Effect of predation on male mating behaviour in a unisexual-bisexual mating system

Abstract

AbstractMate choice for conspecifics is beneficial when closely related species live in sympatry, but mate choice can be costly in the presence of predators. Male sailfin mollies are sexually parasitized by gynogenetic Amazon mollies. Amazon mollies must mate with male sailfin mollies to initiate embryogenesis, but inheritance is maternal. We tested if male sailfin molly mate choice for conspecific females is affected by predation risk. Male mate choice was tested in one of four treatments: (1) predation/no refuge, (2) predation/refuge, (3) no predation/refuge and (4) no predation/no refuge. Predation consisted of dipping the beak of a great blue heron decoy in the aquarium prior to a mating trial. Refuge was provided by java-moss. For each trial the number of mating attempts toward each female was recorded. There was a significant interaction between predation and refuge on strength of preference (SOP) for conspecific females. The highest SOP was in the no predator/no refuge treatment, and the lowest SOP was in the predator/no refuge treatment. These results suggest that the cost of predation is higher than the cost of mating with heterospecifics, and that the presence of a refuge may reduce this cost. This could explain the continued maintenance of Amazon mollies.