Data from: A Drosophila female pheromone elicits species-specific long-range attraction via an olfactory channel with dual specificity for sex and food

Background: Mate finding and recognition in animals evolves during niche adaptation and involves social signals and habitat cues. Drosophila melanogaster and related species are known to be attracted to fermenting fruit for feeding and egg-laying, which poses the question of whether species-specific fly odours contribute to long-range premating communication.

Results: We have discovered an olfactory channel in D. melanogaster with a dual affinity to sex and food odorants. Female flies release a pheromone, (Z)-4-undecenal (Z4-11Al), that elicits flight attraction in both sexes. Its biosynthetic precursor is the cuticular hydrocarbon (Z,Z)-7,11-heptacosadiene (7,11-HD), which is known to afford reproductive isolation between the sibling species D. melanogaster and D. simulans during courtship. Twin olfactory receptors, Or69aB and Or69aA, are tuned to Z4-11Al and food odorants, respectively. They are co-expressed in the same olfactory sensory neurons, and feed into a neural circuit mediating species-specific, long-range communication; however, the close relative D. simulans, which shares food resources with D. melanogaster, does not respond to Z4-11Al.

Conclusion: The Or69aA and Or69aB isoforms have adopted dual olfactory traits. The underlying gene yields a collaboration between natural and sexual selection, which has the potential to drive speciation.

研究背景：动物的配偶搜寻与识别行为会随生态位适应而演化，该过程涉及社会信号与栖息地线索。已知黑腹果蝇（Drosophila melanogaster）及其近缘物种会被发酵水果吸引以取食和产卵，这引发了一个问题：物种特异性的果蝇气味是否参与了远距离的交配前通讯？
研究结果：我们在黑腹果蝇（Drosophila melanogaster）中发现了一条对性信息素与食物气味兼具亲和性的嗅觉通路。雌性果蝇会释放一种信息素——(Z)-4-十一碳烯醛（(Z)-4-undecenal，简称Z4-11Al），该物质可诱导雌雄果蝇的飞行趋化行为。该信息素的生物合成前体为表皮碳氢化合物(Z,Z)-7,11-二十七碳二烯（(Z,Z)-7,11-heptacosadiene，简称7,11-HD），已知该物质可在求偶过程中介导黑腹果蝇（D. melanogaster）与拟暗果蝇（Drosophila simulans）这对姊妹种之间的生殖隔离。嗅觉受体Or69aB与Or69aA分别对Z4-11Al与食物气味产生响应。二者在同一嗅觉感觉神经元中共表达，并共同参与介导物种特异性远距离通讯的神经环路；但与黑腹果蝇共享食物资源的近缘物种拟暗果蝇（Drosophila simulans）并不会对Z4-11Al产生响应。
研究结论：Or69aA与Or69aB两种受体亚型具备双重嗅觉功能特性。其编码基因可同时受自然选择与性选择共同调控，这一机制有望推动物种形成过程。