The role of parasites in sympatric and allopatric host diversification
The role of parasites in sympatric and allopatric host diversification
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DOI：
10.1038/nature01164
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发表时间：
2002-12-05
期刊：
影响因子：
64.8
通讯作者：
Rainey, PB
中科院分区：
文献类型：
--
作者：
Buckling, A;Rainey, PB
剥削者（寄生虫和捕食者）被认为在宿主或猎物的多样化以及最终的物种形成中发挥着重要作用(1-3)。如果存在多种剥削者抵抗策略或与剥削者抵抗相关的适应成本，剥削者可能会推动同域（群体内）多样化（4-8）。剥削者还可能通过创造不同的选择压力和增加随机分歧率来推动异域（种群间）多样化(9,10)。我们研究了剧毒病毒寄生虫（噬菌体）对空间结构微观世界中荧光假单胞菌细菌多样化的影响 (11)。在这里，我们表明，在没有噬菌体的情况下，细菌迅速多样化为空间生态位专家，在复制群体中具有相似的多样性模式。在噬菌体存在的情况下，由于噬菌体导致宿主密度减少，从而减少了对资源的竞争，同域多样性大大减少。相比之下，由于噬菌体强加的抗性选择，异域多样性大大增加，这导致种群遵循不同的进化轨迹。这些结果表明，剥削者可以推动种群之间的多样化，但可能会通过反对资源竞争产生的多样化选择来抑制种群内部的多样化。
Exploiters (parasites and predators) are thought to play a significant role in diversification, and ultimately speciation, of their hosts or prey(1-3). Exploiters may drive sympatric (within-population) diversification if there are a variety of exploiter-resistance strategies or fitness costs associated with exploiter resistance(4-8). Exploiters may also drive allopatric (between-population) diversification by creating different selection pressures and increasing the rate of random divergence(9,10). We examined the effect of a virulent viral parasite (phage) on the diversification of the bacterium Pseudomonas fluorescens in spatially structured microcosms(11). Here we show that in the absence of phages, bacteria rapidly diversified into spatial niche specialists with similar patterns of diversity across replicate populations. In the presence of phages, sympatric diversity was greatly reduced, as a result of phage-imposed reductions in host density decreasing competition for resources. In contrast, allopatric diversity was greatly increased as a result of phage-imposed selection for resistance, which caused populations to follow divergent evolutionary trajectories. These results show that exploiters can drive diversification between populations, but may inhibit diversification within populations by opposing diversifying selection that arises from resource competition.