Departament de Genètica i de Microbiologia, Grup de Biologia Evolutiva (GBE), Universitat Autònoma de Barcelona 08193, Bellaterra, Barcelona, Spain.
Ecol Evol. 2012 Nov;2(11):2866-80. doi: 10.1002/ece3.385. Epub 2012 Oct 13.
The potential of populations to evolve in response to ongoing climate change is partly conditioned by the presence of heritable genetic variation in relevant physiological traits. Recent research suggests that Drosophila melanogaster exhibits negligible heritability, hence little evolutionary potential in heat tolerance when measured under slow heating rates that presumably mimic conditions in nature. Here, we study the effects of directional selection for increased heat tolerance using Drosophila as a model system. We combine a physiological model to simulate thermal tolerance assays with multilocus models for quantitative traits. Our simulations show that, whereas the evolutionary response of the genetically determined upper thermal limit (CTmax) is independent of methodological context, the response in knockdown temperatures varies with measurement protocol and is substantially (up to 50%) lower than for CTmax. Realized heritabilities of knockdown temperature may grossly underestimate the true heritability of CTmax. For instance, assuming that the true heritability of CTmax in the base population is h(2) = 0.25, realized heritabilities of knockdown temperature are around 0.08-0.16 depending on heating rate. These effects are higher in slow heating assays, suggesting that flawed methodology might explain the apparently limited evolutionary potential of cosmopolitan D. melanogaster.
种群对持续气候变化做出反应的潜力部分取决于相关生理特征中存在可遗传的遗传变异。最近的研究表明，黑腹果蝇的耐热性遗传力可忽略不计，因此在以缓慢升温速度（推测与自然界条件相似）进行测量时，其耐热性的进化潜力很小。在这里，我们使用果蝇作为模型系统，研究了增加耐热性的定向选择的影响。我们将一种生理模型与多基因座数量性状模型相结合，以模拟耐热性测定。我们的模拟表明，虽然由遗传决定的上热限（CTmax）的进化反应独立于方法学背景，但击倒温度的反应随测量方案而变化，且比 CTmax 低得多（高达 50%）。击倒温度的现实遗传力可能严重低估 CTmax 的真实遗传力。例如，假设基础种群中 CTmax 的真实遗传力为 h(2) = 0.25，根据加热速度，击倒温度的现实遗传力约为 0.08-0.16。在缓慢的加热试验中，这些影响更高，这表明有缺陷的方法可能解释了普遍存在的黑腹果蝇的耐热性进化潜力似乎有限。
