Correlation between male song repertoire, extra-pair paternity and offspring
survival in the great reed warbler
Hasselquist, D. Bensch, S. & von Schantz, T.
Nature 381: 229-232. 1996.
In many birds, females copulate with males other
than their social mate and this result in extra-pair fertilizations (EPF).
It is still unknown, however, why females seek EPF. In one study, males
that accounted for most EPFs had higher survival, but neither the characteristics
revealing male quality nor the benefits accruing to females selecting attractive
males were identified. Great reed warblers Acrocephalus arundinaceus are
socially polygynous and females seem to base their mate choice on territory
quality and song repertoire size; both these parameters predict harem size
and reproductive success. By DNA-fingerprinting of 678 young, we demonstrate
that female great reed warblers obtain EPFs from neighbouring males with
larger song repertoires than their social mate. In addition, the relative
post-fledging survival of offspring was positively correlated with their
genetical fathers' song repertoire size. These data support the hypothesis
that females, by engaging in extra-pair fertilizations, seek genetic benefits
for their offspring.