The evolution of parasite host range in heterogeneous host populations
The evolution of parasite host range in heterogeneous host populations
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DOI：
10.1111/jeb.13608
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发表时间：
2020-02
影响因子：
2.1
通讯作者：
A. Gibson;Helena Baffoe-Bonnie;McKenna J. Penley;Julie Lin;Raythe Owens;Arooj Khalid;Levi T. Morran
中科院分区：
文献类型：
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作者：
A. Gibson;Helena Baffoe-Bonnie;McKenna J. Penley;Julie Lin;Raythe Owens;Arooj Khalid;Levi T. Morran
生态位宽度演化理论认为，资源异质性对生态位宽度进行选择。对于寄生虫，这一理论预测，寄生虫种群将演变，或保持，更广泛的主机范围时，选择在遗传多样性的主机人口相对于同质的主机人口。为了检验这一预测，我们选择了细菌寄生虫粘质沙雷氏菌杀死秀丽隐杆线虫在遗传异质性（50%混合的两个实验基因型）或同质（100%的基因型）的人口。经过20轮的选择，我们比较了选定的寄生虫的宿主范围，通过测量寄生虫的健身（即毒力，选定的健身性状）的两个焦点主机基因型和一个新的主机基因型。正如预测的那样，异质性宿主种群选择的寄生虫具有更广泛的宿主范围：这些寄生虫种群获得或保持所有宿主基因型的毒力。这一结果与选择在同质群体的一个主机基因型。在这里，主机范围收缩，寄生虫种群获得的焦点主机基因型和失去新的主机基因型的毒力。然而，这种模式是不重复的第二个主机基因型的同质群体中的选择：这些寄生虫种群没有获得的焦点主机基因型的毒力，也没有失去对新的主机基因型的毒力。我们的研究结果表明，宿主异质性可以维持更广泛的寄生虫种群的宿主范围。然而，个体宿主基因型在选择寄生虫种群专业化的程度上各不相同。
Theory on the evolution of niche width argues that resource heterogeneity selects for niche breadth. For parasites, this theory predicts that parasite populations will evolve, or maintain, broader host ranges when selected in genetically diverse host populations relative to homogeneous host populations. To test this prediction, we selected the bacterial parasite Serratia marcescens to kill Caenorhabditis elegans in populations that were genetically heterogeneous (50% mix of two experimental genotypes) or homogeneous (100% of either genotype). After 20 rounds of selection, we compared the host range of selected parasites by measuring parasite fitness (i.e. virulence, the selected fitness trait) on the two focal host genotypes and on a novel host genotype. As predicted, heterogeneous host populations selected for parasites with a broader host range: these parasite populations gained or maintained virulence on all host genotypes. This result contrasted with selection in homogeneous populations of one host genotype. Here, host range contracted, with parasite populations gaining virulence on the focal host genotype and losing virulence on the novel host genotype. This pattern was not, however, repeated with selection in homogeneous populations of the second host genotype: these parasite populations did not gain virulence on the focal host genotype, nor did they lose virulence on the novel host genotype. Our results indicate that host heterogeneity can maintain broader host ranges in parasite populations. Individual host genotypes, however, vary in the degree to which they select for specialization in parasite populations.