1 Ecology and Evolutionary Biology, University of Colorado , Boulder, CO , USA.
2 Department of Chemistry and Biology, Ryerson University , Toronto, Ontario , Canada.
Proc Biol Sci. 2019 May 15;286(1902):20190260. doi: 10.1098/rspb.2019.0260.
Debates over the relationship between biodiversity and disease dynamics underscore the need for a more mechanistic understanding of how changes in host community composition influence parasite transmission. Focusing on interactions between larval amphibians and trematode parasites, we experimentally contrasted the effects of host richness and species composition to identify the individual and joint contributions of both parameters on the infection levels of three trematode species. By combining experimental approaches with field surveys from 147 ponds, we further evaluated how richness effects differed between randomized and realistic patterns of species loss (i.e. community disassembly). Our results indicated that community-level changes in infection levels were owing to host species composition, rather than richness. However, when composition patterns mirrored empirical observations along a natural assembly gradient, each added host species reduced infection success by 12-55%. No such effects occurred when assemblages were randomized. Mechanistically, these patterns were due to non-random host species assembly/disassembly: while highly competent species predominated in low diversity systems, less susceptible hosts became progressively more common as richness increased. These findings highlight the potential for combining information on host traits and assembly patterns to forecast diversity-mediated changes in multi-host disease systems.
关于生物多样性与疾病动态之间关系的争论，凸显了我们需要更深入地了解宿主群落组成变化如何影响寄生虫传播，这需要一种更具机械性的理解。本研究以幼体两栖动物和吸虫寄生虫之间的相互作用为重点，通过对比实验，研究了宿主丰富度和物种组成的影响，以确定这两个参数对三种吸虫物种感染水平的单独和联合贡献。通过将实验方法与来自 147 个池塘的实地调查相结合，我们进一步评估了丰富度效应在随机和现实物种丧失模式（即群落解体）之间的差异。结果表明，感染水平的群落级变化是由宿主物种组成引起的，而不是丰富度。然而，当组成模式反映了沿着自然组装梯度的经验观察时，每个增加的宿主物种将感染成功率降低了 12-55%。当组合随机化时，不会发生这种影响。从机制上讲，这些模式是由于宿主物种组装/解体的非随机性：虽然高能力物种在低多样性系统中占主导地位，但随着丰富度的增加，较少易感染的宿主逐渐变得更为常见。这些发现强调了结合宿主特征和组装模式信息来预测多宿主疾病系统中多样性介导的变化的潜力。
