Data from: Experimental evolution with a multicellular host causes diversification within and between microbial parasite populations – differences in emerging phenotypes of two different parasite strains

Host-parasite coevolution is predicted to have complex evolutionary consequences, potentially leading to the emergence of genetic and phenotypic diversity for both antagonists. However, little is known about variation in phenotypic responses to coevolution between different parasite strains exposed to the same experimental conditions. We infected Caenorhabditis elegans with one of two strains of Bacillus thuringiensis and either allowed the host and the parasite to experimentally coevolve (coevolution treatment) or allowed only the parasite to adapt to the host (one-sided parasite adaptation). By isolating single parasite clones from evolved populations, we found phenotypic diversification of the ancestral strain into distinct clones, which varied in virulence towards ancestral hosts and competitive ability against other parasite genotypes. Parasite phenotypes differed remarkably not only between the two strains, but also between and within different replicate populations, indicating diversification of the clonal population caused by selection. This study highlights that the evolutionary selection pressure mediated by a multicellular host causes phenotypic diversification, but not necessarily with the same phenotypic outcome for different parasite strains.

宿主-寄生虫共进化（Host-parasite coevolution）被预测会引发复杂的进化效应，可能促使宿主与寄生虫这两类拮抗生物产生遗传与表型多样性。然而，目前对于暴露于相同实验条件下的不同寄生虫菌株，其针对共进化的表型响应差异仍知之甚少。本研究将秀丽隐杆线虫（Caenorhabditis elegans）分别接种于两株苏云金芽孢杆菌（Bacillus thuringiensis）中的一株，并设置两类实验处理：一组允许宿主与寄生虫开展实验性共进化（coevolution treatment），另一组仅允许寄生虫进行单向适应（one-sided parasite adaptation）。通过从进化后的种群中分离单个寄生虫克隆体，我们发现祖先菌株的表型分化为多个独特克隆株，这些克隆株对祖先宿主的毒力以及与其他寄生虫基因型的竞争能力均存在差异。寄生虫的表型不仅在两株初始菌株之间存在显著差异，在不同重复种群之间以及同一重复种群内部亦存在显著分化，这表明选择压力引发了克隆种群的表型多样化。本研究表明，由多细胞宿主介导的进化选择压力可导致表型多样化，但不同寄生虫菌株的表型演化结果未必一致。