Data from: Sex-specific effects of natural and sexual selection on the evolution of life span and ageing in Drosophila simulans

1. Variation in the strength of age-dependent natural selection shapes differences in ageing rates across species and populations. Likewise, sexual selection can promote divergent patterns of senescence across the sexes. However, the effects of these processes on the evolution of ageing have largely been considered independently, and interactions between them are poorly understood.

2. We use experimental evolution to investigate how natural and sexual selection affect life span and ageing in Drosophila simulans.

3. Replicate populations were evolved under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and at one of two temperatures, 25 °C (relaxed natural selection) or 27 °C (enhanced natural selection), in a fully factorial design. We measured longevity in 150 individually housed flies taken from each of three replicate populations per selection regime.

4. We found that natural and sexual selection affected the evolution of life span via sex-specific effects on different ageing parameters (ageing rate vs. baseline mortality): natural selection reduced the rate of ageing in both sexes but increased male baseline mortality, while sexual selection elevated baseline mortality in both sexes but particularly in males.

5. This means that sexual and natural selection interacted to reduce male life span but acted on female life span by independently affecting particular ageing parameters. Sex-specific effects of sexual and natural selection may help explain the diverse patterns of ageing seen in nature but complicate predictions about how ageing and life span evolve across the sexes

1. 年龄依赖性自然选择的强度变异，塑造了不同物种及种群间的衰老速率差异。同样，性选择可推动两性间衰老模式的分化。然而，此前学界大多独立探讨这两类过程对衰老演化的影响，二者间的交互作用机制仍有待阐明。
2. 本研究通过实验演化手段，探究自然选择与性选择如何影响拟果蝇（Drosophila simulans）的寿命与衰老进程。
3. 本实验采用完全析因设计，将重复种群分别置于两种性选择条件（终生单配偶制，即弱化性选择；终生多配偶制，即强化性选择）与两种温度条件（25℃，即弱化自然选择；27℃，即强化自然选择）下进行演化培养。我们从每个选择处理组的3个重复种群中各选取150只单只饲养的果蝇，测定其寿命。
4. 研究结果显示，自然选择与性选择通过对不同衰老参数（衰老速率与基线死亡率）产生性别特异性效应，进而影响寿命的演化：自然选择可降低两性的衰老速率，但会提升雄性的基线死亡率；而性选择则会升高两性的基线死亡率，尤以雄性为甚。
5. 这表明，性选择与自然选择的交互作用会缩短雄性寿命，而二者则通过独立作用于特定衰老参数来影响雌性寿命。自然选择与性选择的性别特异性效应，或可解释自然界中观测到的多样衰老模式，但也使得预测两性间衰老与寿命的演化轨迹变得更为复杂。