Biological & Environmental Sciences, University of Stirling, Stirling, UK.
Biological & Environmental Sciences & Gothenburg Global Biodiversity Centre, University of Gothenburg, Gothenburg, Sweden.
Proc Biol Sci. 2023 Mar 29;290(1995):20222139. doi: 10.1098/rspb.2022.2139. Epub 2023 Mar 22.
Epidemics commonly exert parasite-mediated selection and cause declines in host population genetic diversity. This can lead to evolution of resistance in the long term and smaller subsequent epidemics. Alternatively, the loss of genetic diversity can increase host vulnerability to future disease spread and larger future epidemics. Matters are made more complex by the fact that a great many host organisms produce diapausing life stages in response to environmental change (often as a result of sexual reproduction; e.g. plant seeds and invertebrate resting eggs). These diapausing stages can disrupt the relationship between past epidemics, host genetic diversity and future epidemics because they allow host dispersal through time. Specifically, temporally dispersing hosts avoid infection and thus selection from contemporary parasites, and also archive genetic variation for the future. We studied 80 epidemics in 20 semi-natural populations of the temporally dispersing crustacean and its sterilizing bacterial parasite , and half of these populations experienced a simulated environmental disturbance treatment. We found that early initiation of diapause relative to the timing of the epidemic led to greater host genetic diversity and reduced epidemic size in the subsequent year, but this was unaffected by environmental disturbance.
传染病通常会通过寄生虫介导的选择作用，导致宿主种群遗传多样性减少。从长远来看，这可能导致宿主对寄生虫产生抗性，从而降低后续传染病的规模。或者，遗传多样性的丧失可能会增加宿主对未来疾病传播和更大规模未来传染病的脆弱性。更为复杂的是，大量宿主生物会产生滞育生命阶段，以应对环境变化（通常是由于有性繁殖；例如植物种子和无脊椎动物休眠卵）。这些滞育阶段会破坏过去传染病、宿主遗传多样性和未来传染病之间的关系，因为它们允许宿主在时间上扩散。具体来说，随着时间的推移而分散的宿主可以避免感染和当前寄生虫的选择，同时也为未来存储遗传变异。我们研究了 80 个传染病在 20 个半自然种群的时间分散甲壳动物及其绝育细菌寄生虫，并对其中一半种群进行了模拟环境干扰处理。我们发现，与传染病发生时间相比，早期开始滞育会导致随后一年宿主遗传多样性增加，传染病规模减小，但这不受环境干扰的影响。
