Search results for "Competitive behavior"
showing 10 items of 100 documents
Hormonal and emotional responses to competition using a dyadic approach: Basal testosterone predicts emotional state after a defeat.
2019
The present study analyzes the testosterone (T), cortisol (C) and emotional response in competitive interactions between dyads, as well as the relationship between basal T and the emotional response. Seventy-two men and women (36 dyads) participated in same-sex dyads in a face-to-face laboratory competition, and thirty-two men and women (16 dyads) carried out the same task in a non-competitive condition. Salivary samples (5 ml of saliva, plastic vials) were provided at three time points (baseline, task, and post-task), and subsequently T (pg/ml) and C (nmol/L) concentrations were measured using ELISA method. Participants completed self-reported measures of emotional valence, emotional arous…
Sexual selection drives asymmetric introgression in wall lizards.
2015
Hybridisation is increasingly recognised as an important cause of diversification and adaptation. Here, we show how divergence in male secondary sexual characters between two lineages of the common wall lizard (Podarcis muralis) gives rise to strong asymmetries in male competitive ability and mating success, resulting in asymmetric hybridisation upon secondary contact. Combined with no negative effects of hybridisation on survival or reproductive characters in F1-hybrids, these results suggest that introgression should be asymmetric, resulting in the displacement of sexual characters of the sub-dominant lineage. This prediction was confirmed in two types of secondary contact, across a natur…
The Impact of World and European Football Cups on Stroke in the Population of Dijon, France: A Longitudinal Study from 1986 to 2006
2013
Background: Acute stress may trigger vascular events. We aimed to investigate whether important football competitions involving the French football team increased the occurrence of stroke. Methods: We retrospectively retrieved data of fatal and nonfatal stroke during 4 World Football Cups (1986, 1998, 2002, and 2006) and 4 European Championships (1992, 1996, 2000, and 2004), based on data from the population-based Stroke Registry of Dijon, France. One period of exposure was analyzed: the period of competition extended to 15 days before and after the competitions. The number of strokes was compared between exposed and unexposed corresponding periods of preceding and following years using Poi…
Conflict between co-occurring manipulative parasites? An experimental study of the joint influence of two acanthocephalan parasites on the behaviour …
2000
When two parasite species are manipulators and have different definitive hosts, there is a potential for conflict between them. Selection may then exist for either avoiding hosts infected with conflicting parasites, or for hijacking, i.e. competitive processes to gain control of the intermediate host. The evidence for both phenomena depends largely on the study of the relative competitive abilities of parasites within their common intermediate host. We studied the effects of simultaneous infection by a fish acanthocephalan parasite, Pomphorhynchus laevis, and a bird acanthocephalan parasite, Polymorphus minutus, on the behaviour of their common intermediate host, the amphipod Gammarus pulex…
Priority versus Brute Force: When Should Males Begin Guarding Resources?
2004
When should males begin guarding a resource when both resources and guarders vary in quality? This general problem applies, for example, to migrant birds occupying territories in the spring and to precopula in crustaceans where males grab females before they molt and become receptive. Previous work has produced conflicting predictions. Theory on migrant birds predicts that the strongest competitors should often arrive first, whereas some models of mate guarding have predicted that the strongest competitors wait and then simply usurp a female from a weaker competitor. We build a general model of resource guarding that allows varying the ease with which takeovers occur. The model is phrased i…
THE INTENSITY OF SEXUAL SELECTION PREDICTS WEAPON SIZE IN MALE BOVIDS
2007
As a classical example of a sexually selected trait, the horns of male bovids offer a prime opportunity to identify predictors of the intensity of sexual selection. Here I use the comparative method to quantify sexual and natural selection pressures behind interspecific variation in horn length. I show that male horn length depends on factors proposed to affect the mean mate number per mating male, correlating positively with group size and negatively with male territoriality. This suggests that whereas group size increases the opportunity for sexual selection, territoriality reduces it because territorial males are unable to follow and monopolize female groups as effectively as males in no…
Sexual selection, antennae length and the mating advantage of large males in Asellus aquaticus
2003
In crustacean species with precopulatory mate-guarding, sexual size dimorphism has most often been regarded as the consequence of a large male advantage in contest competition for access to females. However, large body size in males may also be favoured indirectly through scramble competition. This might partly be the case if the actual target of selection is a morphological character, closely correlated with body size, involved in the detection of receptive females. We studied sexual selection on body size and antennae length in natural populations of Asellus aquaticus, an isopod species with precopulatory mate guarding. In this species, males are larger than females and male pairing succe…
Strategic adjustments in sperm production within and between two island populations of house mice
2012
Sperm production is physiologically costly. Consequently, males are expected to be prudent in their sperm production, and tailor their expenditure according to prevailing social conditions. Differences in sperm production have been found across island populations of house mice that differ in the level of selection from sperm competition. Here, we determined the extent to which these differences represent phenotypic plasticity and/or population divergence in sperm production. We sourced individuals from two populations at the extreme levels of sperm competition, and raised them under common-garden conditions while manipulating the social experience of developing males. Males from the high-sp…
Costs of coexistence along a gradient of competitor densities: an experiment with arvicoline rodents
2006
Summary 1 Costs of coexistence for species with indirect resource competition usually increase monotonically with competitor numbers. Very little is known though about the shape of the cost function for species with direct interference competition. 2 Here we report the results of an experiment with two vole species in artificial coexistence in large enclosures, where density of the dominant competitor species (Microtus agrestis) was manipulated. Experimental populations of the subordinate vole species (Clethrionomys glareolus) were composed of same aged individuals to study distribution of costs of coexistence with a dominant species within an age-cohort. 3 Survival and space use decreased …
Goal orientation profile differences on perceived motivational climate, perceived peer relationships, and motivation-related responses of youth athle…
2006
The aims of this study were twofold: (a) to determine if dispositional achievement goal orientation profiles that are reported in the literature would be observed in a sample of youth athletes, and (b) to examine potential achievement goal orientation profile differences on perceptions of the motivational climate, perceptions of peer relationships, and motivation-related responses. Male soccer players (n=223) aged 9-12 years (mean=10.9, s=0.6) completed a multi-section questionnaire containing assessments of dispositional goal (task, ego) orientations, the perceived task- and ego-involving features of the motivational climate, perceived peer acceptance and friendship quality (positive frien…