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 100875, People's Republic of China
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 100875, People's Republic of China.
Proc Biol Sci. 2018 Sep 5;285(1886):20181515. doi: 10.1098/rspb.2018.1515.
The warmer regions harbour more species, attributable to accelerated speciation and increased ecological opportunities for coexistence. While correlations between temperature and energy availability and habitat area have been suggested as major drivers of these biodiversity patterns, temperature can theoretically also have direct effects on the evolution of diversity. Here, we experimentally studied the evolution of diversity in a model adaptive radiation of the bacterium across a temperature gradient. Diversification increased at higher temperatures, driven by both faster generation of genetic variation and stronger diversifying selection. Specifically, low temperatures could limit the generation of diversity, suggested by the observation that supply of genetic variation through immigration increased diversity at low, but not high temperatures. The two major determinants of mutation supply, population size and mutation rate, both showed a positive temperature dependence. Stronger diversifying selection in warmer environments was suggested by promoted coexistence, and further explicitly inferred by the ability of evolved phenotypes to invade the ancestral type from rare. We discuss possible physiological and environmental mechanisms underlying the findings, most of which are likely to be general.
温暖的地区拥有更多的物种，这归因于加速的物种形成和共存的生态机会增加。虽然已经有人提出温度与能量供应和栖息地面积之间的相关性是这些生物多样性模式的主要驱动因素，但温度理论上也可以对多样性的进化产生直接影响。在这里，我们在细菌的模型适应性辐射中跨温度梯度进行了实验研究，以研究多样性的进化。多样性在较高温度下增加，这是由遗传变异的更快产生和更强的分化选择驱动的。具体来说，低温可能会限制多样性的产生，这一点从通过移民供应遗传变异可以增加低温下的多样性而不是高温下的多样性这一观察结果中得到了证明。供应变异的两个主要决定因素——种群大小和突变率——都表现出正的温度依赖性。温暖环境中的更强的分化选择表明了共存的促进作用，并且通过从稀有中进化出的表型能够入侵祖先类型的能力进一步明确地推断出来。我们讨论了这些发现背后可能存在的生理和环境机制，其中大多数可能是普遍存在的。
