发表机构
Univ. Brest, CNRS UMR 6205, Laboratoire de Mathematiques de Bretagne Atlantique; BioSP, INRAE; Department of Ecology & Evolutionary Biology, University of Toronto（布雷斯特大学; 法国国家农业食品与环境研究院; 多伦多大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究揭示有限无性种群在快速环境变化下因丢失最优祖先性状而承受额外适应度负荷，显著阻碍其存续，区别于遗传漂变。
AI 中文摘要
种群的适应动态受其繁殖模式影响。个体是否进行有性生殖或无性生殖，对变化环境中种群的存续和灭绝可能产生重大影响。经典理论通过遗传方差解释这种依赖性，而未进一步考虑根本不同的遗传模式。近年来的理论进展捕捉了这些机制，强调它们如何戏剧性地改变渐变环境中适应的本质。在此，我们表明这些假设无限种群大小的最新预测，在环境变化迅速时，对有限无性种群的命运过于乐观。这是因为无限无性种群中的每个个体都源自一个曾经最优的祖先，而在种群中找到该最优个体的可能性随种群规模迅速下降。为预测有限无性种群的命运，我们推导了平衡表型分布，假设不存在超出某个未知性状的个体。正如预期，我们发现当表型分布包含最优性状时，种群的命运与先前预测一致。然而，当最优性状丢失时，会产生额外的适应度负荷。我们进一步推导了祖先谱系典型轨迹的预测，这解释了额外负荷：所有个体都源自携带最适性状（可能为次优）的共同祖先。我们的工作揭示了一种特定于无性适应且不同于遗传漂变的有限种群效应，该效应显著阻碍了小型无性种群在变化环境中存续的能力。
英文摘要
The dynamics of adaptation in a population are informed by its mode of reproduction. Whether individuals reproduce sexually or asexually, then, can have large effects on population persistence and extinction in changing environments. Classical theory explains this dependence via genetic variance without further accounting for a fundamentally different mode of inheritance. Recent theoretical advances capture these mechanisms, highlighting how they dramatically change the nature of adaptation in gradually changing environments. Here we show that these recent predictions, which assume infinite-population sizes, are overly optimistic about the fate of finite asexual populations when environmental change is rapid. This is because every individual in an infinite asexual population descends from a once optimal ancestor and the likelihood of finding this optimal individual in the population declines rapidly with population size. To predict the fate of finite asexual populations we derive the equilibrium phenotypic distribution assuming there exist no individuals beyond some unknown trait. As expected, we find that when the phenotypic distribution contains the optimal trait, the population's fate is consistent with previous predictions. When the optimal trait is lost, however, an additional fitness load is incurred. We further derive a prediction for the typical trajectory of an ancestral lineage, which explains the additional load: all individuals descend from a common ancestor carrying the fittest trait, which may be suboptimal. Our work uncovers a finite-population effect that is specific to asexual adaptation and distinct from genetic drift, which significantly hinders the ability of small asexual populations to persist in changing environments.
