Reproduktion und Paarungssystem bei Alpenmurmeltieren (Marmota marmota) [Reproduction et système d’appariement chez la marmotte alpine].

Résumé

Alpine marmots mature after their second hibernation but not all members of a family group reproduce successfully. Copulations could be observed between all females and males within a group. Closely related animals mate together, often resulting in close inbreeding, but apparently without any negative consequences. Only dominant females produce weaned young, which could be sired by several males, but mostly by the dominant one. Dominant animals suppress reproduction in subordinates by initiating agonistic interactions, which affect elevated levels of glucocorticoids ("stress hormones") in the blood of suppressed animals. In contrast to feamles, reproductive suppression in males is incomplete and predominantly sons of the dominant male may have some direct reproductive success. In groups with several subordinate females dominant females could be less reproductive. Apart from this intrasexual suppression males are able to prevent dominant females from reproduction when they take over a territory after the mating period. Hence, beside various benefits of sociality in Alpine marmots there are also costs, e.g. reproductive failures, caused by other group members.