Odum School of Ecology, College of Veterinary Medicine; University of Georgia, Athens, GA, USA.
Center for the Ecology of Infectious Diseases, College of Veterinary Medicine; University of Georgia, Athens, GA, USA.
Biol Lett. 2020 Nov;16(11):20200559. doi: 10.1098/rsbl.2020.0559. Epub 2020 Nov 18.
Anthropogenic landscape modification such as urbanization can expose wildlife to toxicants, with profound behavioural and health effects. Toxicant exposure can alter the local transmission of wildlife diseases by reducing survival or altering immune defence. However, predicting the impacts of pathogens on wildlife across their ranges is complicated by heterogeneity in toxicant exposure across the landscape, especially if toxicants alter wildlife movement from toxicant-contaminated to uncontaminated habitats. We developed a mechanistic model to explore how toxicant effects on host health and movement propensity influence range-wide pathogen transmission, and zoonotic exposure risk, as an increasing fraction of the landscape is toxicant-contaminated. When toxicant-contaminated habitat is scarce on the landscape, costs to movement and survival from toxicant exposure can trap infected animals in contaminated habitat and reduce landscape-level transmission. Increasing the proportion of contaminated habitat causes host population declines from combined effects of toxicants and infection. The onset of host declines precedes an increase in the density of infected hosts in contaminated habitat and thus may serve as an early warning of increasing potential for zoonotic spillover in urbanizing landscapes. These results highlight how sublethal effects of toxicants can determine pathogen impacts on wildlife populations that may not manifest until landscape contamination is widespread.
人为的景观改造，如城市化，会使野生动物暴露在有毒物质中，从而对其行为和健康产生深远影响。有毒物质的暴露会通过降低生存能力或改变免疫防御来改变野生动物疾病的本地传播。然而，由于景观中有毒物质暴露的异质性，预测病原体对野生动物的影响在其范围内变得复杂，特别是如果有毒物质改变了野生动物从受污染到未受污染栖息地的运动。我们开发了一种机制模型，以探讨宿主健康和运动倾向的有毒物质效应如何影响疾病的传播范围以及人畜共患病的暴露风险，因为景观中有毒物质污染的比例在不断增加。当景观中受污染的栖息地稀缺时，有毒物质暴露对运动和生存的成本会将受感染的动物困在污染的栖息地中，并减少景观水平的传播。受污染栖息地比例的增加会导致宿主种群因有毒物质和感染的综合影响而下降。宿主下降的开始先于受污染栖息地中受感染宿主密度的增加，因此可能成为城市化景观中人畜共患病溢出潜在增加的早期预警。这些结果强调了有毒物质的亚致死效应如何决定病原体对野生动物种群的影响，这些影响可能要到景观污染广泛存在时才会显现。
