Humans and other animals wittingly or unwittingly run risk–benefit analyses daily. For animals of reproductive age, a prime example of such analysis is assessing the benefit of reproductive success versus the cost of being preyed upon. The scale needs to be sensitive: over-prioritize survival at the risk of a lack of progeny, or undermine danger at the risk of perishing. While previous studies and empirical knowledge have suggested that males become less preoccupied about potential danger upon permissive cues indicating increased probability of successful copulation, the molecular mechanisms orchestrating this behavior have remained ill-understood.

Writing in Nature, Cazalé-Debat et al. remedy this gap in understanding and provide notable mechanistic and functional insight into the neurons, receptors and signaling cascades that regulate the trade-off between survival and propagation in Drosophila. Using sex–danger conflict assays, the authors demonstrate that though male flies abort courtship upon danger cues at early stages, they increasingly disregard visual threats as courtship progresses and copulation becomes more likely. The initial abortive response seems to be regulated by visual activation of LC16 neurons, which then turn on 5-HT^PMPD neurons (serotonin neurons in the posterior medial dorsal cluster) and activate the release of serotonin; the latter inhibits P1 and plP10 neurons, thus turning off key hubs that are known to be activated during courtship. This allows flies to prioritize survival over reproduction.

人类和其他动物每天都在有意或无意地进行风险-收益分析。对于育龄动物，这种分析的一个主要例子是评估繁殖成功的好处与被捕食的成本。天平需要敏感：冒着缺乏后代的风险过分优先考虑生存，或者冒着灭亡的风险破坏危险。虽然以前的研究和实证知识表明，雄性在表明成功交配的可能性增加的允许性暗示时，对潜在危险的关注度会降低，但协调这种行为的分子机制仍然不清楚。

Cazalé-Debat 等人在《自然》杂志上撰文，弥补了这一理解空白，并提供了对神经元、受体和信号级联反应的显着机制和功能见解，这些级联调节果蝇生存和繁殖之间的权衡。使用性-危险冲突分析，作者证明，尽管雄性果蝇在早期阶段会因危险线索而中止求偶，但随着求偶的进行和交配的可能性增加，它们越来越无视视觉威胁。最初的流产反应似乎受到 LC16 神经元视觉激活的调节，然后打开 5-HT^PMPD 神经元（后内侧背簇中的血清素神经元）并激活血清素的释放;后者抑制 P1 和 plP10 神经元，从而关闭已知在求偶过程中激活的关键枢纽。这使得苍蝇能够将生存置于繁殖之上。