Data from: Patterns of male fitness conform to predictions of evolutionary models of late-life

We studied lifetime male virility, a male fitness component, in five populations of Drosophila melanogaster. Virility was measured as the number of females, out of eight total, that a male could fertilize in 24 hours. Individual males were measured at weekly intervals until they died. Virility declined in an approximately linear fashion for the first three weeks of adult life. It then stayed low but relatively constant for another three weeks, exhibiting a clear plateau. These observations are consistent with the evolutionary theories of late-life.The results were not consistent with a simple heterogeneity theory of late-life. This is the first demonstration of a late-life plateau for a male fitness component. We also found that the virility of males that were within seven days of death was significantly lower than similarly aged males that were not about to die. This rapid deterioration of virility prior to death, or death spiral, is similar to a decline in fecundity that we had previously documented.

我们针对5个黑腹果蝇（Drosophila melanogaster）种群，研究了作为雄性适合度组分的终生雄性生育力。雄性生育力的测定方式为：单只雄性在24小时内可使8只供试雌蝇中成功受精的雌蝇数量。我们对每只雄性个体每周开展一次测定，直至其死亡。在成虫期的前3周，雄性生育力大致呈线性下降趋势；随后的3周内，其生育力维持在较低水平且相对稳定，呈现出明显的平台期。上述观测结果与衰老后期的进化理论相符，但并不符合衰老后期的单一异质性理论。本研究首次证实了雄性适合度组分存在衰老后期平台期这一现象。我们还发现，距死亡不足7天的雄性个体，其生育力显著低于同龄且暂无死亡风险的雄性。这种死亡前生育力的快速衰退（即死亡螺旋），与我们此前记录的繁殖力下降现象高度相似。