Scent, Mate Choice and Genetic Heterozygosity

Females of many species choose to mate with relatively unrelated males in order to ensure outbred, heterozygous offspring. There is some evidence to suggest that the MHC is involved in mate choice decisions, either because MHC heterozygous offspring are more resistant to disease, or because the highly detectable odours associated with this region allow it to act as a marker of general inbreeding. To determine which role the MHC plays it is necessary to disentangle this region from the genetic background, a requirement which has generally proven difficult to achieve. We argue that the emphasis on MHC’s role in mate choice has resulted in other potential markers of inbreeding being neglected, and discuss the evidence for MHC disassortative mating, the interaction with genetic background, and a possible role for alternative markers of inbreeding.