THE EVOLUTION OF VIRULENCE IN PARASITES AND PATHOGENS - RECONCILIATION BETWEEN 2 COMPETING HYPOTHESES
THE EVOLUTION OF VIRULENCE IN PARASITES AND PATHOGENS - RECONCILIATION BETWEEN 2 COMPETING HYPOTHESES
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DOI：
10.1006/jtbi.1994.1146
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发表时间：
1994-08-07
影响因子：
2
通讯作者：
MAY, RM
中科院分区：
文献类型：
--
作者：
LENSKI, RE;MAY, RM
根据传统观点，寄生虫和病原体应该进化出对宿主的毒性降低，因为毒性更强的寄生虫和病原体更有可能使宿主和它们自己灭绝。但这一观点因其依赖群体选择而受到批评。根据另一种观点，选择将有利于使寄生虫或病原体的增长率最大化的任何毒力水平。这种最佳毒力取决于寄生虫或病原体的传播性及其对宿主死亡率的影响之间的功能关系，选择往往有利于中等程度的毒力。本文的论点是，模型中，中间水平的毒力是有利的，很自然地导致进一步的结论，寄生虫和病原体应该在一定程度上成为毒性随着时间的推移，一旦生态和进化过程之间的反馈纳入分析。由于寄生虫或病原体的连续适应，易感宿主的密度降低，从而改变了选择力之间的平衡，从而有利于降低毒力。然而，所实现的进化稳定策略与完全无毒是有界限的。我们的结论是，从长远来看，中等毒力的模型并不一定与传统观点相矛盾;事实上，这些模型为毒力降低的进化提供了一个简单的机制解释。
According to conventional wisdom, parasites and pathogens should evolve reduced virulence to their hosts, because more virulent parasites and pathogens are more likely to drive their hosts, and themselves, to extinction. But this view has been criticized for its reliance on group selection. According to an alternative perspective, selection will favor whatever level of virulence maximizes the rate of increase of the parasite or pathogen. This optimum virulence depends on the functional relationship between a parasite or pathogen's transmissibility and its effect on host mortality, with selection often favoring an intermediate degree of virulence. The thesis of this paper is that models in which intermediate levels of virulence are favored lead quite naturally to the further conclusion that parasites and pathogens should-up to a point-become less virulent over time, once the feedbacks between ecological and evolutionary processes are incorporated into the analysis. As a consequence of successive adaptations by the parasite or pathogen, the density of susceptible hosts is reduced, thereby altering the balance between selective forces so as to favor reduced virulence. However, the evolutionarily stable strategy that is achieved is bounded away from complete avirulence. We conclude that models in which intermediate virulence is favored do not necessarily contradict the conventional wisdom in the long run; in fact, these models provide a simple mechanistic explanation for the evolution of reduced virulence.