Optogenetic Activation of the fruitless -Labeled Circuitry in Drosophila subobscura Males Induces Mating Motor Acts

It remains an enigma how the nervous system of different animal species produces different behaviors. We studied the neural circuitry for mating behavior in , a species that displays unique courtship actions not shared by other members of the genera including the genetic model , in which the core courtship circuitry has been identified. We disrupted the ( ) gene, a master regulator for the courtship circuitry formation in , resulting in complete loss of mating behavior. We also generated , which expresses the optogenetic activator Chrimson fused with a fluorescent marker under the native promoter. The -labeled circuitry in visualized by revealed differences between females and males, optogenetic activation of which in males induced mating behavior including attempted copulation. These findings provide a substrate for neurogenetic dissection and manipulation of behavior in non-model animals, and will help to elucidate the neural basis for behavioral diversification. How did behavioral specificity arise during evolution? Here we attempted to address this question by comparing the parallel genetically definable neural circuits controlling the courtship behavior of , a genetic model, and its relative, , which exhibits a courtship behavioral pattern unique to it, including nuptial gift transfer. We found that the circuit, which is required for male courtship behavior, was slightly but clearly different from its counterpart, and that optogenetic activation of this circuit induced -specific behavior, i.e., regurgitating crop contents, a key element of transfer of nuptial gift. Our study will pave the way for determining how and which distinctive cellular elements within the circuit determine the species-specific differences in courtship behavior.