Characterizing the mating behaviours of the Tamesí molly, Poecilia latipunctata, a sailfin with shortfin morphology

The Tamesí molly is an unusual molly species because it has features of both shortfin and sailfin mollies. Morphologically, it is classified as a shortfin species, yet phylogenetic evidence and observations of male courtship behaviour indicate that it should be classified as a sailfin molly. We characterized the mating behavioural profiles of dark and silver male P. latipunctata by varying the competitive environment (presence or absence of male competitors) and the degree of female receptivity (unreceptive versus receptive females), both factors known to increase rates of courtship displays in sailfin species. We measured rates of three mating behaviours: courtship displays, gonoporal nibbles and gonopodial thrusts (forced insemination attempts) under both types of competitive and female receptivity conditions. Rates of courtship displays were strongly influenced by female receptive state; both dark and silver males elevated their rates of courtship displays in the presence of receptive females in either competitive environment. In addition, the influence of competition for mates (presence of a competitor) had a stronger effect on the courtship display rates of dark males, but only in the presence of receptive females; courtship display rates were almost eight times higher for dark males when at least one female in the social group was receptive (≤24 h postpartum). These results suggest that dark males actively compete for receptive females by increasing their reliance on courtship, a behavioural response clearly characteristic of other sailfin molly species.