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Mating Competition (mating + competition)
Selected AbstractsCountries with fewer males have more violent crime: marriage markets and mating aggressionAGGRESSIVE BEHAVIOR, Issue 1 2009Nigel Barber Abstract Violent crimes (murders, rapes, and assaults) are substantially higher in countries with a relative scarcity of men according to research using INTERPOL data [Barber, 2000a]. This is a paradox given that males are more criminally violent and likely reflects increased direct mating competition. The present research sought to confirm and extend Barber's [2000a] finding, using murder data from the United Nations and homicides from World Health Organization that are of higher quality than the INTERPOL data, and using more rigorous controls. In addition to level of economic development, control variables included, income inequality, urbanization, population density, the number of police, and whether the country was a major center of illegal drug trafficking. Regression analyses with all controls found that killings in both data sets increased with declines in the male proportion of the population. The findings are discussed in terms of direct reproductive competition and alternative explanations are considered. Aggr. Behav. 35:49,56, 2009. © 2008 Wiley-Liss, Inc. [source] Why is violent crime so common in the Americas?AGGRESSIVE BEHAVIOR, Issue 5 2006Nigel BarberArticle first published online: 11 JUL 200 Abstract Violent crimes, including murders, rapes, and assaults are substantially higher in the Americas than other regions of the world. This study investigated the role of single parenthood ratios in accounting for this regional variation in violent crime of 39 countries using INTERPOL data. It pitted the prediction of parental investment (calling for a delayed relationship between single parenthood and crime) against a mating aggression hypothesis that predicted a contemporaneous effect. Regression analyses found that current single parenthood ratios were strongly and consistently predictive of violent crimes whereas single parenthood ratios 18 years earlier were not and this conclusion remained following controls for income inequality and the population sex ratio. The results indicate that the regional difference in violent crime is best explained in terms of mating competition rather than reduced parental investment. Aggr. Behav. 32:1,9, 2006. © 2006 Wiley-Liss, Inc. [source] Seasonal sex role changes in the blenniid Petroscirtes breviceps, a nest brooder with paternal careJOURNAL OF FISH BIOLOGY, Issue 1 2006J. Shibata The plasticity of the sex roles in the blenniid fish Petroscirtes breviceps, a nest brooder with exclusive paternal care, was studied throughout an 8 month breeding season. Males performed most courtships early and late in the breeding season, whereas females performed most in the middle of the season. These results indicated that the sex of individuals initiating courtship changed seasonally, with courtship role reversal in the middle of the season. Intrasexual aggression in both sexes occurred much more frequently in mid-season than in the early and late seasons. Males frequently fought when available nest sites were limited, regardless of the presence of females, suggesting that males competed for nests in order to qualify to mate (resource competition). In contrast, courting females fought only in mid-season, when females' relative success in entering nests decreased, indicating that females competed for limited mating opportunities (mating competition). The reversed courtship roles and female mating competition in mid-season suggested that the sex roles in P. breviceps changed seasonally from the conventional roles to reversed roles and back again during one breeding season. This study provides the first empirical evidence of multiple changes in the sex roles of animals within a breeding season. [source] Genetic monogamy despite social promiscuity in the pot-bellied seahorse (Hippocampus abdominalis)MOLECULAR ECOLOGY, Issue 11 2007A. B. WILSON Abstract Sexual selection theory predicts a positive correlation between relative parental investment and mate choice. In syngnathid fishes (seahorses and pipefish), males brood offspring in specialized brooding structures. While female-female mating competition has been demonstrated in some pipefishes, all seahorses (genus Hippocampus) studied to date have been found to have conventional sex roles with greater male,male competition for access to mates despite possessing the most complex brood structures in the family. Although multiple mating is common in pipefish, seahorses are again exceptional, exhibiting strict genetic monogamy. Both demographic and behavioural explanations have been offered to explain the lack of multiple mating in seahorse species, but these hypotheses have not yet been explicitly addressed. We investigated mating systems and brood parentage of the pot-bellied seahorse, Hippocampus abdominalis, a temperate-water species that is socially promiscuous with conventional sex roles in laboratory populations. We observed promiscuous courtship behaviour and sex-role reversal in high density, female-biased field populations of H. abdominalis. We hypothesize that sex roles are plastic in H. abdominalis, depending on local population density and sex ratio. Despite promiscuous courtship behaviour, all assayed male seahorses were genetically monogamous in both laboratory and wild populations. Physiological limitations associated with embryo incubation may explain the absence of multiple mating in seahorses and may have played an important role in the development of the unique reproductive behaviour typical in these species. [source] Intra-community coalitionary lethal attack of an adult male southern muriqui (Brachyteles arachnoides)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2009M.G. Talebi Abstract We report on the first evidence of intra-community coalitionary lethal aggression in muriquis (Brachyteles). The event occurred in southern muriquis (Brachyteles arachnoides) during a long-term study (>15 years) of two social groups inhabiting mostly pristine Atlantic forest habitat in the Parque Estadual Carlos Botelho, southern São Paulo State, Brazil. The attack took place deep in the core area of the Group Caetê home range. Tense agonistic behaviors and vocalizations preceded the lethal coalitionary attack, and the tension increased over a 36,48,hr period. One adult female and two unidentified individuals also took part in a coalition led by six adult males. The members of the coalition collectively approached, embraced, immobilized and repeatedly bit the entire body of an adult male, resulting in severe bleeding injuries and the victim's death in less than 1,hr after the attack commenced. Combined ecological, behavioral and spatial data related to the event indicate that this was an intra-community attack and suggest social tensions related to mating competition as the proximate trigger of the coalitionary killing. The attack resembled those reported for chimpanzees, with clear numeric superiority and a low risk of injury to aggressors, resulting in the death of a lone conspecific victim. This observation (n=1) is suggestive of a capacity for escalated aggression in muriquis and reinforces arguments for the potential adaptive significance of intra-community aggression in male philopatric societies, as reported for spider monkeys and chimpanzees. These characteristics challenge the view of the muriquis as a peaceful primate and support the general hypothesis that imbalances of power contribute to intra-specific killing in primates, such as chimpanzees and humans. Am. J. Primatol. 71:860,867, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||