Biological & Environmental Sciences, University of Stirling, Stirling, UK.
Glob Chang Biol. 2017 Dec;23(12):5045-5053. doi: 10.1111/gcb.13769. Epub 2017 Jul 8.
Climate change is causing warmer and more variable temperatures as well as physical flux in natural populations, which will affect the ecology and evolution of infectious disease epidemics. Using replicate seminatural populations of a coevolving freshwater invertebrate-parasite system (host: Daphnia magna, parasite: Pasteuria ramosa), we quantified the effects of ambient temperature and population mixing (physical flux within populations) on epidemic size and population health. Each population was seeded with an identical suite of host genotypes and dose of parasite transmission spores. Biologically reasonable increases in environmental temperature caused larger epidemics, and population mixing reduced overall epidemic size. Mixing also had a detrimental effect on host populations independent of disease. Epidemics drove parasite-mediated selection, leading to a loss of host genetic diversity, and mixed populations experienced greater evolution due to genetic drift over the season. These findings further our understanding of how diversity loss will reduce the host populations' capacity to respond to changes in selection, therefore stymying adaptation to further environmental change.
气候变化导致自然种群的温度升高和更加多变，以及物理通量发生变化，这将影响传染病流行的生态和进化。我们使用共进化的淡水无脊椎动物-寄生虫系统（宿主：大型溞，寄生虫：拉姆西亚斯）的重复半自然种群，量化了环境温度和种群混合（种群内的物理通量）对流行规模和种群健康的影响。每个种群都接种了相同的宿主基因型和寄生虫传播孢子剂量。环境温度的合理升高导致了更大的流行规模，而种群混合则降低了总体流行规模。混合对宿主种群也有不利影响，而与疾病无关。流行规模驱动了寄生虫介导的选择，导致宿主遗传多样性丧失，并且由于季节期间的遗传漂变，混合种群经历了更大的进化。这些发现进一步加深了我们对多样性丧失如何降低宿主种群应对选择变化的能力的理解，从而阻碍了对进一步环境变化的适应。
