Genetic and neural mechanisms that inhibit Drosophila from mating with other species.

Genetically hard-wired neural mechanisms must enforce behavioral reproductive isolation because interspecies courtship is rare even in sexually naïve animals of most species. We find that the chemoreceptor Gr32a inhibits male D. melanogaster from courting diverse fruit fly species. Gr32a recognizes nonvolatile aversive cues present on these reproductively dead-end targets, and activity of Gr32a neurons is necessary and sufficient to inhibit interspecies courtship. Male-specific Fruitless (Fru(M)), a master regulator of courtship, also inhibits interspecies courtship. Gr32a and Fru(M) are not coexpressed, but Fru(M) neurons contact Gr32a neurons, suggesting that these genes influence a shared neural circuit that inhibits interspecies courtship. Gr32a and Fru(M) also suppress within-species intermale courtship, but we show that distinct mechanisms preclude sexual displays toward conspecific males and other species. Although this chemosensory pathway does not inhibit interspecies mating in D. melanogaster females, similar mechanisms appear to inhibit this behavior in many other male drosophilids.

Fan P ，Manoli DS ，Ahmed OM ，Chen Y ，Agarwal N ，Kwong S ，Cai AG ，Neitz J ，Renslo A ，Baker BS ，Shah NM ... -  《-》

Evolution of Mechanisms that Control Mating in Drosophila Males.

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.

Ahmed OM ，Avila-Herrera A ，Tun KM ，Serpa PH ，Peng J ，Parthasarathy S ，Knapp JM ，Stern DL ，Davis GW ，Pollard KS ，Shah NM ... -  《Cell Reports》

fruitless tunes functional flexibility of courtship circuitry during development.

Drosophila male courtship is controlled by the male-specific products of the fruitless (fruM) gene and its expressing neuronal circuitry. fruM is considered a master gene that controls all aspects of male courtship. By temporally and spatially manipulating fruM expression, we found that fruM is required during a critical developmental period for innate courtship toward females, while its function during adulthood is involved in inhibiting male-male courtship. By altering or eliminating fruM expression, we generated males that are innately heterosexual, homosexual, bisexual, or without innate courtship but could acquire such behavior in an experience-dependent manner. These findings show that fruM is not absolutely necessary for courtship but is critical during development to build a sex circuitry with reduced flexibility and enhanced efficiency, and provide a new view about how fruM tunes functional flexibility of a sex circuitry instead of switching on its function as conventionally viewed.

Chen J ，Jin S ，Chen D ，Cao J ，Ji X ，Peng Q ，Pan Y ... -  《eLife》

Neurogenetics of courtship and mating in Drosophila.

Villella A ，Hall JC 《Advances in Genetics》

Methyl-CpG binding domain proteins inhibit interspecies courtship and promote aggression in Drosophila.

Gupta T ，Morgan HR ，Andrews JC ，Brewer ER ，Certel SJ ... -  《-》