Extra-pair young better perform than within-pair young in the Alpine marmot [Les jeunes hors couple sont meilleurs que les jeunes du couple chez la marmotte alpine].

Résumé

The alpine marmot is a socially monogamous rodent exhibiting a high rate of extra-pair paternity. We investigate whether females gain genetic benefits from extra-pair paternity (EPP) and what kind of genetic benefits they can gain. In precious analyses, we have shown that &) EPP occurs when the social partner is genetically very similar or very dissimilar to the female and that 2) extra-pair males are heterozygous and likely less genetically similar to the female than cuckooed males. These results seem to support the genetic compatibility hypothesis. However, a crucial test of this hypothesis is to investigate whether extra-pair young, expected to have a more compatible genome, have better performance than within-pair young. Here, we use capture-recapture methods to compare the survival and the probability to access to dominance (to reproduction) of extra-pair and within-pair young. Using a long-term database, we show that extra-pair young better survive until sexual maturity (two-years old) but not thereafter and tend to have a higher access to dominance than within-pair young. These results suggest that female alpine marmot probably gain genetic benefits through extra-pair copulation by producing more compatible young.