional inclusion of differences in lactation-related biology similarly do not change that picture. Instead, paternal care may arise in parallel with, or even as a result of, mate guarding, which in turn is only beneficial when partners are scarce as modelled by the birth sex ratio in callitrichids and menopause in hunter-gatherers. In that situation, care need not even provide any benefit to the young (in the form of a survival bonus) for guarding to out-compete multiple mating competition.

Evolution of nuptial gifts and its coevolutionary dynamics with male-like persistence traits of females for multiple mating.

BACKGROUND: Many male animals donate nutritive materials during courtship or mating to their female mates. Donation of large-sized gifts, though costly to prepare, can result in increased sperm transfer during mating and delayed remating of the females, resulting in higher paternity. Nuptial gifting sometimes causes severe female-female competition for obtaining gifts (i.e., sex-role reversal in mate competition) and selection on females to increase their mating rate, changing the intensity of sperm competition and the resultant paternity gains. We built a theoretical model to simulate such coevolutionary feedbacks between nuptial gift size (male trait) and propensity for multiple mating (female trait). Donation of nuptial gifts sometimes causes development of female persistence trait for gift acquisition. We also analyzed the causes and consequences of this type of traits, taking double receptacles for nutritious seminal gifts, which are known to occur in an insect group with a "female penis" (Neotrogla spp.), as an illustrative example. RESULTS: Our individual-based simulations demonstrated that female-female competition for male-derived nutrients always occur when the environment is oligotrophic and mating costs are low for females. However, a positive correlation between donated gift size and the resultant paternity gain was a requisite for the co-occurrence of large gifts and females' competitive multiple mating for the gifts. When gift donation satisfied female demands and thus resulted in monandry, exaggeration of nuptial gift size also occurred under the assumption that the last male monopolizes paternity. The evolution of double slots for gift acquisition and digestion (female persistence trait) always occurred when males could not satisfy the demands of females for gifts. However, through coevolutionary reduction in male gift size, fixation of this trait in a population drastically reduced the average female fitness. CONCLUSION: Sperm usage patterns, which have rarely been examined for animals with nuptial gifts, can be a critical factor for determining the extent of exaggeration in nuptial gifting. Sex-role reversals in mate competition, as a result of donation of nuptial gifts from males to females, can involve the evolution of male-like, persistent traits in females that reduce population productivity, as is the case with persistence traits in males.

Analysis of Sexual Inhibition and Satisfaction from a Gender Perspective among University Students.

University is characterized by a critical stage where students experience their sexuality, across a range of relationships. From these experiences, university students consolidate their personality and their sexual role. Factors such as age, sex, or traumatic experiences of violence or sexual abuse can affect their sexual role. The present study aims to analyze how the variables age, sex and having suffered abuse or violence may predict sexual satisfaction and inhibition. In addition, we analyze the mediating effect that sexual role plays on these relationships. For this purpose, Bem Sex Role Inventory (BSRI-12), Sociosexual Orientation Inventory (SOI-R), Inhibited Sexual Desire Test (ISD) and New Sexual Satisfaction Scale (NESS) were administered to 403 university students. The findings report that sex (ß = -0.313), age (ß = -0.116) and being a survivor of sexual assault (ß = 0.413) are predictive of male role, but not from the female role. Also, people with more male features tend to have lower levels of commitment and inhibition than those who have more female ones.