Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.
J Anim Ecol. 2022 Oct;91(10):2074-2086. doi: 10.1111/1365-2656.13785. Epub 2022 Aug 15.
Studies on humans indicate that encountering multiple sources of adversity in childhood increases the risk of poor long-term health and premature death. Far less is known about cumulative effects of adversity during early life in wildlife. Focusing on the spotted hyena Crocuta crocuta, a social mammal with small litters, extensive maternal care, slow development and access to resources determined by social rank, we determined the contribution of ecological, maternal, social and demographic factors during early life on performance and fitness, and tested whether the impact of early-life adversity is cumulative. Using longitudinal data from 666 female hyenas in the Serengeti National Park, we determined the early growth rate, survival to adulthood, age at first reproduction (AFR), lifetime reproductive success (LRS) and longevity. We fitted multivariate models in which we tested the effects of environmental factors on these performance measures. We then constructed a cumulative adversity index and fitted models to test the effect of this index on each performance measure. Finally, the value of cumulative adversity models was tested by comparing them to multivariate and single-effect models in which the effect of each environmental factor was considered separately. High maternal rank decreased the AFR of daughters. Singleton and dominant cubs had higher growth rate than subordinate cubs, and singletons also had a higher survival chance to adulthood than subordinates. Daughters of prime age mothers had a higher growth rate, longevity and LRS. Little and heavy rainfall decreased survival to adulthood. Increasing numbers of lactating female clan members decreased growth rate, survival to adulthood and LRS. Cumulative adversity negatively affected short-term performance and LRS. Multivariate models outperformed cumulative adversity and single-effect models for all measures except for AFR and longevity, for which single-effect models performed better. Our results suggest that in some wildlife populations the combination of specific conditions in early life may matter more than the accumulation of adverse conditions as such.
对人类的研究表明，童年时期遭遇多种逆境会增加长期健康状况不佳和早逝的风险。野生动物在生命早期经历逆境的累积效应则知之甚少。本研究以斑点鬣狗（Crocuta crocuta）为研究对象，这是一种社会哺乳动物，具有产仔数少、母性抚育时间长、生长发育缓慢和资源获取取决于社会等级等特点。我们确定了生命早期的生态、母性、社会和人口统计学因素对表现和适应性的贡献，并检验了早期逆境的影响是否具有累积性。我们利用塞伦盖蒂国家公园（Serengeti National Park）666 只雌性斑点鬣狗的纵向数据，确定了早期增长率、成年存活率、首次繁殖年龄（age at first reproduction，AFR）、终生繁殖成功率（lifetime reproductive success，LRS）和寿命。我们拟合了多元模型，检验了环境因素对这些表现指标的影响。然后，我们构建了一个累积逆境指数，并拟合模型以检验该指数对每个表现指标的影响。最后，通过将累积逆境模型与多元模型和单因素模型进行比较，检验了累积逆境模型的有效性，其中分别考虑了每个环境因素的影响。较高的母性等级降低了女儿的 AFR。独生子和优势幼崽的生长速度高于从属幼崽，独生子的成年存活率也高于从属幼崽。处于最佳生育年龄的母犬幼崽具有更高的生长速度、寿命和 LRS。降雨量少和降雨量多都会降低成年存活率。哺乳期雌性族群成员数量的增加会降低生长速度、成年存活率和 LRS。累积逆境对短期表现和 LRS 有负面影响。对于除 AFR 和寿命外的所有指标，多元模型的表现都优于累积逆境和单因素模型，而单因素模型在 AFR 和寿命指标上的表现更好。我们的研究结果表明，在某些野生动物种群中，早期生活中特定条件的组合可能比逆境的积累更重要。
