The effects of competition and predation on diversification in a model adaptive radiation
The effects of competition and predation on diversification in a model adaptive radiation
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DOI：
10.1038/nature05599
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发表时间：
2007-03-22
期刊：
影响因子：
64.8
通讯作者：
Kassen, Rees
中科院分区：
文献类型：
--
作者：
Meyer, Justin R.;Kassen, Rees
许多生命的多样性被认为是通过连续几轮的适应性辐射产生的——一个谱系迅速多样化为一系列生态和表型上不同的物种（1-3）。资源竞争和捕食都被认为是驱动这一过程的机制（4,5），尽管前者比后者研究得更好（6,7）。在这里，我们通过实验展示了原生生物（嗜热四膜虫）的捕食如何影响细菌猎物荧光假单胞菌（Pseudomonas fluorescens）的模型适应性辐射的多样化。我们估计了在存在和不存在捕食者的情况下，竞争的生态位专家猎物的频率依赖适应度函数，并用这些函数来检验关于多样化程度（以新基因型的数量来衡量）和多样化率的假设。竞争和捕食各自产生了多样化的选择，我们表明，这种选择能够推动猎物多样化到相似的程度，但速度不同，多样化在捕食者存在时明显延迟。这种延迟的原因是由于捕食造成的猎物密度的减少而导致多样化选择的减弱。我们的研究结果表明，捕食可能在驱动适应性辐射方面发挥了未被充分认识的作用。
Much of life's diversity is thought to have arisen through successive rounds of adaptive radiation - the rapid diversification of a lineage into a range of ecologically and phenotypically distinct species(1-3). Both resource competition and predation have been suggested as mechanisms driving this process(4,5), although the former is better studied than the latter(6,7). Here we show experimentally how predation by a protist, Tetrahymena thermophila, affects diversification in a model adaptive radiation of the bacterial prey, Pseudomonas fluorescens. We estimate the frequency-dependent fitness functions of competing niche-specialist prey in the presence and absence of predation, and use these to test hypotheses about the extent ( measured as the number of new genotypes) and rate of diversification. Competition and predation independently generated diversifying selection that we show is capable of driving prey diversification to similar extents but at different rates, diversification being markedly delayed in the presence of predators. The cause of this delay stems from weaker diversifying selection due to the reduction in prey density caused by predation. Our results suggest that predation may play an under-appreciated role in driving adaptive radiations.