HOST-PARASITE GENETIC INTERACTIONS AND VIRULENCE-TRANSMISSION RELATIONSHIPS IN NATURAL POPULATIONS OF MONARCH BUTTERFLIES
HOST-PARASITE GENETIC INTERACTIONS AND VIRULENCE-TRANSMISSION RELATIONSHIPS IN NATURAL POPULATIONS OF MONARCH BUTTERFLIES
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DOI：
10.1111/j.1558-5646.2009.00845.x
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发表时间：
2010-02-01
期刊：
影响因子：
3.3
通讯作者：
Altizer, Sonia
中科院分区：
文献类型：
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作者：
de Roode, Jacobus C.;Altizer, Sonia
进化模型预测，寄生虫的毒力(寄生虫诱导的宿主死亡)可以作为自然选择作用于宿主间寄生虫传播的结果而进化。两个主要假设是，毒力和传播是遗传相关的，寄生虫基因类型之间的相对毒力和传播保持相似。我们用来自北美东部和西部两个种群的帝王蝶及其原生动物寄生虫进行了交叉感染实验。我们测试了10个寄主家系对18种寄生虫基因型的抗性，并测量了毒力(寄主寿命)和寄生虫传播潜力(孢子载量)。与毒力进化理论一致，我们发现毒力与寄生虫基因型间的传播呈正相关。然而，不同寄主家系的致病力绝对值和传播性绝对值不同，沿着致病力-传播性关系的寄生无性系的等级顺序也不同。种群水平的分析表明，来自北美西部的寄生虫造成了更高的感染水平和毒力，但没有证据表明寄生虫在共域宿主上的局部适应。总而言之，我们的结果表明，宿主基因类型可以影响自然种群中毒力选择的强度和方向，预测毒力进化可能需要在更简单的权衡模型中建立特定于基因型的交互作用。
Evolutionary models predict that parasite virulence (parasite-induced host mortality) can evolve as a consequence of natural selection operating on between-host parasite transmission. Two major assumptions are that virulence and transmission are genetically related and that the relative virulence and transmission of parasite genotypes remain similar across host genotypes. We conducted a cross-infection experiment using monarch butterflies and their protozoan parasites from two populations in eastern and western North America. We tested each of 10 host family lines against each of 18 parasite genotypes and measured virulence (host life span) and parasite transmission potential (spore load). Consistent with virulence evolution theory, we found a positive relationship between virulence and transmission across parasite genotypes. However, the absolute values of virulence and transmission differed among host family lines, as did the rank order of parasite clones along the virulence-transmission relationship. Population-level analyses showed that parasites from western North America caused higher infection levels and virulence, but there was no evidence of local adaptation of parasites on sympatric hosts. Collectively, our results suggest that host genotypes can affect the strength and direction of selection on virulence in natural populations, and that predicting virulence evolution may require building genotype-specific interactions into simpler trade-off models.