FEMALE PREFERENCE FOR SYMMETRICAL VERTICAL BARS IN MALE SAILFIN MOLLIES

Fluctuating asymmetry is defined as random deviation from perfect bila teral symmetry in otherwise symmetrical morphological traits and origi nates from developmental errors during ontogeny. It is thought to refl ect the inability of a genotype to buffer itself effectively against e nvironmental perturbations, thus providing an honest phenotypic indica tor of genetic quality. It has been proposed that females use the degr ee of asymmetry in male ornaments to assess male quality in mate choic e. We studied whether fluctuating asymmetry in vertical bars in the sa ilfin molly, Poecilia latipinna, is a criterion in female mate prefere nce, as has been shown before in a swordtail, Xiphophorus cortezi. Usi ng both live stimulus males and silicon models, we found that females have significant preferences both for bars per se and for males with s ymmetrical bars. The total number of bars and the degree of fluctuatin g asymmetry were negatively related so fluctuating asymmetry in bars m ay be an honest signal. This phenomenon may have influenced the evolut ion of the male courtship display in P. latipinna. (C) 1998 The Associ ation for the Study of Animal Behaviour.