Cohort effects, reflecting early adversity or advantage, have persisting consequences for growth, reproductive onset, longevity, and lifetime reproductive success. In species with prolonged life histories, cohort effects may establish variation in age-sex structures, while social structure may buffer individuals against early adversity. Using periods of significant ecological adversity, we examined cohort effects for male and female elephants (Loxodonta africana) over almost 50 years in Amboseli, Kenya. Mortality spiked during severe droughts with highest mortality among calves under 2 years and females over 40 years. Deaths of oldest females resulted in social disruption via matriarch turnover, with potential impacts on resource acquisition for survivors. We predicted that survivors of high mortality and social challenges would have altered life-history trajectories, with later age at first reproduction and reduced age-specific fertility for females and slow transitions to independence and late-onset of potential mating or musth among males. Contrary to expectations, there were no persisting early drought effects on female age at first conception while matriarch loss around puberty accelerated reproductive onset. Experience of an early life drought did not influence age-specific reproductive rates once females commenced reproduction. Males who survived an early drought exhibited complex consequences: male age at family independence was later with larger peer cohort size, but earlier with drought in year of independence (13.9 vs 14.6 years). Early drought had no effect on age at first musth, but male reproductive onset was weakly associated with the number of peers (negative) and age at independence (positive).

中文翻译：

---

干旱和家庭破裂对雄性和雌性非洲象的影响

反映早期逆境或优势的队列效应对生长、繁殖开始、寿命和终生繁殖成功具有持续的影响。在具有较长生命史的物种中，队列效应可能会导致年龄-性别结构的差异，而社会结构可能会缓冲个体免受早期逆境的影响。利用重大生态逆境时期，我们研究了肯尼亚安博塞利近 50 年来雄性和雌性大象（非洲非洲象属）的队列效应。严重干旱期间死亡率飙升，其中 2 岁以下的小牛和 40 岁以上的母牛死亡率最高。最年长女性的死亡通过女族长更替导致社会混乱，对幸存者的资源获取有潜在影响。我们预测，高死亡率和社会挑战的幸存者将改变生活史轨迹，女性首次繁殖年龄较晚，特定年龄生育能力降低，男性向独立过渡缓慢，潜在交配或发情晚。与预期相反，早期干旱对初次受孕的女性年龄没有持续的影响，而青春期前后的母系丧失加速了生殖开始。一旦雌性开始繁殖，早期生活干旱的经历并不会影响特定年龄的繁殖率。在早期干旱中幸存下来的男性表现出复杂的后果：男性家庭独立年龄较晚，同龄群体规模较大，但独立年份干旱较早（13.9 岁对 14.6 岁）。早期干旱对初发时的年龄没有影响，