Heritability of body mass, a sexually selected trait, in an arctiid moth (Utetheisa ornatrix).

In the moth Utetheisa ornatrix (Lepidoptera: Arctiidae), females mate preferentially with larger males. Large body mass is advantageous to both sexes: large males sire more young than small males, and large females have higher fecundity than small females. Here we report that body mass is heritable in both sexes, indicating that by choosing larger males females obtain genetic benefits for their offspring. Choosy females also receive extra nutrient and defensive alkaloid by way of their partner's spermatophores, but these gifts do not affect the heritability of body mass. These results indicate that by exercising mate choice female Utetheisa receive both direct phenotypic and indirect genetic benefits.