Integrative Biology, Oregon State University, Corvallis, Oregon, USA.
Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
Ecology. 2023 Feb;104(2):e3885. doi: 10.1002/ecy.3885. Epub 2022 Dec 1.
Losses in biodiversity can alter disease risk through changes in host species composition. Host species vary in pathogen susceptibility and competence, yet how changes in diversity alter host-pathogen dynamics remains unclear in many systems, particularly with respect to generalist pathogens. Amphibians are experiencing worldwide population declines linked to generalist pathogens, such as ranavirus, and thus represent an ideal group to investigate how host species composition affects disease risk. We conducted experiments in which amphibian larvae of three native species (Pacific tree frogs, Pseudacris regilla; Cascades frogs, Rana cascadae; and Western toads, Anaxyrus boreas) were exposed to ranavirus individually (in the laboratory) or as assemblages (in outdoor mesocosms). In a laboratory experiment, we observed low survival and high viral loads in P. regilla compared to the other species, suggesting that this species was highly susceptible to the pathogen. In the mesocosm experiment, we observed 41% A. boreas mortality when alone and 98% mortality when maintained with P. regilla and R. cascadae. Our results suggest that the presence of highly susceptible species can alter disease dynamics across multiple species, potentially increasing infection risk and mortality in co-occurring species.
生物多样性的丧失会通过宿主物种组成的变化改变疾病风险。宿主物种在病原体易感性和易感性方面存在差异，但在许多系统中，特别是在针对广义病原体的情况下，多样性变化如何改变宿主-病原体动态仍不清楚。两栖动物正经历着与广义病原体（如蛙病毒）相关的全球种群减少，因此是研究宿主物种组成如何影响疾病风险的理想群体。我们进行了实验，其中三种本地物种（太平洋树蛙、Pseudacris regilla；喀斯喀特蛙、Rana cascadae；西部蟾蜍、Anaxyrus boreas）的两栖动物幼虫单独（在实验室）或作为组合（在户外中观生态系统）暴露于蛙病毒中。在实验室实验中，与其他物种相比，我们观察到 P. regilla 的存活率低且病毒载量高，这表明该物种对病原体高度敏感。在中观生态系统实验中，当单独饲养 A. boreas 时，其死亡率为 41%，当与 P. regilla 和 R. cascadae 一起饲养时，其死亡率为 98%。我们的研究结果表明，高度易感物种的存在可能会改变多种物种的疾病动态，从而增加共存物种的感染风险和死亡率。
