Data from: Genetic erosion in wild populations makes resistance to a pathogen more costly

Populations that have suffered from genetic erosion are expected to exhibit reduced average trait values or decreased variation in adaptive traits when experiencing periodic or emergent stressors such as infectious disease. Genetic erosion may consequentially modify the ability of a potential host population to cope with infectious disease emergence. We experimentally investigate this relationship between genetic variability and host response to exposure to an infectious agent both in terms of susceptibility to infection and indirect parasite-mediated responses that also impact fitness. We hypothesized that the deleterious consequences of exposure to the pathogen (Batrachochytrium dendrobatidis) would be more severe for tadpoles descended from European tree frog (Hyla arborea) populations lacking genetic variability. Although all exposed tadpoles lacked detectable infection, we detected this relationship for some indirect host responses, predominantly in genetically depleted animals, as well as an interaction between genetic variability and pathogen dose on lifespan during the post-metamorphic period. Lack of infection and a decreased mass and post-metamorphic lifespan in low genetic diversity tadpoles lead us to conclude that genetic erosion, while not affecting the ability to mount effective resistance strategies, also erodes the capacity to invest in resistance, increased tadpole growth rate and metamorphosis relatively simultaneously.

曾经历遗传侵蚀（genetic erosion）的种群，在面临周期性或突发性应激源（如传染性疾病）时，其平均性状值往往会降低，适应性性状的变异程度也会下降。遗传侵蚀可能会进而改变宿主种群应对传染性疾病暴发的能力。我们通过实验探究了遗传变异性与宿主对病原体暴露的响应之间的关联，该响应同时涵盖感染易感性以及同样影响适合度（fitness）的寄生虫间接介导响应。我们提出假说：暴露于蛙壶菌（Batrachochytrium dendrobatidis）所产生的有害后果，在遗传变异性匮乏的欧洲树蛙（Hyla arborea）种群的蝌蚪中会更为显著。尽管所有接受病原体暴露的蝌蚪均未检测到感染，但我们在部分间接宿主响应中观测到了前述关联，且该关联主要出现在遗传耗竭的个体中；同时还发现遗传变异性与病原体剂量在蝌蚪变态后的寿命上存在交互作用。低遗传多样性蝌蚪既未出现感染，同时体重与变态后寿命均有所降低，据此我们得出结论：遗传侵蚀虽未影响宿主启动有效抗性策略的能力，但会相对同步地削弱其投入抗性反应、提升蝌蚪生长速率与推进变态进程的能力。