Evolution of trophic transmission in parasites: Why add intermediate hosts?
Evolution of trophic transmission in parasites: Why add intermediate hosts?
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DOI：
10.1086/375681
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发表时间：
2003-08-01
影响因子：
2.9
通讯作者：
Thomas, F
中科院分区：
文献类型：
--
作者：
Choisy, M;Brown, SP;Thomas, F
尽管多宿主复杂生命周期（CLC）在几个关系较远的寄生虫群体中很常见，但它们的进化仍然知之甚少。在本文中，我们认为在特定情况下，在单主机生命周期中添加第二个主机可能会增强传播（即到达目标主机）。例如，在某些情况下，利用捕食者物种的寄生虫的繁殖体通过包埋在目标捕食者的猎物中，比通过其他传播模式获得更高的宿主寻找成功率。在这种情况下，选择应该有利于从单宿主生命周期过渡到双宿主生命周期，其中包括猎物物种作为中间宿主。我们使用最优模型来探索这个想法，并讨论它与自由生活物种中已知的扩散策略，特别是动物扩散的关系。该模型发现，只有当中间宿主比最终宿主更丰富时，选择才会有利于复杂的生命周期。复杂生命周期的选择性价值随着最终宿主对中间宿主的捕食率而增加。在探索传播策略之间的权衡时，我们发现成本较高的权衡会使 CLC 的进化变得更加困难，而性状之间成本较低的权衡可能有利于混合策略。
Although multihost complex life cycles (CLCs) are common in several distantly related groups of parasites, their evolution remains poorly understood. In this article, we argue that under particular circumstances, adding a second host to a single-host life cycle is likely to enhance transmission (i.e., reaching the target host). For instance, in several situations, the propagules of a parasite exploiting a predator species will achieve a higher host-finding success by encysting in a prey of the target predator than by other dispersal modes. In such a case, selection should favor the transition from a single-to a two-host life cycle that includes the prey species as an intermediate host. We use an optimality model to explore this idea, and we discuss it in relation to dispersal strategies known among free-living species, especially animal dispersal. The model found that selection favored a complex life cycle only if intermediate hosts were more abundant than definitive hosts. The selective value of a complex life cycle increased with predation rates by definitive hosts on intermediate hosts. In exploring trade-offs between transmission strategies, we found that more costly trade-offs made it more difficult to evolve a CLC while less costly trade-offs between traits could favor a mixed strategy.