Department of Zoology, University of Oxford, Oxford, UK.
J Evol Biol. 2012 Jan;25(1):187-95. doi: 10.1111/j.1420-9101.2011.02416.x. Epub 2011 Nov 17.
Spatial abiotic heterogeneity can result in divergent selection, hence might increase the magnitude of host-parasite local adaptation (the mean difference in fitness of sympatric vs. allopatric host-parasite combinations). We explicitly tested this hypothesis by measuring local adaptation in experimentally coevolved populations of bacteria and viruses evolved in the same or different nutrient media. Consistent with previous work, we found that mean levels of evolved phage infectivity and bacteria resistance varied with nutrient concentration, with maximal levels at nutrient concentrations that supported the greatest densities of bacteria. Despite this variation in evolved mean infectivity and resistance between treatments, we found that parasite local adaptation was greatly increased when measured between populations evolved in different, compared with the same, media. This pattern is likely to have resulted from different media imposing divergent selection on bacterial hosts, and phages in turn adapting to their local hosts. These results demonstrate that the abiotic environment can play a strong and predictable role in driving patterns of local adaptation.
空间非生物异质性会导致分歧选择，从而可能增加宿主-寄生虫局部适应的幅度（同域与异域宿主-寄生虫组合之间适应度的平均差异）。我们通过测量在相同或不同营养介质中进化的细菌和病毒的实验共进化种群中的局部适应，明确地检验了这一假设。与先前的工作一致，我们发现，噬菌体感染性和细菌抗性的平均水平随营养浓度而变化，在支持细菌密度最大的营养浓度下达到最大值。尽管在不同处理之间，进化后的平均感染性和抗性存在差异，但我们发现，当在不同的培养基中进化的种群之间进行寄生虫局部适应测量时，寄生虫的局部适应程度大大增加。这种模式可能是由于不同的培养基对细菌宿主施加了不同的选择压力，而噬菌体则反过来适应了它们的本地宿主。这些结果表明，非生物环境可以在驱动局部适应模式方面发挥强大而可预测的作用。
