生物多样性与传染病风险

近半个世纪以来,新发传染病(多为涉及多宿主的人兽共患病)正在以前所未有的速度不断增加,不仅严重威胁人类健康,还影响着农业生产和野生动物保护。因不同宿主对病原的传播能力具有种间差异,宿主群落结构能够显著地影响病原的传播动态和传染病风险。多样性,作为表征群落结构的重要指标之一,其和传染病风险间的关系(即多样性-疾病关系)是传染病生态学研究的核心问题之一。尤其是“稀释效应”(即提高宿主多样性能够降低疾病风险)的提出引发了广泛的关注。虽然稀释效应得到了众多实证研究的支持,但其普适性仍然存在争议。笔者围绕多样性-疾病关系,介绍稀释效应的生态学机制、普适性及其产生的前提条件。并就3个方向总结了稀释效应的研究进展:①稀释效应的尺度依赖性;②宿主局部灭绝风险和其病原传播能力间的关系;③多样性对疾病风险的身份效应。此外,还分析了近期关于多样性-疾病关系研究框架的拓展,即从物种多样性拓展到谱系多样性;从单一疾病风险拓展到疾病总负担。最后,就未来可能的研究方向提出展望,认为未来研究需探讨分析生境破碎化、非宿主以及群落功能多样性在多样性-疾病关系中的作用。

Biodiversity and the risk of infectious diseases

Emerging infectious diseases, most of which are zoonoses involving multiple host species, have been increasing at an unprecedented rate during the last 50 years. These diseases impact both public health, animal husbandry, and wildlife conservation. Generally, species vary considerably in their competence for transmitting pathogens, thus the host community composition can potentially influence the pathogen transmission dynamics and disease risk. The relationships between host diversity, as the most important index for host community composition, and disease risk (i.e. the diversity-disease relationships) is an important topic in disease ecology. Particularly, the dilution effect (i.e. increased host diversity can reduce disease risk) has attracted wide attention. While the dilution effect hypothesis has been supported by many empirical studies, its generality is still under active debates. In this article, we introduce the mechanisms underlying the dilution effect, and the prerequisites for its generality. We then reviewed the research progress on the diversity-disease relationship in three directions: ① the scale-dependence of the dilution effect; ② the relationship between species’ reservoir competence and local extinction risk; and ③ the identity effect of host diversity. In addition, we also summarized the current extension of the diversity-disease relationships: from species diversity to phylogenetic diversity, and from the risk of single disease to the disease burden. Finally, we consider that the future studies should try to explore the effects of habitat fragmentation, non-host, and community functional diversity on the diversity-disease relationships.