Data from: Inbreeding depression increases with environmental stress: an experimental study and meta-analysis

Inbreeding-environment interactions occur when inbreeding leads to differential fitness loss in different environments. Inbred individuals are often more sensitive to environmental stress than are outbred individuals, presumably because stress increases the expression of deleterious recessive alleles or cellular safeguards against stress are pushed beyond the organism's physiological limits. We examined inbreeding-environment interactions, along two environmental axes (temperature and rearing host) that differ in the amount of developmental stress they impose, in the seed-feeding beetle Callosobruchus maculatus. We found that inbreeding depression (inbreeding load, L) increased with the stressfulness of the environment, with the magnitude of stress explaining as much as 66% of the variation in inbreeding depression. This relationship between L and developmental stress was not explainable by an increase in phenotypic variation in more stressful environments. To examine the generality of this experimental result, we conducted a meta-analysis of the available data from published studies looking at stress and inbreeding depression. The meta-analysis confirmed that the effect of the environment on inbreeding depression scales linearly with the magnitude of stress; a population suffers one additional lethal equivalent, on average, for each 33% reduction in fitness induced by the stressful environment.近交-环境互作（inbreeding-environment interactions）指近交导致不同环境下适合度出现差异化丧失的现象。近交个体通常比远交个体对环境胁迫更为敏感，推测其机制为：胁迫会提升有害隐性等位基因的表达水平，或是机体对抗胁迫的细胞防御系统被突破了自身生理极限。本研究以食籽甲虫绿豆象（Callosobruchus maculatus）为实验材料，探究了两类环境维度（温度与饲养寄主）下的近交-环境互作，这两类环境所施加的发育胁迫程度存在显著差异。研究结果显示，近交衰退（inbreeding depression，近交载荷L）随环境胁迫强度的升高而增强，胁迫强度可解释高达66%的近交衰退变异。L与发育胁迫之间的这种关联，无法通过高胁迫环境下表型变异的增加来解释。为验证该实验结果的普适性，我们对已发表的胁迫与近交衰退相关研究的公开数据开展了元分析（meta-analysis）。元分析结果证实，环境对近交衰退的影响随胁迫强度呈线性变化；平均而言，胁迫环境每导致种群适合度降低33%，该种群就会额外增加一个致死当量。