https://popups.lib.uliege.be/2984-0317/index.php?id=586 Entrées d’index fr 0 https://popups.lib.uliege.be/2984-0317/index.php?id=883 Sexual selection theory suggests that variation in individual reproductive success results from mechanisms of competition and choice of the sexual partner. Male competition involves risks from fights and mobility in order to find female partners. Primate male sexual activity seems sometimes related to hierarchical rank, but this does not necessarily represent an increased reproductive success. Dominance might be one tactic among other, leading to increased reproductive success in given conditions. Males also form occasional coalitions granting them access to sexual partners despite a low hierarchical status. Male competitive tactics vary depending on age, social rank, and various demographic variables. The choice of a specific strategy and its efficiency are influenced by female preferences. Primate females can choose their mates either directly, by initiating or rejecting copulation, or indirectly, by accepting or rejecting a male into their social group, or by joining themselves a group rather than another. Criteria females use to choose their mate are unknown, but evidences suggest that their choice is related to increased protection against other males' aggressive behaviour and potential infanticide, as well as to inbreeding avoidance. Female competition for mates and male choice of female partners are also present in primates, both sexes competing at relative rates for qualitative as well as for quantitative aspects. Finally, observation of stable preferences between individuals, even in polygamous species, underlines the value of studying long-term relationships in primates. La théorie de sélection sexuelle explique la variation du succès reproducteur entre individus d'un même sexe par les mécanismes de compétition et de choix du partenaire sexuel. La compétition des mâles pour l'accès aux femelles comporte les risques liés aux combats et à la nécessité de se déplacer pour trouver les partenaires. Succès reproducteur et rang hiérarchique sont parfois liés chez le primate mâle, mais ce n'est pas toujours le cas. La dominance relative ne serait une tactique rentable que dans certaines conditions. Les mâles forment parfois des coalitions qui leur permettent de compenser leur désavantage hiérarchique. Ils peuvent utiliser des tactiques de compétition variées selon leur âge, leur rang, ou le profil démographique particulier de la population. Le choix de la stratégie et son efficacité sont influencés par les préférences des femelles. Les femelles primates peuvent choisir leurs partenaires directement en suscitant ou en rejetant les copulations. Elles peuvent aussi exercer indirectement leur choix, en favorisant ou en refusant l'intégration d'un mâle dans leur groupe social ou en choisissant elles-mêmes de rejoindre un groupe plutôt qu'un autre. On ignore quels sont leurs critères de choix, mais les indications dont on dispose suggèrent que ce choix est lié à un souci de protection contre l'agression des autres mâles et contre l'infanticide, et avec l'évitement de la consanguinité. La compétition des femelles pour les mâles et la préférence des mâles pour certaines partenaires sont également présentes chez les primates, chacun des deux sexes se battant à des degrés divers pour des aspects qualitatifs et quantitatifs de reproduction. Enfin, la présence de préférences interindividuelles stables, même chez les espèces polygames, souligne l'importance certaine de l'étude des relations à long terme chez les primates. Tue, 30 Jan 2024 15:29:51 +0100 Tue, 30 Jan 2024 15:30:01 +0100 https://popups.lib.uliege.be/2984-0317/index.php?id=883 https://popups.lib.uliege.be/2984-0317/index.php?id=573 It could be misleading to consider that the social behaviour of newts and salamanders is simple and can be generalized. Indeed, individuals are faced with external and internal conditions which are extremely variable. In response to these factors, they may respond in a particular way. The behavioural variations, called alternative tactics, allow individuals to improve their fitness, i.e. to ensure the survival of their genes. They can be exhibited in reaction to a large range of factors such as the mere presence or density of competitors, the operational sex-ratio, the behaviour and kinship of the other individuals, the abiotic characteristics of the environment, the experience of the individuals involved. These alternative tactics are favoured in urodeles. Indeed, although the main process of fertilization is internal, they breed by means of a spermatophore deposited in the external environment. Each species of newts and salamanders exhibits specific behavioural patterns as they developed and evolved in particular environments which have exerted selective pressures on the individuals and in this way on the species. As a consequence, the understanding of patterns of behaviour requires that we know the environment in which they appeared. The main occurrence of parental care and territoriality in terrestrial environments may be explained by the features of these habitats in which eggs could not survive without protection and in which adults may defend areas of particular interest and communicate by means of pheromones. All of these characteristics show that we have to study the behaviour of individuals of different species under several conditions. Without such an analysis, it would be difficult to understand biodiversity. Fri, 26 Jan 2024 14:05:49 +0100 Fri, 26 Jan 2024 14:09:36 +0100 https://popups.lib.uliege.be/2984-0317/index.php?id=573