FEMALE ZEBRA FINCHES CHOOSE EXTRA-PAIR COPULATIONS WITH GENETICALLY ATTRACTIVE MALES

One way that sexual selection for genetic benefits could operate in monogamous species is through female choice during extra-pair copulations (EPCS). EPCS are common in monogamous species, and field studies are consistent with the hypothesis of females choosing genetically attractive males for EPCS. Here I show that female zebra finches actively solicit and perform EPCS with males that are more attractive than their mates. Attractive males have higher song rates, have sons with higher song rates, and fledge heavier offspring. This provides a mechanism for sexual selection in monogamous species, and is consistent with `good genes' models of sexual selection.