Laboratory of Neurophysiology and Behavior, The Rockefeller University, New York, NY, USA.
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
Nature. 2018 Jul;559(7715):564-569. doi: 10.1038/s41586-018-0322-9. Epub 2018 Jul 11.
Courtship rituals serve to reinforce reproductive barriers between closely related species. Drosophila melanogaster and Drosophila simulans exhibit reproductive isolation, owing in part to the fact that D. melanogaster females produce 7,11-heptacosadiene, a pheromone that promotes courtship in D. melanogaster males but suppresses courtship in D. simulans males. Here we compare pheromone-processing pathways in D. melanogaster and D. simulans males to define how these sister species endow 7,11-heptacosadiene with the opposite behavioural valence to underlie species discrimination. We show that males of both species detect 7,11-heptacosadiene using homologous peripheral sensory neurons, but this signal is differentially propagated to P1 neurons, which control courtship behaviour. A change in the balance of excitation and inhibition onto courtship-promoting neurons transforms an excitatory pheromonal cue in D. melanogaster into an inhibitory cue in D. simulans. Our results reveal how species-specific pheromone responses can emerge from conservation of peripheral detection mechanisms and diversification of central circuitry, and demonstrate how flexible nodes in neural circuits can contribute to behavioural evolution.
求偶仪式有助于加强亲缘关系密切的物种之间的生殖隔离。黑腹果蝇和拟暗果蝇表现出生殖隔离，部分原因是黑腹果蝇雌性产生 7,11-二十七碳二烯，一种信息素，促进黑腹果蝇雄性的求偶，但抑制拟暗果蝇雄性的求偶。在这里，我们比较了黑腹果蝇和拟暗果蝇雄性中的信息素处理途径，以确定这两个姐妹物种如何赋予 7,11-二十七碳二烯相反的行为效价，从而实现物种识别。我们表明，两种物种的雄性都使用同源的外周感觉神经元来检测 7,11-二十七碳二烯，但这种信号被差异地传递到控制求偶行为的 P1 神经元。对促进求偶神经元的兴奋和抑制的平衡的改变将黑腹果蝇中的兴奋性信息素线索转化为拟暗果蝇中的抑制性线索。我们的研究结果揭示了特定物种的信息素反应如何从外周检测机制的保守和中枢电路的多样化中产生，并证明了神经回路中的灵活节点如何有助于行为进化。
