Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.
Institute of Botany and Landscape Ecology, University of Greifswald, Greifswald, Germany.
Heredity (Edinb). 2021 Jan;126(1):23-37. doi: 10.1038/s41437-020-0338-4. Epub 2020 Jul 6.
Assessing the genetic adaptive potential of populations and species is essential for better understanding evolutionary processes. However, the expression of genetic variation may depend on environmental conditions, which may speed up or slow down evolutionary responses. Thus, the same selection pressure may lead to different responses. Against this background, we here investigate the effects of thermal stress on genetic variation, mainly under controlled laboratory conditions. We estimated additive genetic variance (V), narrow-sense heritability (h) and the coefficient of genetic variation (CV) under both benign control and stressful thermal conditions. We included six species spanning a diverse range of plant and animal taxa, and a total of 25 morphological and life-history traits. Our results show that (1) thermal stress reduced fitness components, (2) the majority of traits showed significant genetic variation and that (3) thermal stress affected the expression of genetic variation (V, h or CV) in only one-third of the cases (25 of 75 analyses, mostly in one clonal species). Moreover, the effects were highly species-specific, with genetic variation increasing in 11 and decreasing in 14 cases under stress. Our results hence indicate that thermal stress does not generally affect the expression of genetic variation under laboratory conditions but, nevertheless, increases or decreases genetic variation in specific cases. Consequently, predicting the rate of genetic adaptation might not be generally complicated by environmental variation, but requires a careful case-by-case consideration.
评估种群和物种的遗传适应潜力对于更好地理解进化过程至关重要。然而，遗传变异的表达可能取决于环境条件，这可能会加速或减缓进化反应。因此，相同的选择压力可能会导致不同的反应。在此背景下，我们在这里研究热应激对遗传变异的影响，主要是在受控的实验室条件下。我们估计了在良性对照和应激热条件下的加性遗传方差 (V)、狭义遗传力 (h) 和遗传变异系数 (CV)。我们包括了六个跨越植物和动物类群多样化范围的物种，总共 25 个形态和生活史特征。我们的结果表明：(1) 热应激降低了适应度成分；(2) 大多数特征表现出显著的遗传变异；(3) 热应激仅在三分之一的情况下（75 次分析中的 25 次，主要在一个克隆物种中）影响遗传变异的表达（V、h 或 CV）。此外，这些影响具有高度的物种特异性，在 11 个案例中遗传变异增加，在 14 个案例中减少。因此，我们的结果表明，热应激通常不会在实验室条件下影响遗传变异的表达，但在特定情况下会增加或减少遗传变异。因此，预测遗传适应的速度可能不会被环境变化普遍复杂化，但需要逐个案例进行仔细考虑。
