The contribution of female mate choice and pupal mating to the reproductive isolation between the butterflies <em>Heliconius erato</em> and <em>Heliconius himera</em>

Abstract

Alternative mating tactics, mutual mate choice, and multiple mating cues can contribute to reproductive isolation but are rarely all addressed in case studies of speciation. Here, we dissected the behavioral components of assortative mating using the closely related parapatric butterflies <em>Heliconius erato cyrbia</em> and <em>Heliconius himera</em>. We tested male and female preference, the role of geography, the use of color or pheromones in female choice, and male choice in pupal mating, and an alternative mating tactic. We found evidence of female preference for conspecific males in both species, while only <em>H. erato</em> males showed evidence of courtship preference. Female <em>H. himera</em> rejected males with blocked androconial pheromones over controls but did not show bias against males with altered coloration. In the context of pupal mating, an alternative mating strategy, we observed only <em>H. erato</em> males were less likely to make interspecies mating mistakes. This work underscores the importance of collecting behavioral data to the study of speciation and highlights how multiple traits can contribute to reproductive isolation even between closely related species.