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中适合度损失存在差异的现象。近交个体通常较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，或是细胞的胁迫防御机制突破了生物体的生理极限。本研究以食籽甲虫Callosobruchus maculatus为实验材料，选取温度与饲养寄主两个发育胁迫程度存在差异的环境维度，探究近交-环境互作效应。研究发现，近交衰退（inbreeding depression，即近交负荷L）随环境胁迫程度升高而增强，胁迫强度可解释高达66%的近交衰退变异。L与发育胁迫间的上述关联，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、涉及胁迫与近交衰退的现有研究数据开展了元分析（meta-analysis）。元分析结果证实，环境对近交衰退的影响与胁迫强度呈线性比例关系；平均而言，胁迫环境每诱导33%的适合度降低，种群便会额外增加一个致死当量（lethal equivalent）。