Disentangling the relationship between age and reproduction is central to understand life-history evolution, and recent evidence shows that considering condition-dependent mortality is a crucial piece of this puzzle. For example, non-random mortality of "low-condition" individuals can lead to an increase in average lifespan. However, selective disappearance of such low-condition individuals may also affect reproductive senescence at the population level due to trade-offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition-dependent extrinsic mortality (i.e. simulated predation) may increase the age-related decline in male reproductive success, and with it the potential for sexual conflict, by comparing reproductive ageing in Drosophila melanogaster male/female cohorts exposed (or not) to condition-dependent simulated predation across time. While female reproductive senescence was not affected by predation, male reproductive senescence was considerably higher under predation, due mainly to an accelerated decline in offspring viability of "surviving" males with age. This sex-specific effect suggests that condition-dependent extrinsic mortality can exacerbate survival-reproductive trade-offs in males, which are typically under stronger condition-dependent selection than females. Interestingly, condition-dependent extrinsic mortality did not affect mating success, hinting that accelerated reproductive senescence is due to a decrease in male post-copulatory fitness components. Our results support the recent proposal that male ageing can be an important source of sexual conflict, further suggesting this effect could be exacerbated under more natural conditions.

中文翻译：

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病情依赖性死亡率加剧男性（但不是女性）生殖衰老和性冲突的可能性


理清年龄和繁殖之间的关系是理解生活史进化的核心，最近的证据表明，考虑条件依赖性死亡率是解决这个难题的关键部分。例如，“低素质”个体的非随机死亡可以导致平均寿命的延长。然而，由于与生存/寿命相关的生理功能和生殖功能的维持之间的权衡，这种低条件个体的选择性消失也可能影响种群水平的生殖衰老。在这里，我们通过比较暴露的果蝇雄性/雌性群体的生殖衰老，提出了这样一种观点，即条件依赖性外在死亡率（即模拟捕食）可能会增加雄性生殖成功率与年龄相关的下降，并可能导致性冲突。 （或不）随时间变化的条件依赖性模拟捕食。虽然雌性生殖衰老不受捕食影响，但雄性生殖衰老在捕食下要高得多，这主要是由于“幸存”雄性的后代活力随着年龄的增长而加速下降。这种性别特异性效应表明，条件依赖性外在死亡率会加剧男性的生存与繁殖权衡，而男性通常比女性受到更强的条件依赖性选择。有趣的是，条件依赖性外在死亡率并不影响交配成功，这表明生殖衰老加速是由于雄性交配后健康成分的减少所致。我们的研究结果支持了最近提出的观点，即男性衰老可能是性冲突的一个重要根源，进一步表明这种影响在更自然的条件下可能会加剧。