Buss Nicholas, Hua Jessica
Department of Biological Sciences, Binghamton University (SUNY), Binghamton, New York, USA.
Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
J Anim Ecol. 2023 Nov;92(11):2151-2162. doi: 10.1111/1365-2656.13988. Epub 2023 Aug 16.
Hosts and parasites are embedded in communities where species richness and composition can influence disease outcomes (diversity-disease relationships). The direction and magnitude of diversity-disease relationships are influenced by variation in competence (ability to support and transmit infections) of hosts in a community. However, host susceptibility to parasites, which mediates host competence, is not static and is influenced by environmental factors, including pollutants. Despite the role that pollutants can play in augmenting host susceptibility, how pollutants influence diversity-disease dynamics is not well understood. Using an amphibian-trematode model, we tested how NaCl influences diversity-disease dynamics. We predicted that NaCl exposure can alter relative susceptibility of host species to trematodes, leading to cascading effects on the diversity-disease relationship. To test these predictions, we exposed hosts to benign or NaCl environments and generated communities that differed in number and composition of host species. We exposed these communities to trematodes and measured disease outcomes at the community (total infections across all hosts within a community) and species levels (average number of infections per host species within a community). Host species differed in their relative susceptibility to trematodes when exposed to NaCl. Consequently, at the community level (total infections across all hosts within a community), we only detected diversity-disease relationships (dilution effects) in communities where hosts were exposed to NaCl. At the species level, disease outcomes (average number of infections/species) and whether multi-species communities supported lower number of infections relative to single-species communities depended on community composition. Notably, however, as with overall community infection, diversity-disease relationships only emerged when hosts were exposed to NaCl. Synthesis. Pollutants are ubiquitous in nature and can influence disease dynamics across a number of host-parasite systems. Here, we show that NaCl exposure can alter the relative susceptibility of host species to parasites, influencing the relationship between biodiversity and disease at both community and species levels. Collectively, our study contributes to the limited knowledge surrounding environmental mediators of host susceptibility and their influence on diversity-disease dynamics.
宿主和寄生虫存在于物种丰富度和组成会影响疾病结果（多样性 - 疾病关系）的群落之中。多样性 - 疾病关系的方向和强度受群落中宿主的易感性（支持和传播感染的能力）变化影响。然而，介导宿主易感性的宿主对寄生虫的易感性并非一成不变，且受包括污染物在内的环境因素影响。尽管污染物在增强宿主易感性方面可能发挥作用，但污染物如何影响多样性 - 疾病动态仍未得到充分理解。我们使用两栖动物 - 吸虫模型，测试了氯化钠如何影响多样性 - 疾病动态。我们预测，暴露于氯化钠环境会改变宿主物种对吸虫的相对易感性，从而对多样性 - 疾病关系产生连锁反应。为了验证这些预测，我们将宿主暴露于良性或含氯化钠的环境中，并构建了宿主物种数量和组成不同的群落。我们将这些群落暴露于吸虫中，并在群落水平（群落内所有宿主的总感染数）和物种水平（群落内每个宿主物种的平均感染数）测量疾病结果。暴露于氯化钠环境时，宿主物种对吸虫的相对易感性存在差异。因此，在群落水平（群落内所有宿主的总感染数），我们仅在宿主暴露于氯化钠的群落中检测到多样性 - 疾病关系（稀释效应）。在物种水平，疾病结果（每个物种的平均感染数）以及多物种群落相对于单物种群落是否支持更低的感染数取决于群落组成。然而，值得注意的是，与总体群落感染情况一样，多样性 - 疾病关系仅在宿主暴露于氯化钠时才出现。总结。污染物在自然界中无处不在，可影响多个宿主 - 寄生虫系统中的疾病动态。在此，我们表明，暴露于氯化钠环境会改变宿主物种对寄生虫的相对易感性，影响群落和物种水平上生物多样性与疾病之间的关系。总体而言，我们的研究为关于宿主易感性的环境调节因子及其对多样性 - 疾病动态的影响这一有限的知识体系做出了贡献。
