Abstract Temperature determines the rates of all biochemical and biophysical processes, and is also believed to be a key driver of macroevolutionary patterns. It is suggested that physiological constraints at low temperatures may diminish the fitness advantages of otherwise beneficial mutations; by contrast, relatively high, benign, temperatures allow beneficial mutations to efficiently show their phenotypic effects. To experimentally test this “mutational effects” mechanism, we examined the fitness effects of mutations across a temperature gradient using bacterial genotypes from the early stage of a mutation accumulation experiment with Escherichia coli. While the incidence of beneficial mutations did not significantly change across environmental temperatures, the number of mutations that conferred strong beneficial fitness effects was greater at higher temperatures. The results therefore support the hypothesis that warmer temperatures increase the chance and magnitude of positive selection, with implications for explaining the geographic patterns in evolutionary rates and understanding contemporary evolution under global warming.

中文翻译：

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温暖的温度增强了有益的突变效应


摘要 温度决定所有生化和生物物理过程的速率，也被认为是宏观进化模式的关键驱动因素。有人认为，低温下的生理限制可能会削弱原本有益的突变的适应性优势；相比之下，相对较高、良性的温度允许有益的突变有效地显示其表型效应。为了通过实验测试这种“突变效应”机制，我们使用大肠杆菌突变积累实验早期阶段的细菌基因型，检查了温度梯度上突变的适应性效应。虽然有益突变的发生率在不同环境温度下并没有显着变化，但在较高温度下，赋予强有益适应性效果的突变数量会更多。因此，结果支持这样的假设：气温升高会增加正选择的机会和程度，这对于解释进化速率的地理模式和理解全球变暖下的当代进化具有重要意义。