Data from: Senescence or selective disappearance? Age trajectories of body mass in wild and captive populations of a small-bodied primate

Classic theories of ageing consider extrinsic mortality (EM) a major factor in shaping longevity and ageing, yet most studies of functional ageing focus on species with low EM. This bias may cause overestimation of the influence of senescent declines in performance over condition-dependent mortality on demographic processes across taxa. To simultaneously investigate the roles of functional senescence (FS) and intrinsic, extrinsic and condition-dependent mortality in a species with a high predation risk in nature, we compared age trajectories of body mass (BM) in wild and captive grey mouse lemurs (Microcebus murinus) using longitudinal data (853 individuals followed through adulthood). We found evidence of non-random mortality in both settings. In captivity, the oldest animals showed senescence in their ability to regain lost BM, whereas no evidence of FS was found in the wild. Overall, captive animals lived longer, but a reversed sex bias in lifespan was observed between wild and captive populations. We suggest that even moderately condition-dependent EM may lead to negligible FS in the wild. While high EM may act to reduce the average lifespan, this evolutionary process may be counteracted by the increased fitness of the long-lived, high-quality individuals.经典衰老理论将外源性死亡率（extrinsic mortality, EM）视作塑造寿命与衰老进程的关键因素，但现有功能衰老相关研究大多聚焦于外源性死亡率较低的物种。这种偏倚可能会导致高估性能衰老衰退相较于条件依赖型死亡率，对各物种种群统计过程的影响。为同时探究功能衰老（functional senescence, FS）、内源性、外源性以及条件依赖型死亡率在自然中高捕食风险物种中的作用，我们依托纵向研究数据（共追踪853只成年个体），比较了野生与圈养灰鼠狐猴（Microcebus murinus）的体重（body mass, BM）年龄变化轨迹。我们在两种环境中均观测到非随机死亡的证据。圈养环境中，最年长的个体展现出体重恢复能力的衰老衰退，而野生种群中未观测到功能衰老的迹象。总体而言，圈养个体的寿命更长，但野生与圈养种群间呈现出相反的寿命性别偏倚。我们推测，即便仅为中等程度的条件依赖型外源性死亡率，也可能使野生种群的功能衰老程度可忽略不计。尽管高外源性死亡率会缩短种群平均寿命，但这一进化过程可被长寿且高质量个体的更高适合度所抵消。