Data from: Patterns of physiological decline due to age and selection in Drosophila melanogaster

In outbred sexually reproducing populations, age-specific mortality rates reach a plateau in late life following the exponential increase in mortality rates that marks aging. Little is known about what happens to physiology when cohorts transition from aging to late life. We measured age-specific values for starvation resistance, desiccation resistance, time-in-motion and geotaxis in ten Drosophila melanogaster populations: five populations selected for rapid development and five control populations. Adulthood was divided into two stages, the aging phase and the late-life phase according to demographic data. Consistent with previous studies, we found that populations selected for rapid development entered the late-life phase at an earlier age than the controls. Age-specific rates of change for all physiological phenotypes showed differences between the aging phase and the late-life phase. This result suggests that late life is physiologically distinct from aging. The ages of transitions in physiological characteristics from aging to late life statistically match the age at which the demographic transition from aging to late life occurs, in all cases but one. These experimental results support evolutionary theories of late life that depend on patterns of decline and stabilization in the forces of natural selection.

在远交有性繁殖种群中，年龄特异性死亡率在标志着衰老的死亡率指数增长之后，会在晚年后期进入平台期。目前对于种群队列从衰老阶段过渡到晚年后期时其生理机能发生的变化，尚缺乏深入了解。我们对10个黑腹果蝇（Drosophila melanogaster）种群的年龄特异性指标进行了测定，涵盖抗饥饿能力、抗干燥能力、运动时长与趋地性；其中5个种群为快速发育选育种群，剩余5个为对照种群。根据种群统计数据，我们将成虫期划分为衰老阶段与晚年后期两个阶段。与既往研究结果一致，我们发现快速发育选育种群比对照种群更早进入晚年后期阶段。所有生理表型的年龄特异性变化速率，在衰老阶段与晚年后期阶段之间均存在显著差异。该结果表明，晚年后期在生理机能层面与衰老阶段存在本质区别。除1个例外情况外，所有种群队列的生理特征从衰老阶段过渡到晚年后期的年龄，在统计学上均与种群统计层面的衰老-晚年后期过渡年龄相吻合。本实验结果支持晚年后期进化理论，这类理论的核心依据是自然选择压力的衰减与稳定模式。