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 capti...经典衰老理论将外源性死亡率（extrinsic mortality, EM）视为塑造寿命与衰老进程的核心因素，但当前多数关于功能性衰老的研究均聚焦于外源性死亡率较低的物种。这种研究偏向或导致跨类群种群统计过程中，对性能衰老衰退相较于条件依赖性死亡率的影响程度产生高估。为同时探究功能性衰老（functional senescence, FS）以及内源性、外源性与条件依赖性死亡率在自然中捕食风险较高物种中的作用，本研究依托纵向监测数据（对853只成年个体进行全程跟踪），对比了野生与圈养灰鼠狐猴（Microcebus murinus）的体质量（body mass, BM）年龄变化轨迹。本研究在两种生存环境中均发现了非随机死亡率的相关证据。在圈养环境中，最年长的个体展现出体质量恢复能力的衰老现象，而野生个体则未观测到功能性衰老的相关证据。总体而言，圈养个体的寿命更长，但野生与圈养群体间观测到寿命的性别偏向性出现逆转