Sexual selection and life history interact to influence the evolution of paternal care.

Parental care is essential to offspring survival in many species. Understanding why males of some species provide care, whereas others do not, has received substantial attention. Previous research has found that sexual selection can favor paternal care, yet we still do not fully understand why sexual selection favors male care in some species but not others. It is also unclear when paternal care versus other preferred male trait(s) will be favored by sexual selection. We hypothesize that sexual selection can interact with basic life history to influence the conditions under which paternal care and/or another preferred male trait will be favored by sexual selection. We used a mathematical approach in which males alone provide parental care and exhibit a non-care trait that is preferred in mate choice. Using this approach, we demonstrate that life-history characteristics (stage-specific mortality, fertilization success, gamete numbers) can interact with sexual selection to influence the evolution of paternal care and/or a preferred non-care trait. In particular, whether (1) adult mortality, egg mortality, and fertilization success are high versus low and (2) a tradeoff exists between paternal care and a non-care preferred trait will influence whether selection most strongly favors additional paternal care or a non-care preferred trait. In general, we would expect strong selection for more male care when it is preferred in mate choice. In some cases, mate preferences for paternal care can inhibit selection for a preferred non-care trait. Mate preferences for paternal care can also broaden the life-history conditions under which we would expect the elaboration of male care to occur.

Evolutionary drivers of sex-specific parasite prevalence in wild birds.

Males and females often differ in ecology, behaviour and lifestyle, and these differences are expected to lead to sex differences in parasite susceptibility. However, neither the sex differences in parasite prevalence, nor their ecological and evolutionary drivers have been investigated across a broad range of taxa using phylogenetically corrected analyses. Using the most extensive dataset yet that includes 755 prevalence estimates from 151 wild bird species in a meta-analytic framework, here we compare sex differences in blood and gastrointestinal parasites. We show that despite sex differences in parasite infection being frequently reported in the literature, only Haemoproteus infections were more prevalent in females than in males. Notably, only seasonality was strongly associated with the sex-specific parasite prevalence of both Leucocytozoon and Haemoproteus, where birds showed greater female bias in prevalence during breeding periods compared to the non-breeding period. No other ecological or sexual selection variables were associated with sex-specific prevalence of parasite prevalence. We suggest that much of the variation in sex-biased prevalence could be idiosyncratic, and driven by local ecology and behavioural differences of the parasite and the host. Therefore, breeding ecology and sexual selection may only have a modest influence on sex-different parasite prevalence across wild birds.

Strength of Sexual Selection and Sex Roles Vary between Social Groups in a Coral Reef Cardinalfish.

AbstractThe strength and direction of sexual selection can vary among populations. However, spatial variability is rarely explored at the level of the social group. Here we investigate sexual selection and sex roles in the paternally mouthbrooding, socially monogamous, and site-attached pajama cardinalfish, Sphaeramia nematoptera. Females were larger and more aggressive and had a longer dorsal fin filament, indicating reversed sex roles. At the scale of social groups, we show that the Bateman gradient and reproductive variance depend on the sex ratio and size of groups. In small and medium-sized groups with balanced or male-biased sex ratios, Bateman gradients were steeper for females, whereas gradients were equally steep for both sexes in large groups or when the sex ratio was female biased. For both sexes, reproductive variance increased with group size and with a higher male-to-female sex ratio. In S. nematoptera, mating opportunities outside the socially monogamous pair appear to impact sexual selection. We conclude that strength and direction of sexual selection can be masked by social dynamics in group-living species when considering only population and large-scale demographic processes.

Gender Roles and Mobile Dating Applications: Exploring Links Between User Characteristics and Traditional Gender Expressions in Self-Presentations.

This linkage study examined the prevalence of traditional gender expressions in the textual and visual profile cues on mobile dating applications (MDA) (nbiographies = 396, npictures = 1352) of 396 young adults' (Mage = 22.39 years, SD = 2.86, 73% women) with attention to users' gender, sexual orientation, and platform type. For 184 users (Mage = 22.10 years, SD = 2.91, 75% women) media content data were linked to self-report survey data. Results showed that individuals aligned their self-presentations with traditional gender roles and expectations, and this link depended on their gender. No significant differences according to individuals' sexual orientation or platform type were found. Individuals' (hyper-) gender orientation also related to engagement in traditional gender expressions. Specifically, women with a stronger feminine gender orientation expressed more traditional femininity in their MDA profiles. For men, no significant associations between (aspects of) a masculine gender orientation and expressing traditional masculinity in their MDA profiles were found. Future research should further disentangle selective gendered self-presentations.

The Health Narratives Research Group (HeNReG): A self-direction process offered to help decrease burnout in public health nurse practitioners.

Founded in accordance with 19th century sex roles and public health concerns, nursing evolved as other-directed, dependent on physician-focused diagnosis, prescription decisions, and public health advancements. The result of this other direction is that public health nurse practitioners have endured significant workplace stress resulting in burnout, especially during COVID-19. To help decrease their burnout, nurses require development of self-direction. The Health Narratives Research Group (HeNReG) has the potential to reduce burnout in nurse practitioners by encouraging the development of self-direction. The HeNReG process is presented through historically analyzed documents regarding reducing burnout in health researchers by developing self-direction including: (1) three years of archived year-end feedback results provided by participants, (2) archived participant responses to specific HeNReG-related writing prompts, and (3) a comparison of HeNReG results with the outcomes of resilience programs. The conclusion-the HeNReG offers an effective option for reducing burnout in health researchers that has the potential to decrease nurse practitioner burnout in a way that resilience programs do not. Tailoring the HeNReG process to public health nurses is discussed, inviting future research for reducing burnout in public health nurses.

Coming to Voice as Total Top or Total Bottom: Autobiographical Acts and the Sexual Politics of Versatility on Reddit.

For gay, bisexual, and men who have sex with men (GBMSM), sexual versatility encompasses both insertive (top) and receptive (bottom) sexual practices. By contrast, "total top" and "total bottom" roles are often marginalized by those who advocate versatile roles for GBMSM. This article explores how GBMSM "come to voice" as total tops and total bottoms on the social media platform, Reddit. Reading posts and comments as autobiographical acts, the article analyses how total tops and bottoms assert the validity of their claim to sexual knowledge as total top or total bottom while negotiating the sexual politics of versatility on Reddit and beyond.

Long-term female bias in sex ratios across life stages of Harpy Eagle, a large raptor exhibiting reverse sexual size dimorphism.

The primary (PSR), secondary (SSR) and adult (ASR) sex ratios of sexually reproducing organisms influence their life histories. Species exhibiting reversed sexual size dimorphism (RSD) may imply a higher cost of female production or lower female survival, thus generating biases in PSR, SSR and/or ASR towards males. The Harpy Eagle is the world's largest eagle exhibiting RSD. This species is found in the Neotropical region and is currently threatened with extinction. We used molecular markers to determine the sex of 309 Harpy Eagles spanning different life stages-eaglets, subadults and adults-from 1904 to 2021 within the Amazon Rainforest and Atlantic Forest. Sex ratios for all life stages revealed a female-biased deviation across all periods and regions. Our results suggest that the population bias towards females is an evolutionary ecological pattern of this species, and SSR and ASR likely emerged from the PSR. This natural bias towards females may be compensated by an earlier sexual maturation age of males, implying a longer reproductive lifespan and a higher proportion of sexually active males. A better understanding of the Harpy Eagle's life history can contribute to understanding sex-role evolution and enable more appropriate conservation strategies for the species.

Effects of season length and uniparental care efficacy on the evolution of parental care.

Parental care patterns differ enormously among and even within species. This is exemplified by Chinese penduline tits Remiz consobrinus, where biparental care, female-only care, male-only care and biparental desertion all occur in the same population; moreover, the distribution of these care patterns differs systematically between populations. The eco-evolutionary determinants of this diversity are largely unknown. We developed an individual-based model that allows us to investigate the effects of season length and offspring needs (expressed by the efficacy with which a clutch can be raised by a single parent) on the evolution of parental care patterns. The model is largely conceptual, aiming at general conclusions. However, to keep the model realistic, its set-up and the choice of parameters are motivated by field studies on Chinese penduline tits. Exploring a wide range of parameters, we investigate how parental care patterns are affected by season length and offspring needs and whether and under what conditions diverse parental care patterns can stably coexist. We report five main findings. First, under a broad range of conditions, different care patterns (e.g. male care and biparental care) coexist at equilibrium. Second, for the same parameters, alternative evolutionary equilibria are possible; this can explain differences in care patterns across populations. Third, rapid evolutionary transitions can occur between alternative equilibria; this can explain the often-reported evolutionary lability of parental care patterns. Fourth, season length has a strong but nonmonotonic effect on the evolved care patterns. Fifth, when uniparental care efficacy is low, biparental care tends to evolve; however, in many scenarios uniparental care is still common at equilibrium. In addition, our study sheds new light on Trivers' hypothesis that the sex with the highest prezygotic investment is predestined to invest more postzygotically as well. Our study highlights that diversity in parental care can readily evolve and it shows that even in the absence of environmental change parental care patterns can be evolutionary labile. In the presence of directional environmental change, systematic shifts in care patterns are to be expected.

Sex-specific assumptions and their importance in models of sexual selection.

Sexual selection is a field coloured by tension and contrasting views. One contested claim is the causal link from the definition of the sexes (anisogamy) to divergent selection on the sexes. Does theory truly engage with this claim? We survey the extent to which theory makes sex-specific assumptions and engages with anisogamy, and discuss these issues in a broader context. The majority of theory in sexual selection makes sex-specific assumptions and does not engage with the definition of the sexes. While this does not invalidate existing results, debates and criticisms regarding sexual selection force us to think deeper about its logical foundations. We discuss ways to strengthen the foundations of sexual selection theory by relaxing central assumptions.

The Role of Gender, Sexual Assault History, and Sexism in Endorsement of Rape Myths Among College Students.

The present study examined the roles of sexual victimization history, sexism toward women, and sexism toward men in the gender difference in rape myth acceptance. The data were obtained from 2,011 male and female college students who completed an online survey. The results suggested that gender had a significant indirect effect on rape myth acceptance via sexual assault history and several forms of sexist beliefs. The findings supported the importance of considering additional antecedents of rape myths in research, as well as in programming geared toward preventing sexual assault and improving support for survivors.

Prenatal Sex Role Stereotypes: Gendered Expectations and Perceptions of (Expectant) Parents.

People assign attributes to a different degree to other persons depending on whether these are male or female (sex role stereotypes). Such stereotypes continue to exist even in countries with lower gender inequality. The present research tested the idea that parents develop sex role consistent expectations of their babies' attributes based on fetal sex (by ultrasound diagnostic), as well as gendered perceptions of their recently newborn babies. A total of 304 dyads of predominantly White expecting parents from Germany were followed over the course of pregnancy until after the birth and completed a sex role inventory on their babies' expected (before birth) as well as perceived traits (after birth). Specifically, they rated to what extent they expected their babies to have normatively feminine traits (e.g., soft-spoken and warm) and normatively masculine traits (e.g., independent and assertive) twice before birth (first half of pregnancy, six weeks before due date) and to what extent they perceived their baby to have these traits eight weeks after birth. The results suggested that fathers held gendered expectations and perceptions, whereas mothers did not. These results suggest that male and female babies are likely to encounter sex role stereotypes about their alleged attributes as soon as their birth.

Androgen-armoured amazons: reversed sex roles in coucals are associated with testosterone in females but not males.

In some species, sexual selection is stronger in females than males. In classically polyandrous birds, for instance, females compete for mating opportunities and males care for offspring. Sex steroids such as testosterone have been suggested to regulate the behaviours of 'role-reversed' females and males, but comparative studies did not find evidence for a role of testosterone in relation to sex roles. However, the large variability of hormone measurements across laboratories may prevent detecting subtle differences in hormone levels. To circumvent this caveat, I compared sex steroid concentrations of females and males of two closely related and cohabiting species with different mating systems: the classically polyandrous black coucal (Centropus grillii) and the monogamous white-browed coucal (C. superciliosus). Baseline and gonadotropin-releasing hormone (GnRH)-induced testosterone concentrations were twice as high in female black coucals than female white-browed coucals, and the low pre-breeding progesterone concentrations of female black coucals were consistent with progesterone's modulatory role during agonistic interactions in this species. Baseline and GnRH-induced testosterone and progesterone concentrations did not differ between males of both species. This study provides first evidence that elevated testosterone is associated with sex-role-reversed traits in females, whereas low levels of testosterone may not be necessary to facilitate sex-role reversal in males.

Sex roles and sex ratios in animals.

In species with separate sexes, females and males often differ in their morphology, physiology and behaviour. Such sex-specific traits are functionally linked to variation in reproductive competition, mate choice and parental care, which have all been linked to sex roles. At the 150th anniversary of Darwin's theory on sexual selection, the question of why patterns of sex roles vary within and across species remains a key topic in behavioural and evolutionary ecology. New theoretical, experimental and comparative evidence suggests that variation in the adult sex ratio (ASR) is a key driver of variation in sex roles. Here, we first define and discuss the historical emergence of the sex role concept, including recent criticisms and rebuttals. Second, we review the various sex ratios with a focus on ASR, and explore its theoretical links to sex roles. Third, we explore the causes, and especially the consequences, of biased ASRs, focusing on the results of correlational and experimental studies of the effect of ASR variation on mate choice, sexual conflict, parental care and mating systems, social behaviour, hormone physiology and fitness. We present evidence that animals in diverse societies are sensitive to variation in local ASR, even on short timescales, and propose explanations for conflicting results. We conclude with an overview of open questions in this field integrating demography, life history and behaviour.

"You Throw Like a Girl!": Young Children's Gender Stereotypes About Object Control Skills.

Purpose: Understanding if children hold stereotypes about motor skills, may partially explain differences in object control performance between young boys and girls. Therefore, the purpose of this study was to examine whether young boys and girls held stereotypes related to object control skills. Methods: Children (N = 84) ages three years four months to five years seven months (Mage = 4.6 years, SD = .58) completed the Test of Gross Motor Development-Second Edition and a modified version of the Children's Occupations, Activities and Traits Measure. Spearman Rho correlations examined associations between children's stereotypes and actual object control skills performance. We then examined differences between boys' and girls' gender stereotypes (three for each category) and object control skills via independent samples t-tests. Results: Results showed significant associations between gender stereotypes toward object control skills and actual object control skills for girls (ρ = -.31--.53, p < .05) but not for boys (ρ = .10-.14, p > .05). Concurrently, girls showed significantly lower object control skills than boys (t[82] = 2.01; p = .042, d = .44) as well as significantly higher gender stereotypes across all three categories (p < .05, d = .54-1.77). Conclusion: These data indicated that girls, not boys, held gender stereotypes about object control skills in concert with lower object control skill performances. Future research should evaluate the impacts of an integrated gross motor intervention which seeks to change gender stereotypes and concurrently improve object control skill performance.

What Amphibians Can Teach Us About the Evolution of Parental Care.

Parenting is considered a key evolutionary innovation that contributed to the diversification and expansion of vertebrates. However, we know little about how such diversity evolved. Amphibians are an ideal group in which to identify the ecological factors that have facilitated or constrained the evolution of different forms of parental care. Among, but also within, the three amphibian orders-Anura, Caudata, and Gymnophiona-there is a high level of variation in habitat use, fertilization mode, mating systems, and parental sex roles. Recent work using broad phylogenetic, experimental, and physiological approaches has helped to uncover the factors that have selected for the evolution of care and transitions between different forms of parenting. Here, we highlight the exceptional diversity of amphibian parental care, emphasize the unique opportunities this group offers for addressing key questions about the evolution of parenting, and give insights into promising novel directions of research.

Let's just do it: sexual arousal's effects on attitudes regarding sexual consent.

Misperception of others' sexual willingness or consent is widely considered to contribute to sexual coercion. Sexual arousal is commonly present among those in situations with potential to result in sexual assault. The current research tests the effects of sexual arousal on related attitudes: including those toward token resistance, assertive sexual strategies, and affirmative consent. Sexual arousal was primed through a narrative writing paradigm. Results indicate sexual arousal led all participants to be more likely to endorse belief in female token resistance, and led women to more strongly endorse men's assertive sexual strategies. Implications for research on sexual consent are discussed.

Mothers' Domestic Responsibilities and Well-Being During the COVID-19 Lockdown: The Moderating Role of Gender Essentialist Beliefs About Parenthood.

The present work investigates how the increased domestic responsibilities created by the Spring 2020 lockdown of the COVID-19 pandemic in Norway and gender ideologies relate to the well-being of mothers with elementary school children. In June 2020, we conducted a cross-sectional online study including current and retrospective measures with 180 mothers (M age = 39.96 years, SD = 6.11) of elementary school children across Norway. First, in line with earlier research on the strain of the pandemic on parents, and especially mothers, we found that Norwegian mothers' well-being during the lockdown significantly declined compared to before the lockdown (both measured retrospectively). Furthermore, mothers' well-being after the Spring 2020 lockdown did not immediately return to pre-lockdown levels. Finally, we predicted that gender ideologies (i.e., essentialist beliefs about parenthood) would exacerbate the negative impact of increased domestic responsibilities (i.e., childcare and housework) on mothers' well-being (i.e., higher standard-higher stress hypothesis). As predicted, for mothers who more strongly endorsed the belief that mothers are instinctively and innately better caretakers than fathers, perceptions of increased domestic responsibilities were associated with lower well-being post-lockdown. These findings point to the specific challenges mothers face in times of crisis, and the importance of addressing and confronting seemingly benevolent ideologies about motherhood that place additional burdens on women.

Gender Differences in Self-Estimated Intelligence: Exploring the Male Hubris, Female Humility Problem.

Despite evidence from cognitive psychology that men and women are equal in measured intelligence, gender differences in self-estimated intelligence (SEI) are widely reported with males providing systematically higher estimates than females. This has been termed the male hubris, female humility effect. The present study explored personality factors that might explain this. Participants (N = 228; 103 male, 125 female) provided self-estimates of their general IQ and for Gardner's multiple intelligences, before completing the Cattell Culture Fair IQ test as an objective measure of intelligence. They also completed the Bem Sex Role Inventory (BSRI) as a measure of sex-role identification, and measures of general and academic self-esteem. Both gender and sex-role differences were observed for SEI, with males and participants of both genders who scored high in masculinity offering higher self-estimates. By comparing estimated and observed IQ, we were able to rule out gender differences in overall accuracy but observed a pattern of systematic underestimation in females. An hierarchical multiple regression showed significant independent effects of gender, masculinity, and self-esteem. Mixed evidence was observed for gender differences in the estimation of multiple intelligences, though moderately sized sex-role differences were observed. The results offer a far more nuanced explanation for the male hubris, female humility effect that includes the contribution of sex role identification to individual and group differences.

The Influence of Gender Categories and Gender Stereotypes on Young Children's Generalizations of Biological and Behavioral Characteristics.

We examined the influence of categorization and stereotyping on young children's (N = 96; 39 to 71 months of age) use of gender to make generalizations regarding novel biological and behavioral characteristics. Participants were asked to sort pictures of children according to either gender, common gender stereotypes, or shirt color. Then participants performed a triad inductive reasoning task. Children in the Stereotype condition consistently generalized on the basis of gender, but performance was inconsistent in the absence of stereotyping. Results are discussed in relation to variability in early gender cognition.

Patients with disorders of sex development undergoing surgical treatment: A psychosocial evaluation in adolescence.

The surgical outcomes of disorders on sex development (DSD) are comparatively well studied in the literature, whereas studies investigating its impacts on mental health are scarce. In this study, we aimed to evaluate psychiatric diagnoses, sex roles, quality of life, and adolescents who were surgically treated because of DSD as well as parental attitudes in their parents. The study group consisted of 19 patients diagnosed with DSD and the control group consisted of 20 age- and gender-matched healthy peers. The Kiddie-Schedule for Affective Disorders and Schizophrenia was performed by a child and adolescent psychiatrist to assess the psychiatric diagnoses. To evaluate quality of life (QoL) and sex roles, The Pediatric Quality of Life Inventory (PedsQL), and the Bem Sex Role Inventory were used, respectively. Mothers completed the PedsQL-Parent Form and the Parental Attitude Research Instrument (PARI). Of 19 children in the patient group, 14 (73.7%) had a past or current history of at least one psychiatric disorder. The most common psychiatric disorder was major depression. There was no significant difference between the two groups in terms of sex roles. A statistically significant difference was found between the study and control groups in four factor scores of the PARI. While there was no significant difference between the groups in terms of the children's QoL scores, parent-proxy reports of psychosocial health scores and total QoL scores of the study group were significantly lower than the controls. This finding shows that parents perceived the QoL of their children with DSD as worse than their healthy peers, probably due to their concerns for the future. In conclusion, it is important to identify and treat the psychiatric disorders concomitant in patients with DSD.