The genetic similarity between pair members influences the frequency of extrapair paternity in alpine marmots [La similitude génétique entre les membres du couple influe sur la fréquence de la paternité extrapair chez des marmottes alpines].

Résumé

Extrapair paternity is widespread in birds and mammals. In particular, the alpine marmot, has a high frequency of extrapair paternity that seems to be explained by the genetic compatibility hypothesis. We investigated whether the number and proportion of extra pair young depend on the(individual genetic diversity) of the social male, or on the genetic similarity between themale and his mate (relatedness). Both the number and the proportion of extrapair young increasedboth high similarity and dissimilarity between the social pair. In combination with previous results,study suggests that patterns of extrapair paternity in alpine marmots can best be explained by the genetic compatibility hypothesis, and more precisely its optimal outbreeding variant. Our results indeed suggest that extrapair paternity is amechanism to avoid both in- an dout breeding depression. We discussproximal mechanisms may be involved in extrapair paternity in this species.