Familiarity leads to female mate preference for novel males in the guppy, Poecilia reticulata

Guppies are a model vertebrate for studies of sexual selection and life his tory evolution. None the less, there have been few investigations of the fa ctors responsible for maintaining extreme within-population genetic variati on in male coloration. In a laboratory study, we tested the hypothesis that frequency-dependent mate choice contributes to the maintenance of this var iation. We attempted to avoid biases inherent in earlier studies of the 'ra re male effect' by familiarizing females to males bearing a particular colo ur pattern and later presenting them with alternate male types, in equal nu mbers. Females were significantly more likely to mate with males having nov el colour patterns than with males having a colour pattern with which they were familiar. This result is consistent with the hypothesis that mate choi ce is frequency dependent. Other factors such as male and female size were unrelated to mate preference. Implications of the results for theories of s exual selection and the maintenance of variation are discussed. (C)1999 The Association for the Study of Animal Behaviour.