Data from: Spatial structure of ecological opportunity drives adaptation in a bacterium

Abundant ecological opportunity is thought to drive adaptation and diversification. The presence of multiple opportunities leads to divergent selection, which can slow adaptation when niche-specific beneficial mutations have antagonistically pleiotropic effects. Alternately, competition for multiple opportunities can generate divergent selection leading to high rates of adaptive differentiation. Which outcome occurs may depend on the spatial structure of those ecological opportunities. In a mixture of resources, competition for multiple opportunities can drive divergent selection; however if each resource is available in a spatially distinct patch, competition for multiple opportunities simultaneously cannot occur. We report the effects of extent and spatial structure of ecological opportunity on the evolutionary dynamics of populations of Pseudomonas fluorescens over 1000 generations. We varied extent of ecological opportunity by varying the number of sugar resources (mannose, glucose, and xylose), and varied spatial structure by providing resources in either mixtures, or spatially distinct patches. We saw that a particularly novel resource (xylose) drove the rate of adaptation when in a mixture but had no effect on diversity. Instead we saw the evolution of a single adaptive strategy that differed with respect to phenotype and degree of specialization, depending on both the extent and spatial structure of ecological opportunity.学界普遍认为，充足的生态机会（ecological opportunity）可推动生物的适应性演化与多样化进程。当生态位特异性的有益突变存在拮抗多效性（antagonistic pleiotropy）时，多重生态机会的存在会引发分歧选择，进而延缓适应性演化速率。反之，对多重生态机会的竞争亦可引发分歧选择，进而带来高速率的适应性分化。最终出现何种结果，取决于这些生态机会的空间结构。在资源混合的情境中，对多重生态机会的竞争可驱动分歧选择；但若每种资源仅分布于空间上独立的斑块中，则无法同时出现针对多重生态机会的竞争。本研究探讨了生态机会的广度与空间结构对荧光假单胞菌（Pseudomonas fluorescens）种群在1000代演化过程中的动态影响。我们通过调整糖类资源的数量（甘露糖、葡萄糖与木糖）来调控生态机会的广度，并通过将资源设置为混合分布或空间独立斑块两种形式，来改变实验的空间结构。实验结果显示，当资源以混合形式存在时，一种较为新颖的资源（木糖，xylose）会主导适应性演化速率，但对种群多样性无显著影响。与之相对的是，我们观察到仅演化出一类适应性策略，其表型与特化程度会因生态机会的广度及空间结构的不同而产生差异。