Chu Xiao-Lin, Zhang Da-Yong, Buckling Angus, Zhang Quan-Guo
State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China.
ESI & CEC, Biosciences, University of Exeter, Penryn, UK.
J Evol Biol. 2020 Aug;33(8):1020-1027. doi: 10.1111/jeb.13642. Epub 2020 Jun 23.
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.
温度决定了所有生物化学和生物物理过程的速率，并且也被认为是宏观进化模式的关键驱动因素。有人提出，低温下的生理限制可能会削弱其他有益突变的适应性优势；相比之下，相对较高的适宜温度能使有益突变有效地展现其表型效应。为了通过实验验证这种“突变效应”机制，我们利用来自大肠杆菌突变积累实验早期阶段的细菌基因型，研究了跨温度梯度的突变的适应性效应。虽然有益突变的发生率在不同环境温度下没有显著变化，但在较高温度下，具有强烈有益适应性效应的突变数量更多。因此，这些结果支持了这样的假说，即较高温度增加了正选择的机会和幅度，这对于解释进化速率的地理模式以及理解全球变暖下的当代进化具有重要意义。
