Rainey P B, Travisano M
Department of Plant Sciences, University of Oxford, UK.
Nature. 1998 Jul 2;394(6688):69-72. doi: 10.1038/27900.
Successive adaptive radiations have played a pivotal role in the evolution of biological diversity. The effects of adaptive radiation are often seen, but the underlying causes are difficult to disentangle and remain unclear. Here we examine directly the role of ecological opportunity and competition in driving genetic diversification. We use the common aerobic bacterium Pseudomonas fluorescens, which evolves rapidly under novel environmental conditions to generate a large repertoire of mutants. When provided with ecological opportunity (afforded by spatial structure), identical populations diversify morphologically, but when ecological opportunity is restricted there is no such divergence. In spatially structured environments, the evolution of variant morphs follows a predictable sequence and we show that competition among the newly evolved niche-specialists maintains this variation. These results demonstrate that the elementary processes of mutation and selection alone are sufficient to promote rapid proliferation of new designs and support the theory that trade-offs in competitive ability drive adaptive radiation.
连续的适应性辐射在生物多样性的进化中发挥了关键作用。适应性辐射的影响常常可见，但其根本原因却难以厘清，仍不明确。在这里，我们直接研究生态机遇和竞争在推动基因多样化方面的作用。我们使用常见的需氧细菌荧光假单胞菌，它在新的环境条件下能快速进化，产生大量的突变体。当提供生态机遇（由空间结构提供）时，相同的种群会在形态上发生分化，但当生态机遇受到限制时，就不会出现这种分化。在空间结构环境中，变异形态的进化遵循可预测的序列，并且我们表明新进化出的生态位专家之间的竞争维持了这种变异。这些结果表明，仅突变和选择的基本过程就足以促进新设计的快速增殖，并支持竞争能力的权衡驱动适应性辐射这一理论。
