NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, United Kingdom.
Evolution. 2012 Jun;66(6):1985-90. doi: 10.1111/j.1558-5646.2011.01559.x. Epub 2012 Jan 23.
The ecological forces shaping adaptive radiations are of great interest to evolutionary ecologists. Here, we experimentally test the hypothesis that the diversification of a lineage should be limited in the presence of competition from another taxon. We do this by studying a model microbial adaptive radiation (the generation of phenotypic diversity in asexual lineages of the bacterium Pseudomonas fluorescens) in the presence or absence of a competitor (Pseudomonas putida). In a spatially heterogeneous environment, the competitor P. putida reduced P. fluorescens population size only slightly and had no effect on diversification. In a spatially homogeneous environment, the competitor reduced P. fuoresecens population size to a much greater extent. Again the final extent of diversification in P. fluorescens was not affected by the competitor, but early diversification was accelerated. In this environment, P. putida suppressed the growth of a common variant of P. fluorescens and directly or indirectly facilitated the growth of a rare morph. Our results suggest that competition experienced by diversifying lineages may have complex effects on adaptive radiations not fully captured by current theory.
塑造适应性辐射的生态力量引起了进化生态学家的极大兴趣。在这里，我们通过实验检验了这样一种假设，即在来自另一分类单元的竞争存在的情况下，谱系的多样化应该受到限制。我们通过在存在或不存在竞争者（恶臭假单胞菌）的情况下研究模型微生物适应性辐射（在无性谱系的荧光假单胞菌中产生表型多样性）来实现这一点。在空间异质环境中，竞争者恶臭假单胞菌仅略微降低了荧光假单胞菌的种群规模，对多样化没有影响。在空间均匀的环境中，竞争者大大降低了荧光假单胞菌的种群规模。同样，荧光假单胞菌的最终多样化程度不受竞争者的影响，但早期多样化得到了加速。在这种环境下，恶臭假单胞菌抑制了荧光假单胞菌常见变体的生长，并直接或间接地促进了稀有形态的生长。我们的结果表明，正在分化的谱系所经历的竞争可能对适应性辐射产生复杂的影响，而当前的理论并不能完全捕捉到这些影响。
