Female choice for genetic complementarity in birds: a review.

Data from avian species have played a prominent role in developing and testing theories of female mate choice. One of the most prominent models of sexual selection, the "good genes" model, emphasizes the indirect benefits of female preferences for male ornaments as indicators of a potential sire's additive genetic quality. However, there is growing interest in non-additive sources of genetic quality and mate choice models for self-referential disassortative mating based on optimal levels of genetic dissimilarity. We reviewed the empirical evidence for genetic-complementarity-based female mate choice among birds. We found the evidence for such choice is mixed but in general against the genetic complementarity hypothesis. The lack of evidence for genetic complementarity in many birds may be due to an inability to make the fine distinctions among potential mates based on genes, possibly due to the comparative anosmatic nature of avian sensory system. For some species however there is compelling evidence for genetic complementarity as a criterion used in female mate choice. Understanding the ubiquity of female mate choice based on genetic complementarity and the variation in this source of female preference among and within species remains a challenge.