Fertility Advertisement by Female Sailfin Mollies, Poecilia latipinna (Pisces: Poeciliidae)

Abstract

levels of competition for mates. We examined whether males of the live-bearing sailfin mollie, Poecilia latipinna, were able to recognize when females were carrying fertilizable ova. Males dramatically increased their rates of sexual behavior toward females immediately after they gave birth. Males also displayed higher rates of sexual behavior toward virgin females than toward gravid females. Fertility advertisement by females allows intermale competition to be focused on a few individual females at any one time. This focus appears to provide a reproductive advantage to larger male mollies and is thus an important element influencing the outcome of sexual selection. We suggest that fertility advertisement by females may play a similarly important role in other poeciliids.