Evolution of tolerance: the genetic basis of a host's resistance against parasite manipulation
Evolution of tolerance: the genetic basis of a host's resistance against parasite manipulation
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DOI：
10.1034/j.1600-0706.2003.12537.x
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发表时间：
2003-08-01
期刊：
影响因子：
3.4
通讯作者：
Koella, JC
中科院分区：
文献类型：
--
作者：
Hansen, MHH;Koella, JC
尽管在宿主-寄生虫系统的进化生物学方面取得了相当大的理论进展，但我们对自然系统中宿主-寄生虫协同进化的认识往往是有限的。实验见解落后于理论的原因之一是寄生虫的毒力不是一个简单的由寄生虫基因控制的特征。相反，由于宿主和寄生虫之间的微妙相互作用，毒力可以在几个性状中表达。此外，如果有足够的遗传变异来减少寄生虫对这些性状的不利影响，宿主可能会进化出对寄生虫的耐受性。我们研究了潜在的毒力和遗传潜力，以进化的宿主-寄生虫系统的埃及伊蚊-Brachiola algerae感染的耐受性的特点。我们以半同胞设计饲养蚊子，将每个全同胞家庭中的一半个体暴露于寄生虫，并测量了感染和未感染个体的几种生活史特征-青少年死亡率，化蛹年龄和成年大小。毒性在很大程度上是由于蚊子化蛹的年龄延迟了约10%。虽然这对蚊子施加了强大的选择压力来抵抗寄生虫，但所有的蚊子都被感染了，这意味着缺乏抵抗力。此外，虽然其他性状的加性遗传变异，我们没有发现任何迹象的加性遗传变异的年龄在化蛹，也没有延迟化蛹由于感染，这意味着没有潜力的耐受性的演变。总的来说，结果表明，在这种宿主-寄生虫系统中，宿主对寄生虫毒力的表达几乎没有进化控制。
Despite considerable theoretical advances in the evolutionary biology of host-parasite systems, our knowledge of host-parasite coevolution in natural systems is often limited. Among the reasons for the lag of experimental insight behind theory is that the parasite's virulence is not a simple trait that is controlled by the parasite's genes. Rather, virulence can be expressed in several traits due to the subtle interactions between the host and the parasite. Furthermore, the host might evolve tolerance to the parasite if there is sufficient genetic variance to reduce the detrimental effect of the parasite on these traits. We studied the traits underlying virulence and the genetic potential to evolve tolerance to infection in the host-parasite system Aedes aegypti-Brachiola algerae. We reared the mosquitoes in a half-sib design, exposed half of the individuals in each full-sib family to the parasite and measured several life history traits - juvenile mortality, age at pupation and adult size - of infected and uninfected individuals. Virulence was due in large part to a delay of the mosquito's age at pupation by about 10%. Although this imposes strong selection pressure on the mosquito to resist the parasite, all of the mosquitoes were infected, implying a lack of resistance. Furthermore, although additive genetic variance was present for other traits, we found no indication of additive genetic variation for the age at pupation, nor for the delay of pupation due to infection, implying no potential for the evolution of tolerance. Overall, the results suggest that in this host-parasite system, the host has little evolutionary control over the expression of the parasite's virulence.