Time and Chance: Using Age Partitioning to Understand How Luck Drives Variation in Reproductive Success
Time and Chance: Using Age Partitioning to Understand How Luck Drives Variation in Reproductive Success
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DOI：
10.1086/712874
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发表时间：
2021-04-01
影响因子：
2.9
通讯作者：
Hooker, Giles
中科院分区：
文献类型：
--
作者：
Snyder, Robin E.;Ellner, Stephen P.;Hooker, Giles
在个体的一生中，运气通常可以解释一个群体中寿命或终生生殖产出（LRO）的个体间变异的很大一部分，而个体特征或“质量”的变异解释得少得多。为了理解运气如何、在生命周期的何处以及通过哪些人口统计过程胜过特征变异，我们展示了如何按年龄划分运气和性状变异对LRO方差的贡献，以及如何量化运气的三个不同成分。我们将这些工具应用于几个实证案例研究。我们发现，运气沼泽性状变异的影响，在所有年龄段，主要是因为在个人状态动态（“状态轨迹运气”）的随机性。人生早期的运气是最重要的。非常早期的状态轨迹运气通常决定了一个个体是否会繁殖，可能是通过确保他们不会很快死亡或注定失败。在那些至少繁殖一次的品种中，早期运气的减少导致了成功率的变化。因此，运气的重要性往往在生命的早期有一个尖锐的高峰，或者有两个高峰。我们建议，年龄或阶段的重要性运气峰值是潜在的目标干预措施，以造福于关注的人群，不同的特征值弹性分析确定的。
Over the course of individual lifetimes, luck usually explains a large fraction of the between-individual variation in life span or lifetime reproductive output (LRO) within a population, while variation in individual traits or "quality" explains much less. To understand how, where in the life cycle, and through which demographic processes luck trumps trait variation, we show how to partition by age the contributions of luck and trait variation to LRO variance and how to quantify three distinct components of luck. We apply these tools to several empirical case studies. We find that luck swamps effects of trait variation at all ages, primarily because of randomness in individual state dynamics ("state trajectory luck"). Luck early in life is most important. Very early state trajectory luck generally determines whether an individual ever breeds, likely by ensuring that they are not dead or doomed quickly. Less early luck drives variation in success among those breeding at least once. Consequently, the importance of luck often has a sharp peak early in life or it has two peaks. We suggest that ages or stages where the importance luck peaks are potential targets for interventions to benefit a population of concern, different from those identified by eigenvalue elasticity analysis.