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Summary: Genetically wired neural mechanisms inhibit mating between species because even naive animals rarely mate with other species. These mechanisms can evolve through changes in expression or function of key genes in sensory pathways or central circuits. Gr32a is a gustatory chemoreceptor that, in D. melanogaster, is essential to inhibit interspecies courtship and sense quinine. Similar to D. melanogaster, we find that D. simulans Gr32a is expressed in foreleg tarsi, sensorimotor appendages that inhibit interspecies courtship, and it is required to sense quinine. Nevertheless, Gr32a is not required to inhibit interspecies mating by D. simulans males. However, and similar to its function in D. melanogaster, Ppk25, a member of the Pickpocket family, promotes conspecific courtship in D. simulans. Together, we have identified distinct evolutionary mechanisms underlying chemosensory control of taste and courtship in closely related Drosophila species. : Mechanisms that inhibit interspecies mating are critical to reproductive isolation of species. Ahmed et al. show that Gr32a, a chemoreceptor that inhibits interspecies courtship by D. melanogaster males, does not inhibit this behavior in the closely related D. simulans, indicating rapid evolution of peripheral sensory mechanisms that preclude interspecies breeding. Keywords: Gr32a, Gr33a, Ppk25, chemosensation, pheromones, evolution, reproduction, reproductive isolation, courtship, mating |
