Journal articles: 'Female intrasexual competition'

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Mealey, Linda. "Evolutionary models of female intrasexual competition." Behavioral and Brain Sciences 22, no. 2 (April 1999): 234. http://dx.doi.org/10.1017/s0140525x99451817.

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Female competition generally takes nonviolent form, but includes intense verbal and nonverbal harassment that has profound social and physiological consequences. The evolutionary ecological model of competitive reproductive suppression in human females, might profitably be applied to explain a range of contemporary phenomena, including anorexia.

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Grant, James W. A., and Patricia E. Foam. "Effect of operational sex ratio on femalefemale versus malemale competitive aggression." Canadian Journal of Zoology 80, no. 12 (December 1, 2002): 2242–46. http://dx.doi.org/10.1139/z02-217.

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We compared the patterns of femalefemale and malemale competition in Japanese medaka (Oryzias latipes) in response to changes in the operational sex ratio (OSR), the ratio of sexually active members of one sex to sexually active members of the opposite sex. As expected, courtship behaviour and intrasexual aggression were more frequent in males than in females. However, the overall patterns of femalefemale and malemale aggression were similar: intrasexual aggression increased with the OSR (female/male OSR for females and male/female OSR for males), consistent with predictions of mating-systems theory. A comparative analysis of our data and those from three other studies indicated that the rate of intrasexual aggression was greater in males than in females, but the patterns of intrasexual aggression were similar: the rate increased linearly and with a common slope with increasing OSR over a range of 0.43.

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Egan, V. "Female intrasexual competition and intimate partner violence." Personality and Individual Differences 101 (October 2016): 475. http://dx.doi.org/10.1016/j.paid.2016.05.125.

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Fiacco, Serena, Simona Palm-Fischbacher, Jana Campbell, and Ulrike Ehlert. "Measuring female intrasexual competition by the scale for intrasexual competition: a validation of the German version." Archives of Women's Mental Health 22, no. 2 (July 25, 2018): 259–66. http://dx.doi.org/10.1007/s00737-018-0890-6.

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Dijkstra, Peter D., and Ton G. G. Groothuis. "Male-Male Competition as a Force in Evolutionary Diversification: Evidence in Haplochromine Cichlid Fish." International Journal of Evolutionary Biology 2011 (July 13, 2011): 1–9. http://dx.doi.org/10.4061/2011/689254.

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It has been suggested that intrasexual competition can be a source of negative frequency-dependent selection, causing agonistic character displacement and facilitating speciation and coexistence of (sibling) species. In this paper we synthesise the evidence that male-male and female-female competition contributes to cichlid diversification, showing that competition is stronger among same-coloured individuals than those with different colours. We argue that intrasexual selection is more complex because there are several examples where males do not bias aggression towards their own type. In addition, sibling species or colour morphs often show asymmetric dominance relationships. We briefly discuss potential mechanisms that might promote the maintenance of covariance between colour and aggression-related traits even in the face of gene-flow. We close by proposing several avenues for future studies that might shed more light on the role of intrasexual competition in cichlid diversification.

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Robinson, Matthew R., and Loeske E. B. Kruuk. "Function of weaponry in females: the use of horns in intrasexual competition for resources in female Soay sheep." Biology Letters 3, no. 6 (August 21, 2007): 651–54. http://dx.doi.org/10.1098/rsbl.2007.0278.

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In many species, females show reduced expression of a trait that is under sexual selection in males, and this expression is thought to be maintained through genetic associations with the male phenotype. However, there is also the potential for the female trait to convey an advantage in intrasexual conflicts over resources. We tested this hypothesis in a feral population of Soay sheep, in which males and females have a polymorphism for horn development, producing either full (normal horned), reduced (scurred) or no (polled, females only) horns. During the lambing period, females who possessed horns were more likely to initiate and win aggressive interactions, independent of age, weight and birthing status. The occurrence of aggression was also context dependent, decreasing over the lambing period and associated with local density. Our results demonstrate that a trait that confers benefits to males during intrasexual competition for mates may also be used by females in intrasexual competition over resources: males use weaponry to gain mates, whereas females use weaponry to gain food.

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Smith, Henrik G., Ulf Ottosson, and Maria Sandell. "Intrasexual competition among polygynously mated female starlings (Sturnus vulgaris)." Behavioral Ecology 5, no. 1 (1994): 57–63. http://dx.doi.org/10.1093/beheco/5.1.57.

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Frame, Alicia M. "The role of sexual preferences in intrasexual female competition." BMC Evolutionary Biology 12, no. 1 (2012): 218. http://dx.doi.org/10.1186/1471-2148-12-218.

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Townsend, John Marshall. "Male dominance hierarchies and women's intrasexual competition." Behavioral and Brain Sciences 22, no. 2 (April 1999): 235–36. http://dx.doi.org/10.1017/s0140525x9947181x.

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In their competition for higher-status men, women with higher socioeconomic status use indirect forms of aggression (ridicule and gossip) to derogate lower-status female competitors and the men who date them. Women's greater tendency to excuse their aggression is arguably a cultural enhancement of an evolutionarily based sex difference and not solely a cultural construction imposed by patriarchy.

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Sternalski, Audrey, François Mougeot, and Vincent Bretagnolle. "Adaptive significance of permanent female mimicry in a bird of prey." Biology Letters 8, no. 2 (November 9, 2011): 167–70. http://dx.doi.org/10.1098/rsbl.2011.0914.

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Permanent female mimicry, in which adult males express a female phenotype, is known only from two bird species. A likely benefit of female mimicry is reduced intrasexual competition, allowing female-like males to access breeding resources while avoiding costly fights with typical territorial males. We tested this hypothesis in a population of marsh harriers Circus aeruginosus in which approximately 40 per cent of sexually mature males exhibit a permanent, i.e. lifelong, female plumage phenotype. Using simulated territorial intrusions, we measured aggressive responses of breeding males towards conspecific decoys of females, female-like males and typical males. We show that aggressive responses varied with both the type of decoys and the type of defending male. Typical males were aggressive towards typical male decoys more than they were towards female-like male decoys; female-like male decoys were attacked at a rate similar to that of female decoys. By contrast, female-like males tolerated male decoys (both typical and female-like) and directed their aggression towards female decoys. Thus, agonistic responses were intrasexual in typical males but intersexual in female-like males, indicating that the latter not only look like females but also behave like them when defending breeding resources. When intrasexual aggression is high, permanent female mimicry is arguably adaptive and could be seen as a permanent ‘non-aggression pact’ with other males.

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Laxdal, D. "Scramble Competition Polygyny in Platypuses." Australian Mammalogy 20, no. 2 (1998): 305. http://dx.doi.org/10.1071/am98312.

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Platypuses in the Upper Hastings river catchment, near the village of Ellenborough, mid-north coast of New South Wales, occur in small numbers in pools and raceways. Visual observations of platypuses at dawn and dusk during winter-spring breeding seasons included males that wandered, mate searched and attempted forced copulations. No intrasexual aggression between males was observed. Choosy female platypuses seemed to be able to control where and when males could mate. Rare observations of aggression among female and/or juvenile platypuses during summer may have been related to resource defence. Platypuses appear to fit the scheme of 'resources influence female dispersion influences male dispersion'.

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Yong, Lengxob, Benjamin E. Woodall, Michele E. R. Pierotti, and Jeffrey S. McKinnon. "Intrasexual competition and throat color evolution in female three-spined sticklebacks." Behavioral Ecology 26, no. 4 (2015): 1030–38. http://dx.doi.org/10.1093/beheco/arv037.

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Cobey, Kelly D., Christine Klipping, and Abraham P. Buunk. "Hormonal contraceptive use lowers female intrasexual competition in pair-bonded women." Evolution and Human Behavior 34, no. 4 (July 2013): 294–98. http://dx.doi.org/10.1016/j.evolhumbehav.2013.04.003.

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Parma, Valentina, Roberto Tirindelli, Angelo Bisazza, Stefano Massaccesi, and Umberto Castiello. "Subliminally Perceived Odours Modulate Female Intrasexual Competition: An Eye Movement Study." PLoS ONE 7, no. 2 (February 27, 2012): e30645. http://dx.doi.org/10.1371/journal.pone.0030645.

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Hare, Robin M., and Leigh W. Simmons. "Sexual selection maintains a female-specific character in a species with dynamic sex roles." Behavioral Ecology 32, no. 4 (March 25, 2021): 609–16. http://dx.doi.org/10.1093/beheco/arab005.

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Abstract The effects of sexual selection are more conspicuous among male animals, and, as a result, the majority of sexual selection research focuses on males. However, burgeoning evidence suggests that sexual selection also acts on females, and there have been calls for an increased focus on females. Here, we used a multivariate approach to analyze sexual selection in Kawanaphila nartee, a spermatophore gift-giving bushcricket with dynamic sex roles. Early in the breeding season, females compete for males, and, later, when environmental food resources are more abundant, sex roles revert to Darwinian convention. Ear size, which is much greater in females than in males, has been suggested to affect female fitness as females with larger ears are more likely to reach calling males first under sex-role-reversed conditions. We tested this suggestion and found evidence of positive linear and nonlinear correlational selection acting on female ear size early in the breeding season (under reversed sex roles) but not later in the breeding season (under Darwinian sex roles). Interestingly, there was no correlation between mating success and reproductive success (Bateman gradient) at any time during the season. Together, our results indicate that even brief and circumscribed periods of intrasexual competition among females can lead to sexual selection on morphological characters and that this selection may not depend on multiple mating. Considering the wealth of reports in the literature of brief episodes of intrasexual competition among female animals, we recommend increased study of sexual selection acting on females.

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Emlen, Stephen T., and Peter H. Wrege. "Size Dimorphism, Intrasexual Competition, and Sexual Selection in Wattled Jacana (Jacana Jacana), A Sex-Role-Reversed Shorebird in Panama." Auk 121, no. 2 (April 1, 2004): 391–403. http://dx.doi.org/10.1093/auk/121.2.391.

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AbstractWe studied sexual size dimorphism, intrasexual competition, and sexual selection in an individually marked population of Wattled Jacanas (Jacana jacana) in the Republic of Panama. Males are the sole incubators of eggs (28-day incubation) and primary providers of chick care (50–60 days). Females were 48% heavier than, and behaviorally dominant over, males. Females also showed greater development of secondary sexual characters (fleshy facial ornamentation and wing spurs) than males. Both sexes defended territories throughout the year against same-sex conspecifics. Competition for territorial space was intense, and many individuals of both sexes did not become breeders. Resident females further competed with one another to accumulate multiple mates, resulting in a mating system of simultaneous polyandry. Female and male residents (territory holders) were larger, heavier, and more ornamented than adult floaters of the same sex. Larger and heavier females also had more mates than smaller females. Body size was thus a critical predictor of success in intrasexual competition for territories (both sexes) and for mates (females). Three measures of sexual selection—(1) sex difference in the opportunity for sexual selection, (2) female-to-male ratio of potential reproductive rates, and (3) operational sex ratio—each indicated that sexual selection is currently operating more strongly on females than on males (female-to-male ratios ranged from 1.43:1 to 2.22:1). Values of 1.61:1 and 1.43:1 represent the first published quantitative estimates of the opportunity for sexual selection for any sex-role-reversed bird. Our study supports the theory that when increased parental care entails reduced opportunities for future reproduction, asymmetries in parental care behaviors of the sexes can influence the intensity of competition for mates and the direction and strength of sexual selection.

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Adkison, Milo D., Michael B. Ward, and Thomas P. Quinn. "Nest site preference and intrasexual competition in female sockeye salmon, Oncorhynchus nerka." Environmental Biology of Fishes 97, no. 4 (August 6, 2013): 385–99. http://dx.doi.org/10.1007/s10641-013-0159-x.

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Abed, Riadh, Sunil Mehta, Aurelio José Figueredo, Sarah Aldridge, Hannah Balson, Caroline Meyer, and Robert Palmer. "Eating Disorders and Intrasexual Competition: Testing an Evolutionary Hypothesis among Young Women." Scientific World Journal 2012 (2012): 1–8. http://dx.doi.org/10.1100/2012/290813.

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The sexual competition hypothesis (SCH) contends that intense female intrasexual competition (ISC) is the ultimate cause of eating disorders. The SCH explains the phenomenon of the pursuit of thinness as an adaptation to ISC in the modern environment. It argues that eating disorders are pathological phenomena that arise from the mismatch between the modern environment and the inherited female adaptations for ISC. The present study has two aims. The first is to examine the relationship between disordered eating behavior (DEB) and ISC in a sample of female undergraduates. The second is to establish whether there is any relationship between disordered eating behavior and life history (LH) strategy. Participants completed a battery of questionnaires examining eating-related attitudes and behaviors, ISC, and LH strategy. A group of 206 female undergraduates were recruited. A structural equation model was constructed to analyze the data. ISC for mates was significantly associated with DEB, as predicted by the SCH. DEB was found to be predicted by fast LH strategy, which was only partially mediated by the SCH. The results of this study are supportive of the SCH and justify research on a clinical sample.

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Mehta, S., R. Abed, A. J. Figueredo, S. Aldridge, H. Balson, C. Meyer, and R. Palmer. "Eating disorders and intrasexual competition: Testing an evolutionary hypothesis among young women." European Psychiatry 26, S2 (March 2011): 709. http://dx.doi.org/10.1016/s0924-9338(11)72414-2.

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IntroductionCompeting theories on the aetiology of eating disorders originate from a diverse set of disciplines. One such discipline is Evolutionary Psychology which assumes that the human mind has been shaped by natural and sexual selection. Most evolutionary theories on eating disorders limit themselves to the causation of anorexia nervosa only. The Sexual Competition Hypothesis (SCH), based on the Darwinian theory of sexual selection, provides an explanatory framework for the whole spectrum of eating disorders. It contends that intense female intrasexual competition (ISC) is the ultimate cause of eating disorders. The SCH explains the phenomenon of the pursuit of thinness as an adaptation to ISC in the modern environment. It argues that eating disorders are pathological phenomena that arise from the mismatch between the modern environment and the inherited female adaptations for ISC.ObjectivesTo test predictions from a novel evolutionary hypothesis for eating disorders.Aimsi)To examine the relationship between disordered eating behaviour (DEB) and ISC in a sample of female undergraduates.ii)To establish whether there is any relationship between DEB and Life History (LH) strategy.MethodsA group of 206 female undergraduates were recruited. A structural equation model was constructed to analyse the data.ResultsISC for mates was significantly associated with DEB, as predicted by the SCH. DEB was found to be predicted by fast LH strategy, which was only partially mediated by the SCH.ConclusionsThe results of this study are supportive of the SCH and justify research on a clinical sample.

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Atema, Jelle. "Review of Sexual Selection and Chemical Communication in the Lobster, Homarus americanus." Canadian Journal of Fisheries and Aquatic Sciences 43, no. 11 (November 1, 1986): 2283–90. http://dx.doi.org/10.1139/f86-279.

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Field and laboratory observations have shown that female lobsters, Homarus americanus, are the active searching partner in courtship, choosing locally dominant males. The attractive features of the male are suspected to be intrasexual aggressive behavior and chemical cues. Size-based dominance is an important factor allowing males to secure a suitable mating shelter. In nature, male and female lobsters often approach and check shelters of other lobsters. This behavior may allow the animals to monitor the observed daily and seasonal changes in their physical and social environment. Premolt females approach the dominant male's shelter frequently in the weeks before the female's molt. Indirect evidence indicates that the female then "blows" a urine-related sex pheromone into the male shelter. One to several days before molting, a female enters the male shelter. Female intrasexual competition increases the premolt, but not the postmolt, cohabitation period. During cohabitation, males fan with their pleopods blowing a strong current through the shelter and into the environment. This chemical advertisement attracts other females, including future mating partners, to his shelter entrance. Females spent 1–2 wk in the male shelter. Mating takes place 30 min after the female molts. Another female may start cohabitation with the male immediately. In one 10-wk period a dominant male in the laboratory cohabited and mated with five females in sequence; females ignored a second male of equal size. Theoretically, by allowing a female to spend time in his shelter the male foregoes other mating opportunities, but this is balanced—and hence a stable strategy—by his protection of a vulnerable postmolt female who carries his offspring. Females must choose males who can protect them efficiently from prédation and, perhaps more importantly, from competing lobsters.

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Rucas, Stacey L., Michael Gurven, Hillard Kaplan, Jeff Winking, Steve Gangestad, and Maria Crespo. "Female intrasexual competition and reputational effects on attractiveness among the Tsimane of Bolivia." Evolution and Human Behavior 27, no. 1 (January 2006): 40–52. http://dx.doi.org/10.1016/j.evolhumbehav.2005.07.001.

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Lardy, Sophie, Dominique Allainé, and Aurélie Cohas. "Intrasexual competition and female dominance in a singular breeding mammal, the Alpine marmot." Animal Behaviour 86, no. 6 (December 2013): 1155–63. http://dx.doi.org/10.1016/j.anbehav.2013.09.017.

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Campbell, Anne. "Staying alive: Evolution, culture, and women's intrasexual aggression." Behavioral and Brain Sciences 22, no. 2 (April 1999): 203–14. http://dx.doi.org/10.1017/s0140525x99001818.

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Females' tendency to place a high value on protecting their own lives enhanced their reproductive success in the environment of evolutionary adaptation because infant survival depended more upon maternal than on paternal care and defence. The evolved mechanism by which the costs of aggression (and other forms of risk taking) are weighted more heavily for females may be a lower threshold for fear in situations which pose a direct threat of bodily injury. Females' concern with personal survival also has implications for sex differences in dominance hierarchies because the risks associated with hierarchy formation in nonbonded exogamous females are not offset by increased reproductive success. Hence among females, disputes do not carry implications for status with them as they do among males, but are chiefly connected with the acquisition and defence of scarce resources. Consequently, female competition is more likely to take the form of indirect aggression or low-level direct combat than among males. Under patriarchy, men have held the power to propagate images and attributions which are favourable to the continuance of their control. Women's aggression has been viewed as a gender-incongruent aberration or dismissed as evidence of irrationality. These cultural interpretations have “enhanced” evolutionarily based sex differences by a process of imposition which stigmatises the expression of aggression by females and causes women to offer exculpatory (rather than justificatory) accounts of their own aggression.

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Roberts, S. C. "The Evolution of Hornedness in Female Ruminants." Behaviour 133, no. 5-6 (1996): 399–442. http://dx.doi.org/10.1163/156853996x00521.

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AbstractFemales of many ruminant species possess horns or hornlike organs, but their precise function remains largely unclear. In this paper, four previous explanations for female hornedness are compared with a new hypothesis, the Female Competition Hypothesis, which suggests that horns initially evolved for reasons of intrasexual competition for resources with con-specifics, the level of competition being correlated with female group size. Each hypothesis is first reviewed and necessary predictions arising from each are generated. In order to test between these hypotheses, the incidence of female hornedness across the ruminants is then examined using a comparative method which takes account of the evolutionary history of each species, in order to control for effects of phylogenetic correlation. Group size and body size are found to be the only variables which predict hornedness successfully; however, when the influence of the other predicting variable is removed, only group size remains as a significant predictor. This analysis is found to support the Female Competition Hypothesis and is shown to be robust both in relation to adjustments in phylogenetic construction (e.g. the position of Aepyceros and Boocerus) and to intraspecific variation in horned condition (e.g. horned and hornless races of Oreotragus).

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Arnocky, Steven, Valentina Proietti, Erika L. Ruddick, Taylor-Rae Côté, Triana L. Ortiz, Gordon Hodson, and Justin M. Carré. "Aggression Toward Sexualized Women Is Mediated by Decreased Perceptions of Humanness." Psychological Science 30, no. 5 (March 28, 2019): 748–56. http://dx.doi.org/10.1177/0956797619836106.

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Researchers have argued that the regulation of female sexuality is a major catalyst for women’s intrasexual aggression. The present research examined whether women behave more aggressively toward a sexualized woman and whether this is explained by lower ratings of the target’s humanness. Results showed that women rated another woman lower on uniquely human personality traits when she was dressed in a sexualized (vs. conventional) manner. Lower humanness ratings subsequently predicted increased aggression toward her in a behavioral measure of aggression. This effect was moderated by trait intrasexual competitiveness; lower humanness ratings translated into more aggression, but only for women scoring relatively high on intrasexual competition. Follow-up studies revealed that the effect of sexualized appearance on perceived humanness was not due to the atypicality of the clothing in a university setting. The current project reveals a novel psychological mechanism through which interacting with a sexualized woman promotes aggressive behavior toward her.

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Stångberg, Josefine, Elina Immonen, Pilar Puimedon Moreno, and Elisabeth Bolund. "Experimentally induced intrasexual mating competition and sex‐specific evolution in female and male nematodes." Journal of Evolutionary Biology 33, no. 12 (October 2020): 1677–88. http://dx.doi.org/10.1111/jeb.13706.

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Thomas, Lisa K., and Andrea Manica. "Intrasexual competition and mate choice in assassin bugs with uniparental male and female care." Animal Behaviour 69, no. 2 (February 2005): 275–81. http://dx.doi.org/10.1016/j.anbehav.2004.03.009.

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Campbell, Anne. "The evolutionary psychology of women's aggression." Philosophical Transactions of the Royal Society B: Biological Sciences 368, no. 1631 (December 5, 2013): 20130078. http://dx.doi.org/10.1098/rstb.2013.0078.

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Evolutionary researchers have identified age, operational sex ratio and high variance in male resources as factors that intensify female competition. These are discussed in relation to escalated intrasexual competition for men and their resources between young women in deprived neighbourhoods. For these women, fighting is not seen as antithetical to cultural conceptions of femininity, and female weakness is disparaged. Nonetheless, even where competitive pressures are high, young women's aggression is less injurious and frequent than young men's. From an evolutionary perspective, I argue that the intensity of female aggression is constrained by the greater centrality of mothers, rather than fathers, to offspring survival. This selection pressure is realized psychologically through a lower threshold for fear among women. Neuropsychological evidence is not yet conclusive but suggests that women show heightened amygdala reactivity to threatening stimuli, may be better able to exert prefrontal cortical control over emotional behaviour and may consciously register fear more strongly via anterior cingulate activity. The impact of testosterone and oxytocin on the neural circuitry of emotion is also considered.

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Pradhan, Devaleena S., Madelyne C. Willis, Tessa K. Solomon-Lane, Kevin Thonkulpitak, and Matthew S. Grober. "Simultaneous courtship and parenting in males and sex role reversal in females of the haremic bluebanded goby, Lythrypnus dalli." Behaviour 152, no. 7-8 (2015): 917–40. http://dx.doi.org/10.1163/1568539x-00003262.

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While males typically compete for females, species with female biased sex ratios and/or large male investment in offspring care often exhibit reversed sex roles. Here we investigated, in a haremic fish species, the bluebanded goby,Lythrypnus dalli, the impact of male and female courtship behaviour on male reproductive success, measured as the total number of eggs in the nest and total number of developed eggs. Reproductive success was not associated with rates of male behaviour, such as parenting, approaching and courtship, but was associated with rates of female courtship. Consistent with predictions for a role-reversed reproductive strategy, only males demonstrated nest care and females exhibited high rates of courtship and intrasexual competition, such that alpha females interrupted courtship solicitations by beta females. Overall, these data are consistent with sex role reversal inL. dalliand show that the expression of male courtship behaviour does not interfere with paternal care.

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Tobias, Joseph A., Robert Montgomerie, and Bruce E. Lyon. "The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition." Philosophical Transactions of the Royal Society B: Biological Sciences 367, no. 1600 (August 19, 2012): 2274–93. http://dx.doi.org/10.1098/rstb.2011.0280.

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Ornaments, weapons and aggressive behaviours may evolve in female animals by mate choice and intrasexual competition for mating opportunities—the standard forms of sexual selection in males. However, a growing body of evidence suggests that selection tends to operate in different ways in males and females, with female traits more often mediating competition for ecological resources, rather than mate acquisition. Two main solutions have been proposed to accommodate this disparity. One is to expand the concept of sexual selection to include all mechanisms related to fecundity; another is to adopt an alternative conceptual framework—the theory of social selection—in which sexual selection is one component of a more general form of selection resulting from all social interactions. In this study, we summarize the history of the debate about female ornaments and weapons, and discuss potential resolutions. We review the components of fitness driving ornamentation in a wide range of systems, and show that selection often falls outside the limits of traditional sexual selection theory, particularly in females. We conclude that the evolution of these traits in both sexes is best understood within the unifying framework of social selection.

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Wormington, Jillian D., and Barney Luttbeg. "Disrupting information alters the behavioral response to a mutual signal trait in both sexes of Nicrophorus (Coleoptera: Silphidae) burying beetles." Behavioral Ecology 30, no. 4 (April 3, 2019): 960–67. http://dx.doi.org/10.1093/beheco/arz035.

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AbstractEffective signals transfer information in a way that enhances the fitness of the sender. Signal traits are often sexually dimorphic. However, in some species, males and females display similar signals, and these mutual signals are less often studied. Competition for resources occurs in both males and females, and mate choice is likely to occur whenever mates vary in quality and reproductive investment is high. Nicrophorus burying beetles compete intrasexually over the carrion resources on which they biparentally raise their young. Nicrophorus species also often have clypeal membranes which scale hyperallometrically with body size, exaggerating the apparent body size of larger individuals. To examine the potential signaling function of clypeal membranes, we examined the behavioral responses of male and female Nicrophorus orbicollis and Nicrophorus pustulatus burying beetles to same- and opposite-sex social partners which had their membranes painted black or clear. We found evidence that blocking the information in clypeal membranes affected intrasexual aggressive interactions for both sexes of both species. Blocking a female’s signal reduced the likelihood of mating attempts for male N. pustulatus, whereas blocking a male’s signal influenced female rejection behaviors in N. orbicollis. Our results show that males and females can experience similar selection pressures, and suggest that examining mutual signals in a broader range of systems will expand our understanding of evolutionary differences and similarities between the sexes.

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McLean, Claire A., Richard A. Bartle, Caroline M. Dong, Katrina J. Rankin, and Devi Stuart-Fox. "Divergent male and female mate preferences do not explain incipient speciation between lizard lineages." Current Zoology 66, no. 5 (March 12, 2020): 485–92. http://dx.doi.org/10.1093/cz/zoaa010.

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Abstract Diversification in sexual signals is often taken as evidence for the importance of sexual selection in speciation. However, in order for sexual selection to generate reproductive isolation between populations, both signals and mate preferences must diverge together. Furthermore, assortative mating may result from multiple behavioral mechanisms, including female mate preferences, male mate preferences, and male–male competition; yet their relative contributions are rarely evaluated. Here, we explored the role of mate preferences and male competitive ability as potential barriers to gene flow between 2 divergent lineages of the tawny dragon lizard, Ctenophorus decresii, which differ in male throat coloration. We found stronger behavioral barriers to pairings between southern lineage males and northern lineage females than between northern males and southern females, indicating incomplete and asymmetric behavioral isolating barriers. These results were driven by both male and female mate preferences rather than lineage differences in male competitive ability. Intrasexual selection is therefore unlikely to drive the outcome of secondary contact in C. decresii, despite its widely acknowledged importance in lizards. Our results are consistent with the emerging view that although both male and female mate preferences can diverge alongside sexual signals, speciation is rarely driven by divergent sexual selection alone.

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McDonald, Grant C., Lewis G. Spurgin, Eleanor A. Fairfield, David S. Richardson, and Tommaso Pizzari. "Differential female sociality is linked with the fine-scale structure of sexual interactions in replicate groups of red junglefowl, Gallus gallus." Proceedings of the Royal Society B: Biological Sciences 286, no. 1913 (October 16, 2019): 20191734. http://dx.doi.org/10.1098/rspb.2019.1734.

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Recent work indicates that social structure has extensive implications for patterns of sexual selection and sexual conflict. However, little is known about the individual variation in social behaviours linking social structure to sexual interactions. Here, we use network analysis of replicate polygynandrous groups of red junglefowl ( Gallus gallus ) to show that the association between social structure and sexual interactions is underpinned by differential female sociality. Sexual dynamics are largely explained by a core group of highly social, younger females, which are more fecund and more polyandrous, and thus associated with more intense postcopulatory competition for males. By contrast, less fecund females from older cohorts, which tend to be socially dominant, avoid male sexual attention by clustering together and perching on branches, and preferentially reproduce with dominant males by more exclusively associating and mating with them. Collectively, these results indicate that individual females occupy subtly different social niches and demonstrate that female sociality can be an important factor underpinning the landscape of intrasexual competition and the emergent structure of animal societies.

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López, Pilar, and José Martín. "Intersexual differences in chemosensory responses to selected lipids reveal different messages conveyed by femoral secretions of male Iberian rock lizards." Amphibia-Reptilia 29, no. 4 (2008): 572–78. http://dx.doi.org/10.1163/156853808786230479.

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AbstractThe effects of intrasexual selection (i.e., male-male competition) and intersexual selection (i.e., mate choice) may result on the evolution of different secondary sexual traits. We tested whether chemosensory responses of male and female Iberolacerta cyreni lizards to femoral secretion of conspecific males (a chemical sexual trait used in social behavior) were eliciting by different chemical traits. Tongue-flick essays showed that males and females had similar chemosensory responses to the femoral secretions of males, but males and females differed in the magnitude of their chemosensory responses to the different chemicals found in secretions. Moreover, responses to chemicals related to body size depended on the own body size of the responding male, but did not in females. These results might support that femoral secretions of males convey different messages for male or female I. cyreni lizards.

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Fisher, Maryanne L., and Cristina Candea. "You ain’t woman enough to take my man: Female intrasexual competition as portrayed in songs." Journal of Social, Evolutionary, and Cultural Psychology 6, no. 4 (December 2012): 480–93. http://dx.doi.org/10.1037/h0099238.

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Chu, Kevin, and Sharon Nieukirk. "Dorsal fin scars as indicators of age, sex, and social status in humpback whales (Megaptera novaeangliae)." Canadian Journal of Zoology 66, no. 2 (February 1, 1988): 416–20. http://dx.doi.org/10.1139/z88-059.

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We compared the number of linear marks and the shapes of dorsal fins of different classes of humpback whales during the breeding season. Male humpbacks tend to have more marks than females. Such marks are probably scars resulting from physical contact during intrasexual competition for mates. Not all males have marks; therefore, an unmarked adult humpback could be a male or a female. An adult with many marks is likely a male, however. Differences in the dorsal fins of principal and secondary escorts in large groups of competing males suggest that not all escorts have the same chance of attaining principal escort status. Therefore, male – male competitions in large groups should not necessarily be viewed as contests between equals. Principal escorts showed significantly more of some types of marks than did lone escorts of cows with calves, suggesting that not all lone escorts may retain their position if challenged.

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Nityananda, Vivek, and Rohini Balakrishnan. "Modeling the role of competition and cooperation in the evolution of katydid acoustic synchrony." Behavioral Ecology 20, no. 3 (2009): 484–89. http://dx.doi.org/10.1093/beheco/arp022.

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Abstract The precise timing of individual signals in response to those of signaling neighbors is seen in many animal species. Synchrony is the most striking of the resultant timing patterns. One of the best examples of acoustic synchrony is in katydid choruses where males produce chirps with a high degree of temporal overlap. Cooperative hypotheses that speculate on the evolutionary origins of acoustic synchrony include the preservation of the species-specific call pattern, reduced predation risks, and increased call intensity. An alternative suggestion is that synchrony evolved as an epiphenomenon of competition between males in response to a female preference for chirps that lead other chirps. Previous models investigating the evolutionary origins of synchrony focused only on intrasexual competitive interactions. We investigated both competitive and cooperative hypotheses for the evolution of synchrony in the katydid Mecopoda “Chirper” using physiologically and ecologically realistic simulation models incorporating the natural variation in call features, ecology, female preferences, and spacing patterns, specifically aggregation. We found that although a female preference for leading chirps enables synchronous males to have some selective advantage, it is the female preference for the increased intensity of aggregations of synchronous males that enables synchrony to evolve as an evolutionarily stable strategy.

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LaPlante, Lori Hosaka. "Female belly colour and bobbing behaviour advertise sexual receptivity in a pelagic-spawning coral reef fish." Behaviour 152, no. 6 (2015): 705–25. http://dx.doi.org/10.1163/1568539x-00003250.

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Female nuptial signals (FNSs) advertise reproductive state, individual quality, and are used in intrasexual competition. I explored whether pelagic-spawning pink-belly wrasse (Halichoeres margaritaceus) used red belly colouration and a unique bobbing behaviour as FNSs to advertise spawning readiness. I examined (i) if there was a temporal pattern in belly colour and incidence of bobbing, as each related to spawning; (ii) response of female belly colouration during male courtship behaviours; and (iii) pink belly area as it related to body area and bobbing rate. Temporal patterns were detected, females displayed ephemeral red belly colour and bobbing behaviour prior to spawning; females displaying red belly colouration elicited more courtship behaviour from males than females with white or pink belly colouration, and larger females displayed larger red belly areas. Benefits to advertising spawning readiness in pink-belly wrasse are discussed, including a reduction in mate-searching costs and potential for increased reproductive success through sex-change.

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Orbach, D. N., G. G. Rosenthal, and B. Würsig. "Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchus obscurus)." Canadian Journal of Zoology 93, no. 6 (June 2015): 503–7. http://dx.doi.org/10.1139/cjz-2015-0081.

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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.

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Schram, Thomas A., and Peter Andreas Heuch. "Male Mate Choice in a Natural Population of the Parasitic Copepod Lernaeocera Branchialis (Copepoda: Pennellidae)." Behaviour 133, no. 3-4 (1996): 221–39. http://dx.doi.org/10.1163/156853996x00125.

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AbstractVariations in age and sex structure of a natural population of the copepod Lernaeocera branchialis, parasitic on flounder, Platichthys flesus were examined in a 15-month study. Recent laboratory studies and literature on reproductive strategies indicate that male mate choice in this species should depend on the sex ratios of the parasite on its hosts, and on the age and mating status of females. Sex ratios suggested a strong intra-male competition for females. The ratio of chalimus 4 and virgin adult females (preferred stages) to adult males exceeded 1 female: 4 males on 50% of the hosts. In four out of the six sampling periods, more than 50% of hosts harboured more adult males than the total number of females. The males preference for the different female stages was estimated from the number of precopula and copula associations. The data were fitted to a logistic regression model. At most sex ratios, males preferred chalimus 4 and virgin adult females, and discriminated against younger stages. Mated females were about as attractive as the youngest larval stages at female-biased sex ratios, but they were chosen more frequently at strongly male-biased sex ratios. Most adult L. branchialis females had copulated more than once, and some had accommodated at least 5 ejaculates in the their sperm storage organs. The patterns of mate guarding and potential for sperm competition strongly suggest that L. branchialis males take the intrasexual competition into account when choosing mates. On this basis, they minimize guarding time and maximize the possibility of paternity.

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Borau, Sylvie, and Jean-François Bonnefon. "The Imaginary Intrasexual Competition: Advertisements Featuring Provocative Female Models Trigger Women to Engage in Indirect Aggression." Journal of Business Ethics 157, no. 1 (July 20, 2017): 45–63. http://dx.doi.org/10.1007/s10551-017-3643-y.

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Cook, D. "Sexual Selection in Dung Beetles .2. Female Fecundity as an Estimate of Male Reproductive Success in Relation to Horn Size, and Alternative Behavioral Strategies in Onthophagus-Binodis Thunberg (Scarabaeidae, Onthophagini)." Australian Journal of Zoology 36, no. 5 (1988): 521. http://dx.doi.org/10.1071/zo9880521.

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One component of the reproductive success (fitness) of Onthophagus binodis Thunberg males was estimated by the number of offspring their mate produced relative to male horn and body size. O. binodis males consist of large horned and small hornless morphs. Female fecundity was significantly increased when reproducing with: (1) large horned males compared with small hornless males; (2) the horned morph compared with the hornless morph of males with similar body size. Horned males cooperating with females invest a considerable effort in providing each egg with dung. Hornless males do not appear to assist females after mating. Alternative male mating strategies are predicted under intense intrasexual competition. As hornless O. binodis males persist in large numbers alongside cooperative, mate guarding horned males, selection should favour alternative tactics by hornless males to gain reproductive opportunities.

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Clapham, Phillip J. "Age at attainment of sexual maturity in humpback whales, Megaptera novaeangliae." Canadian Journal of Zoology 70, no. 7 (July 1, 1992): 1470–72. http://dx.doi.org/10.1139/z92-202.

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Twelve female humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine produced first-observed calves at ages ranging from 5 to 7 years. These data confirm that most females of this species attain sexual maturity at an average age of approximately 5 years. Observations in the West Indies of two males, aged 6 and 7 years, engaged in breeding-related behavior that is characteristic of mature animals suggests that males attain sexual maturity within a similar range of ages to females, although they may not be able to successfully engage in intrasexual competition until later in life. These data imply that the examination of ear plugs to determine the age of dead humpback whales should be based upon an assumed annual growth rate of two growth layer groups, not one.

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Stutchbury, Bridget J., and Raleigh J. Robertson. "Signaling Subordinate and Female Status: Two Hypotheses for the Adaptive Significance of Subadult Plumage in Female Tree Swallows." Auk 104, no. 4 (October 1, 1987): 717–23. http://dx.doi.org/10.1093/auk/104.4.717.

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Abstract Delayed plumage maturation in males is relatively common among North American passerines, but the Tree Swallow (Tachycineta bicolor) is one of few species in which 1-yr-old females have a distinct subadult plumage. Although they are reproductively mature, most subadult females do not breed in their first year because of intense intrasexual competition for nesting sites. Early in the season, subadult female floaters explore for recently vacated nest sites. The subadult plumage of young females could be adaptive by communicating their low threat to residents, thereby decreasing the cost of this exploration. To determine whether resident aggression depends on intruder color, we observed live intrusions and conducted model presentations. When the resident female was out of sight or did not respond to intruders, resident males were significantly less aggressive toward subadult females than toward adult intruders in both the nest-building/egg-laying and incubation stages. Early in the season, resident females were equally aggressive toward subadult female and adult intruders. When presented simultaneously with adult and subadult female models, resident males were always more aggressive toward the adult model, whereas females were aggressive toward either model. We propose two hypotheses for the adaptive significance of subadult plumage in female Tree Swallows: subordinance signaling and sex signaling. Our results suggest that subadult females may reduce resident aggression by signaling their female status to resident males, rather than by signaling their subordinate status to resident females.

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Duncan, Patrick, Vincent Boy, and Anne-Marie Monard. "The Proximate Mechanisms of Natal Dispersal in Female Horses." Behaviour 133, no. 13-14 (1996): 1095–124. http://dx.doi.org/10.1163/156853996x00611.

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AbstractThe aim of this study was to investigate proximate mechanisms of natal dispersal by female horses, Equus caballus (i.e. proximate causes and the factors influencing the timing), and to test predictions from two functional hypotheses: the intrasexual competition hypothesis, and inbreeding avoidance. The data concerned 40 individuals born between 1974-1985 in a closely monitored herd which developed a natural social structure during this period. All the females dispersed from their natal groups; none became solitary; 80% transferred to existing harems, the others formed new groups with bachelor stallions. Abduction by stallions affected only a quarter of the females whose transfers were observed. The results of this study do not support the hypothesis that a function of natal dispersal is to reduce intrasexual competition. The young females were not expelled by resident females of their natal groups, and did not, as a rule, experience increased aggression from these females before emigration. Their social bonds with members of their natal groups showed no progressive weakening prior to departure, and there was no gradual strengthening of bonds with individuals in the groups to which they transferred. There was no evidence for reproductive competition between the young females and resident mares of their natal groups, since the young females always refused the sexual approaches by males of these groups. Finally, age at dispersal did not decrease with the number of resident females in the groups they left. In contrast, as predicted by the inbreeding avoidance hypothesis, the primary cause of dispersal appeared to be sexual attraction to unfamiliar males. When in oestrus and before dispersing, the young females accepted matings only with males of other groups in spite of frequent sexual approaches by males of their natal groups (normally close relatives). In addition, none dispersed before first oestrus, and most did so during an oestrous period, at or before the conception of their first foal. The mothers of most young females interposed themselves when close kin males of the natal group approached their daughters sexually; this could contribute to the avoidance of close inbreeding. Among the other factors examined, some did not influence dispersal of the young females : they experienced low levels of aggression by adult stallions of their natal groups, particularly at the time of departure; their weight and body condition had no significant effects on leaving age nor did their mother's rank, the number of siblings, or the birth of another. In contrast, as the number of groups and the breeding sex ratio increased, dispersal age declined, occurring at a median age of 23 months (range 12-42 months) in the later years, when the herd had developed a natural social system.

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Leitão, Ana V., Michelle L. Hall, and Raoul A. Mulder. "Female and male plumage color is linked to parental quality, pairing, and extrapair mating in a tropical passerine." Behavioral Ecology 32, no. 3 (February 16, 2021): 452–63. http://dx.doi.org/10.1093/beheco/araa154.

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Abstract Sexual selection has been proposed to drive the evolution of elaborate phenotypic traits in males, which often confer success in competition or mating. However, in many species, both males and females display such traits. Studies examining how selection acts on both sexes are scarce. In this study, we investigated whether plumage ornamentation is sexually selected in females and males lovely fairy-wren Malurus amabilis, a cooperatively breeding songbird. We found that female and male plumage color was correlated with parental quality but not with individual quality or survival. We also found evidence of positive assortative mating based on plumage color. Microsatellite analyses of paternity indicated that the lovely fairy-wren has high levels of extrapair paternity (EPP), with 53% of offspring (in 58% of broods of 57% of females) resulting from extrapair (EP) mating. Female and male plumage color did not predict reproductive success or the proportion of EP offspring in their own nest, but less colorful males obtained higher EPP when paired with more colorful females and gained overall higher total paternity (own nest and other nests). We argue that plumage color may be under sex-specific selection, highlighting the importance of looking at both sexes in studies of sexual selection and ornament evolution. The current findings together with the previous study suggest that plumage color in female and male lovely fairy-wrens appears to be an honest signal relevant in both intrasexual and intersexual competition contexts.

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Otterbring, Tobias, Christine Ringler, Nancy J. Sirianni, and Anders Gustafsson. "The Abercrombie & Fitch Effect: The Impact of Physical Dominance on Male Customers' Status-Signaling Consumption." Journal of Marketing Research 55, no. 1 (February 2018): 69–79. http://dx.doi.org/10.1509/jmr.15.0247.

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Consumer lay theory suggests that women will spend more money than men in the presence of a physically dominant male employee, whereas theories of intrasexual competition from evolutionary psychology predict the opposite outcome. A retail field study demonstrates that male customers spend more money and purchase more expensive products than their female counterparts in the presence (vs. absence) of a physically dominant male employee. This effect has a more powerful impact on male customers who lack bodily markers of dominance (shorter stature or measures linked to lower levels of testosterone). When confronted with other physically dominant (vs. nondominant) men, these male customers are particularly prone to signal status through price or logo size. Their elevated feelings of intrasexual (male-to-male) competitiveness drive them to spend more money on status-signaling, but not functional, products and to prefer and draw larger brand logos. Because pictorial exposure is sufficient for the effect to occur, these findings are not limited to in-store interactions with dominant male employees but have broad implications for marketing and advertising.

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Swierk, Lindsey, and Tracy Langkilde. "Size-assortative mating in explosive breeders: a case study of adaptive male mate choice in anurans." Behaviour 158, no. 10 (May 26, 2021): 849–68. http://dx.doi.org/10.1163/1568539x-bja10098.

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Abstract Exploration of size-assortative mating (SAM) in animals has led to a near consensus that it arises through constraints in choice, such as preference for large females combined with a large male advantage during intrasexual competition. Although such ‘apparent’ SAM is well explored, whether SAM arises because of specific preferences for size-matched mates has been less thoroughly considered. We tested for ‘preference-based’ SAM in an explosively breeding frog (Rana sylvatica), quantifying how male and female sizes affected fertilization and if males preferred size-matched females. We found that size mismatch severely reduced fertilization. Furthermore, males preferred size-matched, not larger, females in mate choice trials. Because males that mated with much larger females fertilized fewer eggs overall than they would have with size-matched females, male preference for size-matched females may be adaptive. Our results expand understanding of the mechanisms underlying SAM, suggesting that multiple mechanisms may simultaneously cause size-assortative mating patterns to emerge.

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Bajer, Katalin, Orsolya Molnár, János Török, and Gábor Herczeg. "Ultraviolet nuptial colour determines fight success in male European green lizards ( Lacerta viridis )." Biology Letters 7, no. 6 (June 29, 2011): 866–68. http://dx.doi.org/10.1098/rsbl.2011.0520.

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Animal communication through colour signals is a central theme in sexual selection. Structural colours can be just as costly and honest signals as pigment-based colours. Ultraviolet (UV) is a structural colour that can be important both in intrasexual competition and mate choice. However, it is still unknown if a UV signal alone can determine the outcome of male–male fights. European green lizard ( Lacerta viridis ) males develop a nuptial throat coloration with a strong UV component. Among males differing only in their manipulated UV colour, females prefer males with higher UV. Here, we experimentally decreased the UV coloration of randomly chosen males from otherwise similar male pairs to test the hypothesis that a difference in UV colour alone can affect fight success during male–male competition. Our results fully supported the hypotheses: in almost 90 per cent of the contests the male with reduced UV lost the fight. Our results show that UV can be an important signal, affecting both female mate choice and determining male fight success.

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Magliocca, Florence, Sophie Quérouil, and Annie Gautier-Hion. "Grouping patterns, reproduction, and dispersal in a population of sitatungas (Tragelaphus spekei gratus)." Canadian Journal of Zoology 80, no. 2 (February 1, 2002): 245–50. http://dx.doi.org/10.1139/z01-224.

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A population of sitatungas (Tragelaphus spekei gratus) living in a forest swamp clearing, Maya Nord, in the Republic of Congo was studied over 3½ years and its grouping patterns and population dynamics were analysed. The sitatungas in this clearing formed a stable group, which remained in residence. The group (1636 individuals) functioned like a harem. As a result of intrasexual competition, all the males and some of the females born at Maya left the group before reaching sexual maturity. We hypothesize that this large grouping resulted from the development of a tendency for females to be gregarious for reasons related to food availability. This tendency, combined with an aseasonal pattern of reproduction, favours direct monopolization of females by one male. Social and mating strategies observed at Maya fit the model of "female-defence polygyny" (Emlen and Oring). Our results provide an argument in favour of relating food availability and grouping patterns, and underline the plasticity of social organization and mating strategies in sitatungas.

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Journal articles on the topic 'Female intrasexual competition'

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