Antagonistic coevolution with parasites increases the cost of host deleterious mutations
Antagonistic coevolution with parasites increases the cost of host deleterious mutations
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DOI：
10.1098/rspb.2005.3279
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发表时间：
2006-01-07
影响因子：
4.7
通讯作者：
Hochberg, ME
中科院分区：
文献类型：
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作者：
Buckling, A;Wei, Y;Hochberg, ME
当个体被寄生时，有害突变的适应性后果有时会更大，因此寄生虫可能会导致更快地从宿主种群中清除有害突变。当宿主和寄生虫拮抗性共同进化（宿主抗性和寄生虫感染性的相互进化）时，宿主有害突变的意义以前没有被实验研究过。我们通过在实验室微观世界中共同进化细菌荧光假单胞菌和寄生噬菌体来解决这个问题，使用具有高和低突变负荷的细菌。细菌耐药性和噬菌体感染性之间的定向协同进化发生在所有人群中。细菌种群的适应性，通过竞争实验与祖先的基因型在噬菌体的情况下，下降所花费的时间共同进化。然而，这种下降在具有高突变负荷的细菌中显著更快，这表明细菌对噬菌体的抗性的成本在有害突变的存在下更大（协同上位性）。因此，在存在高突变负荷的情况下，对噬菌体的抗性的进化成本更高。与这些数据相一致，具有高突变负荷的细菌与其噬菌体群体进行了不太快速的定向共进化，并且对其共进化的噬菌体群体表现出较低水平的抗性。这些数据表明，与寄生虫的共同进化增加了有害突变从宿主种群中清除的速度。
The fitness consequences of deleterious mutations are sometimes greater when individuals are parasitized, hence parasites may result in the more rapid purging of deleterious mutations from host populations. The significance of host deleterious mutations when hosts and parasites antagonistically coevolve (reciprocal evolution of host resistance and parasite infectivity) has not previously been experimentally investigated. We addressed this by coevolving the bacterium Pseudomonas fluorescens and a parasitic bacteriophage in laboratory microcosms, using bacteria with high and low mutation loads. Directional coevolution between bacterial resistance and phage infectivity occurred in all populations. Bacterial population fitness, as measured by competition experiments with ancestral genotypes in the absence of phage, declined with time spent coevolving. However, this decline was significantly more rapid in bacteria with high mutation loads, suggesting the cost of bacterial resistance to phage was greater in the presence of deleterious mutations (synergistic epistasis). As such, resistance to phage was more costly to evolve in the presence of a high mutation load. Consistent with these data, bacteria with high mutation loads underwent less rapid directional coevolution with their phage populations, and showed lower levels of resistance to their coevolving phage populations. These data suggest that coevolution with parasites increases the rate at which deleterious mutations are purged from host populations.