Host-parasite and genotype-by-environment interactions: Temperature modifies potential for selection by a sterilizing pathogen
Host-parasite and genotype-by-environment interactions: Temperature modifies potential for selection by a sterilizing pathogen
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DOI：
10.1111/j.0014-3820.2005.tb00895.x
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发表时间：
2005-01-01
期刊：
影响因子：
3.3
通讯作者：
Read, AF
中科院分区：
文献类型：
--
作者：
Mitchell, SE;Rogers, ES;Read, AF
寄生虫介导的选择在调节遗传多样性方面具有潜在的重要性。抗性的遗传变异是自然选择的燃料，在宿主-寄生虫相互作用中似乎很常见，但很少观察到对选择的反应。在本研究中，我们测试了环境变化是否可以介导感染并决定进化结果。温度显着改变寄生虫介导的选择在两个独立的实验室感染实验在四个温度下的潜力。这种细菌寄生虫，雨状巴氏杆菌，在20摄氏度和25摄氏度时毒性极强，它的宿主大型蚤（Daphnia magna）会被杀死，所以雌性通常不会产生一个后代。然而，在10摄氏度和15摄氏度时，宿主-寄生虫的相互作用要良性得多，因为几乎所有的雌性都在不育之前产生了育雏。毒力和温度之间的这种关联可以稳定共存，并导致多样性的维持，因为它会削弱寄生虫介导的选择在部分季节。此外，高度显着的基因型与环境的相互作用被发现，在不同温度下的感染率的克隆排名顺序的变化。我们的研究结果清楚地表明，寄生虫介导的选择在这个系统中的结果是强烈的上下文依赖。
Parasite-mediated selection is potentially of great importance in modulating genetic diversity. Genetic variation for resistance, the fuel for natural selection, appears to be common in host-parasite interactions, but responses to selection are rarely observed. In the present study, we tested whether environmental variation could mediate infection and determine evolutionary outcomes. Temperature was shown to dramatically alter the potential for parasite-mediated selection in two independent laboratory infection experiments at four temperatures. The bacterial parasite, Pasteuria rainosa, was extremely virulent at 20degreesC and 25degreesC, sterilizing its host, Daphnia magna, so that females often never produced a single brood. However, at 10degreesC and 15degreesC, the host-parasite interaction was much more benign, as nearly all females produced broods before becoming sterile. This association between virulence and temperature alone could stabilize coexistence and lead to the maintenance of diversity, because it would weaken parasite-mediated selection during parts of the season. Additionally, highly significant genotype-by-environment interactions were found, with changes in clone rank order for infection rates at different temperatures. Our results clearly show that the outcome of parasite-mediated selection in this system is strongly context dependent.