Evolutionary ecology of senescence in the wild

不久前，动物的衰老被认为是实验室的产物，因为人们普遍认为很少有野生动物能活到衰老的程度。我们现在知道，衰老不仅在野外可以检测到，而且在非常长寿的动物中，高达90%的死亡与衰老有关。然而，我们仍然对野生动物衰老的潜在过程知之甚少，这些过程如何导致生活史和健康状况的变化，以及实验室发生的衰老过程如何转化为野外衰老过程。我和我的学生利用两个都涉及飞行有机体的模型系统--在捕食和饥饿下进化的果蝇(一个项目)和两个长期野外观测站的长寿海鸟(三个项目)--来解开其中的一些谜团。首先，我们建议通过探索肌肉损伤导致觅食能力降低是否是野生动物衰老的主要原因来研究潜在的过程。其次，我们建议通过测试生活史轨迹在很大程度上取决于生物年龄(生理条件)而不是时间年龄的想法来测试老龄化的生态后果。第三，我们建议考察个体在衰老轨迹上的可塑性是否与健康有关。最后，我们建议通过实验选择自然死亡率较高的果蝇来测试进化理论，以确定外部死亡率的变化如何影响内在死亡率。我们感兴趣的是，在实验室适应的果蝇的衰老如何转化为“野生”(饥饿和狩猎)果蝇的衰老。我的研究计划将提供对野外衰老的进化生态学的洞察。对这类基础研究的比较方法可能会影响我们延长动物健康寿命和为野生动物保护提供年龄结构模型的能力。

Not long ago, senescence in animals was dismissed as an artifact of the lab as it was widely believed that few wild animals lived long enough to senesce. We now know that senescence is not only detectable in the wild, but up to 90% of mortality in very long-lived animals is associated with senescence. Yet we still have a poor understanding of the processes underlying senescence in the wild, how those processes cause variation in life-history and fitness, and how ageing processes occurring in the lab translate to the wild. Using two model systems both involving flying organisms, Drosophila that have evolved under predation and starvation (one project) and long-lived seabirds at two long-term field stations (three projects), my students and I propose to unravel some of these mysteries. First, we propose to investigate the underlying processes by exploring whether muscle damage leading to reduced foraging abilities is a major cause of senescence in the wild. Second, we propose to test the ecological ramifications of ageing by testing the idea that life-history trajectories depend largely on biological age (physiological condition) rather than chronological age. Third, we propose to examine whether individual plasticity in ageing trajectories is associated with fitness. Lastly, we propose to test evolutionary theory by experimentally selecting for Drosophila with high levels of naturally occurring mortality to determine how variation in extrinsic mortality can influence intrinsic mortality rates. We are interested in how ageing in lab-adapted Drosophila translates to ageing in “wild” (starved and hunted) Drosophila. My research program will provide insight into the evolutionary ecology of senescence in the wild. A comparative approach to such basic research may impact our ability to prolong the healthy lifespan of animals and to provide age-structured models for wildlife conservation.