Dynamics of learning in the context of courtship in Drosophila persimilis and D. pseudoobscura

Recent data indicating that male fruit flies adaptively reduce courtship of heterospecific females, which typically reject them, suggest that learning could contribute to reduced levels of matings between individuals from diverging populations with partial premating isolation. To further examine the robustness of learning in the context of courtship in fruit flies, I wished to broaden the types of experience provided to males prior to testing. In both Drosophila persimilis and D. pseudoobscura, alternating trials of mating with conspecific females and rejection by heterospecific females produced the strongest reduction in heterospecific courtship. Trials of rejection by heterospecific females produced equally strong reduction in heterospecific courtship in D. persimilis but not in D. pseudoobscura, whereas trials of mating with conspecific females did not reduce heterospecific courtship at all. The pattern of strong reduction in heterospecific courtship was also replicated when I simulated the likely natural scenario in which males interact with conspecific females since eclosion and later encounter and experience rejection by heterospecific females. The results indicate that a variety of relevant experiences cause a rapid decrease in the time that male fruit flies spend courting heterospecific females. Such learning in partially reproductively isolated populations could contribute to speciation.