Intrasexual Competition For Mates Research Articles

"A Streetcar Named Instagram Desire": Evolutionary Psychological Perspectives on the Multifarious Human Desires That Shape Instagram Selfie-and-Groupfie Cultures.

Instagram not only offers an arena for the fulfillment of basic human desires but also cultivates new types of multifaceted desires and consumptions in Web 2.0 environments. This study aims to examine a wide variety of dispositional, psychological, and attitudinal predictors of Instagram consumption and selfie-and-groupfie cultures. Three cross-sectional surveys (Study 1 (N = 108); Study 2 (N = 140); Study 3 (N = 557)) were conducted, and empirical data were analyzed using structural equation modeling (SEM) with Mplus 8.0. Study 1 shows associations among appearance-related self-confidence, appearance-related actual–ideal self-discrepancy, materialism, and Instagram consumption. Study 2 confirms relationships among weight status perception, self-esteem, eating disorder, malicious envy, and Instagram consumption intensity. Study 3 further demonstrates dynamic associations among eating disorders, perceived mate value, narcissistic grandiosity, envy, social comparison, intrasexual competition for mates, and frequency of posting selfies/groupfies on Instagram. Theoretical contributions to the psychosocial and human aspects of the Web 2.0 digital culture, managerial implications for online dating cultures, and practical implications for consumption markets including social media-based health communication, cultural communication, and marketing communication are discussed.

Ewe are what ewe wear: bigger horns, better ewes and the potential consequence of trophy hunting on female fitness in bighorn sheep.

In polygynous species, secondary sexual traits such as weapons or elaborate ornaments have evolved through intrasexual competition for mates. In some species, these traits are present in both sexes but are underdeveloped in the sex facing lower intrasexual competition for mates. It is often assumed that these underdeveloped sexually selected traits are a vestige of strong sexual selection on the other sex. Here, we challenge this assumption and investigate whether the expression of secondary sexual traits is associated with fitness in female bighorn sheep. Analyses of 45 years of data revealed that female horn length at 2 years, while accounting for mass and environmental variables, is associated with younger age at primiparity, younger age of first offspring weaned, greater reproductive lifespan and higher lifetime reproductive success. There was no association between horn length and fecundity. These findings highlight a potential conservation issue. In this population, trophy hunting selects against males with fast-growing horns. Intersexual genetic correlations imply that intense selective hunting of large-horned males before they can reproduce can decrease female horn size. Therefore, intense trophy hunting of males based on horn size could reduce female reproductive performance through the associations identified here, and ultimately reduce population growth and viability.

"Death and Love Amid the COVID-19 Pandemic": Effects of Pathogen Threats on Online Dating and Social Distancing From Life-History Strategy Perspectives.

Drawing from the terror management theory (TMT) and evolutionary perspectives of Life-History Strategy, a between-subject online experiment examined the interaction effects of pre-existing death anxiety, fear-inducing media content (coronavirus threat vs. gun violence threat vs. low threat mental disorder), and intrasexual competition for mates on online dating intentions and social distancing intentions during the COVID-19 pandemic. Results indicate the interaction effects of participants' pre-experimental death anxiety and different types of fear-inducing media content on perceived fear and intention to use online dating websites/apps as well as the interaction effects of pre-experimental intrasexual competitiveness and fear-inducing media content on social distancing intention in the context of online dating. Theoretical contributions to the terror management literature and practical implications for the online dating industry are discussed.

The dark ventral patch: A bimodal flexible trait related to male competition in red deer.

Sexual signals play a central role in male-male competition in polygynous species. In red deer (Cervus elaphus), male’s ventral area become dark during the rutting season due to urine spraying behaviour and retains many chemical compounds potentially revealing individual features. Here we investigate the variation in size of this trait, exploring its relationship with age and male competitive features such as antlers or body size, as well as populational level of intrasexual competition for mates. We found that the size of the dark ventral patch followed a clearly bimodal distribution, i.e. males mostly expressed the full-size trait or just developed a very small one. For these two groups of males according to trait expression, the relationships of trait size with age and antler size differed. Populational level of intrasexual competition appeared to affect the relationship between antler size and the probability of a fully developed ventral patch. These results indicate that the trait encodes information on body size, antler size, age and populational level of mate competition, thus suggesting a role in signalling male’s competitive features and willingness to allocate reproductive effort within a particular season.

Experimentally induced intrasexual mating competition and sex-specific evolution in female and male nematodes.

Sexual dimorphism in life history traits and their trade‐offs is widespread among sexually reproducing animals and is strongly influenced by the differences in reproductive strategies between the sexes. We investigated how intrasexual competition influenced specific life history traits, important to fitness and their trade‐offs in the outcrossing nematode Caenorhabditis remanei. Here, we altered the strength of sex‐specific selection through experimental evolution with increased potential for intrasexual competition by skewing the adult sex ratio towards either females or males (1:10 or 10:1) over 30 generations and subsequently measured the phenotypic response to selection in three traits related to fitness: body size, fecundity and tolerance to heat stress. We observed a greater evolutionary change in females than males for body size and peak fitness, suggesting that females may experience stronger net selection and potentially harbour higher amounts of standing genetic variance compared to males. Our study highlights the importance of investigating direct and indirect effects of intrasexual competition in both sexes in order to capture sex‐specific responses and understand the evolution of sexual dimorphism in traits expressed by both sexes.

Male voice pitch mediates the relationship between objective and perceived formidability

Acoustic signals function in intrasexual mating competition in a wide variety of species, including humans. The low voice pitch of human males has been proposed to represent an honest signal of formidability. Although voice pitch in men affects perceptions of size and dominance, it is relatively weakly associated with objective measures of formidability such as body size and strength. As a result, some authors have argued that low male voice pitch is not a valid signal of formidability but is deceptive and salient only because it hijacks a tendency to perceive lower frequency sounds as emanating from larger sources. In this paper, we consider theoretical and empirical issues associated with this perceptual exploitation hypothesis and ask whether male voice pitch transmits information about formidability. We utilize mediation models to investigate whether male voice pitch is an honest signal of formidability in data collected from university students in the U.S. (n = 231 male speakers, 565 male raters) and Canada (n = 74 male speakers, 108 female raters, 65 male raters). In both data sets, male voice pitch mediated the relationship between objective (measured by height) and perceived formidability. Collectively, these results indicate that men’s voice pitch transmits information about formidability from signaler to receiver.

Unexpected reproductive fidelity in a polygynous frog.

Polygynous mating systems with group fidelity are a common animal organization, typically consisting of multiple females in a mated group with a single male for an extended period (sometimes referred to as harem polygyny). Single-male polygyny with reproductive fidelity occurs in invertebrates, bony fishes, and some tetrapods, such as lizards, mammals, and birds. In amphibians, reproductive fidelity in polygynous groups is not fully demonstrated. Combining data on larval development, molecular paternity assignment, and in situ behavioral observations, we reveal high fidelity during a prolonged breeding season in a Neotropical polygynous frog. Males dominate scarce breeding sites, guarding offspring, and mating exclusively with multiple females that exhibit dominance rank. This system likely evolved in response to intense competition for breeding sites and intrasexual competition for mates.

A thousand times more beautiful: Priming competitor derogation in women

Prior research on cognitive priming for situations involving potential infidelity indicates that women are vigilant to potential threats to their romantic relationships. Here we examined whether women can be effectively primed to initiate one strategy for intrasexual mating competition, competitor derogation, which includes behaviors individuals undertake to decrease the value of a rival relative to oneself. Using a pre-post within-subjects research design, women evaluated photographed womens’ attractiveness, friendliness, intelligence, and attributable blame for an infidelity, as well as their own relative attractiveness, desirability, and attributable blame. Short vignettes describing a hypothetical situation of a mate diverting his interest toward another woman served as primes of possible threat to one’s romantic relationship. After exposure to the primes, women’s ratings of the photographed women decreased, while allocation of blame increased, despite the fact that these women were not involved in the primes and hence, did not directly serve as threats to the relationship. The participants were also less likely to want to become friends with the photographed women, or recommend her for friendship. Self-ratings remained stable, possibly indicating one’s self-perceived mate value is not influenced by temporary situations, akin to how baseline self-esteem is resistant to short-term fluctuations. Directions for future work are provided.

Cyberbullying, cyber aggression, and cyber victimization in relation to adolescents' dating and sexual behavior: An evolutionary perspective.

This study examined adolescents' cyberbullying, cyber aggression, and cyber victimization from an evolutionary perspective, extending previous research showing that traditional forms of bullying, aggression, and victimization are associated with reproductively relevant outcomes. Consistent with hypotheses based on theory and research linking bullying and aggression to intrasexual competition for mates, results indicated that cyber victimization was positively associated with a number of dating and sexual partners. Findings for cyber aggression were more complex, depending on the degree of cyber victimization experienced by the perpetrator, and the balance of power between the perpetrator and victim. Specifically, nonbullying cyber aggression by perpetrators with equal or less power than the victim had stronger positive relations with the number of dating or sexual partners when perpetrators experienced a high level of cyber victimhood. In contrast, cyberbullying by perpetrators with more power than the victim was negatively associated with the number of dating partners when the perpetrators' exposure to cyber victimization was low. Although cyber aggression and cyber victimization are new forms of aggression that involve the use of modern electronic devices, the results of this study demonstrate the usefulness of viewing this behavior from an evolutionary perspective and show that adolescents are likely to use cyber aggression against rivals in the context of intrasexual competition for mates.

“Sneering Civility”: Female Intrasexual Competition for Mates in Jane Austin’s Novels

“Sneering Civility”: Female Intrasexual Competition for Mates in Jane Austin’s Novels

Evolutionary Psychology of Eating Disorders: An Explorative Study in Patients With Anorexia Nervosa and Bulimia Nervosa.

Prior research on non-clinical samples has lent support to the sexual competition hypothesis for eating disorders (SCH) where the drive for thinness can be seen as an originally adaptive strategy for women to preserve a nubile female shape, which, when driven to an extreme, may cause eating disorders. Restrictive versus impulsive eating behavior may also be relevant for individual differences in allocation of resources to either mating effort or somatic growth, reflected in an evolutionary concept called “Life History Theory” (LHT). In this study, we aimed to test the SCH and predictions from LHT in female patients with clinically manifest eating disorders. Accordingly, 20 women diagnosed with anorexia nervosa (AN), 20 with bulimia nervosa (BN), and 29 age-matched controls completed a package of questionnaires comprising measures for behavioral features and attitudes related to eating behavior, intrasexual competition, life history strategy, executive functioning and mating effort. In line with predictions, we found that relatively faster life history strategies were associated with poorer executive functioning, lower perceived own mate value, greater intrasexual competition for mates but not for status, and, in part, with greater disordered eating behavior. Comparisons between AN and BN revealed that individuals with BN tended to pursue a “fast” life history strategy, whereas people with AN were more similar to controls in pursuing a “slow” life history strategy. Moreover, intrasexual competition for mates was significantly predicted by the severity of disordered eating behavior. Together, our findings lend partial support to the SCH for eating disorders. We discuss the implications and limitations of our study findings.

Group movements in response to competitors' calls indicate conflicts of interest between male and female grey-cheeked mangabeys.

Long-distance vocalizations mediate spacing patterns by allowing groups to choose whether to draw close enough to a neighbor to initiate a short-range interaction. It is unclear, however, whether the patterning of calls and the resulting movements are invariant or change in response to social and ecological variables. In this study, we compare the impact of long-distance calls on neighboring groups' movements in two populations of grey-cheeked mangabeys (Lophocebus albigena) in Uganda, which differed widely in group density and food availability. We monitored movement responses of target groups to both naturally occurring and experimentally simulated "whoop-gobble" vocalizations of neighboring adult males to test whether responses indicated mate and food defense. When defending access to fertile females, males might coerce group members to move away from neighboring males; when defending fitness-limiting food resources, however, groups might approach and attempt to evict neighbors. Controlling for pre-call movement prior to the vocalization, we found no difference in group responses between the low- and high-density populations, and little support for either form of defense. Mangabey groups generally continued moving in their original direction, albeit at a slower pace, and deviations from this pattern were predictable: they avoided nearby callers but approached distant callers; they approached if the caller was in the area where home ranges overlapped; and approached when their own group contained multiple peak-estrous females. The effect of multiple fertile females potentially indicates a breakdown of male control as a result of within-group intrasexual mating competition, and greater-than-expected female control over travel movements. As suspected, grey-cheeked mangabeys use neighbors' long-distance calls to maintain a spatial buffer between groups but changes in group movements indicate a conflict between male and female interests.

“The Paradox of Narcissus and Echo in the Instagram Pond” in Light of the Selfie Culture from Freudian Evolutionary Psychology: Self-Loving and Confident but Lonely

Drawing from the Freudian evolutionary psychology of narcissism and the literature on social media popularity, this article addresses the central theme revolving around “The Paradox of Digital Narcissists in the Instagram Pond” in light of the selfie/groupie culture. A cross sectional survey was conducted among 398 Instagram users (236 males and 162 females) recruited from Amazon M-Turk. Structural equation modeling analyses using Mplus 7.4 propose an integrative model of narcissism and reveal dynamic relationships among users’ narcissism, self-discrepancy, self-confidence, intrasexual competition for mates, need to belong, need for popularity, loneliness, number of selfie/groupie posts on Instagram, and number of Instagram followers/followings.

Competition for food in 2 populations of a wild-caught fish.

Aggressive behavior when competing for resources is expected to increase as the ratio of competitors-to-resource ratio (CRR) units increases. Females are expected to be more aggressive than males when competing for food when body size is more strongly related to reproductive success in females than in males, whereas aggression is predicted to decrease under high ambient predation risk by natural selection. Under the risk allocation model, however, individuals under high ambient predation risk are expected to be more aggressive, and forage more in the absence of imminent risk than their low risk counterparts. An interaction between adult sex ratio (i.e., adult males/females), ambient predation risk (high vs. low), and sex on intrasexual competition for mates in Trinidadian guppies Poecilia reticulata has been shown. The interaction suggested an increase in aggression rates as CRR increased, except for males from the high predation population. To compare the patterns of competition for food versus mates, we replicated this study by using food patches. We allowed 4 male or 4 female guppies from high and low predation populations to compete for 5, 3, or 1 food patches. The foraging rate was higher in a high rather than low ambient predation risk population. Surprisingly, CRR, sex, and population of origin had no effect on aggression rates. Despite other environmental differences between the 2 populations, the effect of ambient predation risk may be a likely explanation for differences in foraging rates. These results highlight the importance for individuals to secure food despite the cost of competition and predation.

Body dissatisfaction and disordered eating in androphilic and gynephilic men and women

According to the theory of intra-sexual competition for mates, androphilic individuals (i.e., sexually interested in men) are expected to emphasize their physical appearance, and be less satisfied with their bodies, compared to gynephilic individuals (i.e., sexually interested in women). To test this theory against the objectification theory and the minority stress theory of body dissatisfaction and disordered eating, we measured body dissatisfaction, disordered eating, and body mass index (BMI) in both androphilic and gynephilic men and women in a large population-based sample (N=8007). Compared to gynephilic men, androphilic men were more likely to be dissatisfied with their bodies and display disordered eating. Gynephilic women were more dissatisfied with their bodies compared to androphilic women. Women were, on average, more likely to be dissatisfied with their bodies and display disordered eating compared to men. Theoretical implications of the findings were discussed.

The relationship between testosterone and long-distance calling in wild male chimpanzees.

Long-distance calling is a common behaviour in animals that has various important social functions. At a physiological level, calling is often mediated by gonadal hormones such as testosterone (T), particularly when its function is linked to intra-sexual competition for mates or territory. T also plays an important role in the development of vocal characteristics associated with dominance in humans. However, the few available studies of T and vocal behaviour in non-human primates suggest that in primates T has less influence on call production than in other animals. We tested this hypothesis by studying the relationship between T concentrations and pant hooting in wild male chimpanzees (Pan troglodytes schweinfurthii) of the Kanyawara community in the Kibale National Park, Uganda. We found three kinds of correlation. Hourly T averages were positively associated with hourly rates of pant-hooting. Monthly T levels were likewise correlated with monthly rates of pant hooting after controlling for other influences such as fission-fusion rates. Finally, males with high T levels had higher peak frequency at the start of the call climax. These results suggest that T affects the production of pant-hoots in chimpanzees. This implies that the pant-hoot call plays a role in male-male competition. We propose that even in cognitively sophisticated species, endocrine mechanisms can contribute to regulating vocal production.

Sexually selected sentinels? Evidence of a role for intrasexual competition in sentinel behavior.

Although the evolutionary mechanisms that favor investment in cooperative behaviors have long been a focus of research, comparatively few studies have considered the role that sexual selection may play. For example, evolutionary explanations for sentinel behavior (where 1 individual assumes an elevated position and scans the surroundings while other group members forage nearby) have traditionally focused on the inclusive fitness benefits arising from its effects on predation risk, while its potential role in defense against intrasexual competitors remains largely unexplored. Here, we provide experimental evidence of a role for sentinel behavior in intrasexual competition, in a cooperatively breeding songbird, the white-browed sparrow weaver (Plocepasser mahali). First, dominant males sentinel substantially more than other group members (even when controlling for variation in age and body condition), consistent with a role for sentineling in intrasexual competition for mates and/or territory. Second, experimental playback of an unfamiliar male's solo song elicited a marked increase in sentineling by the dominant male, and the vocal response to the playback also positively predicted his sentinel effort following the simulated intrusion. A second experiment also suggests that sentineling may facilitate mounting rapid anti-intruder responses, as responses to intruder-playback occurred significantly earlier when the dominant male was sentineling rather than foraging at playback onset. Together, our findings provide rare support for the hypothesis that sentinel behavior plays a role in intrasexual competition, and so highlight the potential for sexually selected direct benefits to shape its expression in this and other social vertebrates.

Mate choice plasticity in a coral reef fish

Mate choice and intrasexual mating competition are the processes that drive sexual selection and can be interrelated in multiple ways. Female preference may be altered by exposure to male-male interactions. This could happen because of a reduced ability of females to evaluate males in the presence of male-male competition or because females use information from male interactions to form mating preferences. In this study, female preference for a male tail ornament was measured in the presence and absence of male-male competition in a coral reef fish, the damselfish Chrysiptera cyanea. Despite the striking colors of coral reef fishes, few studies have investigated the role of their coloration in the context of sexual selection. When male-male interactions were prevented, females showed a temporal change in preference with respect to male tail coloration, preferring brightly colored males early in the study period and dull males later on. Thus, females did not become less selective, but reversed their preference function within the breeding season. When males were allowed to interact, male-male agonistic interactions were extremely frequent and male courtship activity was strongly reduced. In this situation, females still displayeda sexual interest in males, but were indiscriminate with regard to male tail coloration.Taken together, these results provide compelling evidence for plasticity of female matingpreference, related to the social context and time in the breeding season.

The role of fecundity and sexual selection in the evolution of size and sexual size dimorphism in New World and Old World voles (Rodentia: Arvicolinae)

Evolutionary ecologists dating back to Darwin (1871) have sought to understand why males are larger than females in some species, and why females are the larger sex in others. Although the former is widespread in mammals, rodents and other small mammals usually exhibit low levels of sexual size dimorphism (SSD). Here, we investigate patterns of sexual dimorphism in 34 vole species belonging to the subfamily Arvicolinae in a phylogenetic comparative framework. We address the potential role of sexual selection and fecundity selection in creating sex differences in body size. No support was found for hyperallometric scaling of male body size to female body size. We observed a marginally significant relationship between SSD and the ratio of male to female home range size, with the latter being positively related to the level of intrasexual competition for mates. This suggests that sexual selection favours larger males. Interestingly, we also found that habitat type, but not mating system, constitutes a strong predictor of SSD. Species inhabiting open habitats – where males have extensive home ranges in order to gain access to as many females as possible – exhibit a higher mean dimorphism than species inhabiting closed habitats, where females show strong territoriality and an uniform distribution preventing males to adopt a territorial strategy for gaining copulations. Nonetheless, variation in the strength of sexual selection is not the only selective force shaping SSD in voles; we also found a positive association between female size and litter size across lineages. Assuming this relationship also exists within lineages (i.e. fecundity selection on female size), this suggests an additional role for variation in the strength of fecundity selection shaping interspecific differences in female size, and indirectly in SSD. Therefore our results suggest that different selective processes act on the sizes of males and females, but because larger size is favoured in both sexes, SSD is on average relatively small.

Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchus obscurus)

Males in polygamous species often engage in intrasexual competition for mates. If females actively evade mating attempts, it may benefit males to cooperate to restrict female movement, as has been found in some mammals. We tested if male dusky dolphins (Lagenorhynchus obscurus (Gray, 1828)) cooperate or compete during group mating chases. If they cooperate, then the per-male probability of copulating should increase with group size; if they compete, then the probability should decrease. We followed mating groups by boat during the breeding season (October 2013 – January 2014) off Kaikoura, New Zealand. The copulation rate per male decreased with increasing group size and with the number of noncopulating males in proximity to a copulating female. Male dusky dolphins have multiple mates and appear to use sperm and exploitative scramble competition. Males may remain in mating groups despite competition because there are alliances within the groups, they are unable to exclude rivals from joining a group, the time and energy costs of searching for unescorted females exceed the costs of reduced mating opportunities in a group, they receive other direct or indirect benefits that offset the costs of reduced mating opportunities, or they are in the group largely for social learning rather than procreation.