Host species composition influences infection severity among amphibians in the absence of spillover transmission

Ecology and Evolution

Barbara A. Han³  Jacob L. Kerby¹  Catherine L. Searle²  Andrew Storfer⁴ 

[1] Biology Department, University of South Dakota, Vermillion, South Dakota;Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan;Cary Institute of Ecosystem Studies, New York;School of Biological Sciences, Washington State University, Pullman, Washington

关键词: Batrachochytrium;    biodiversity;    chytridiomycosis;    community structure;    dilution effect;    disease risk;    diversity‐disease;    tadpole;   

DOI  :  10.1002/ece3.1385

来源: Wiley

【 摘 要 】

Abstract

Wildlife epidemiological outcomes can depend strongly on the composition of an ecological community, particularly when multiple host species are affected by the same pathogen. However, the relationship between host species richness and disease risk can vary with community context and with the degree of spillover transmission that occurs among co-occurring host species. We examined the degree to which host species composition influences infection by Batrachochytrium dendrobatidis (Bd), a widespread fungal pathogen associated with amphibian population declines around the world, and whether transmission occurs from one highly susceptible host species to other co-occurring host species. By manipulating larval assemblages of three sympatric amphibian species in the laboratory, we characterized the relationship between host species richness and infection severity, whether infection mediates growth and survivorship differently across various combinations of host species, and whether Bd is transmitted from experimentally inoculated tadpoles to uninfected tadpoles. We found evidence of a dilution effect where Bd infection severity was dramatically reduced in the most susceptible of the three host species (Anaxyrus boreas). Infection also mediated survival and growth of all three host species such that the presence of multiple host species had both positive (e.g., infection reduction) and negative (e.g., mortality) effects on focal species. However, we found no evidence that Bd infection is transmitted by this species. While these results demonstrate that host species richness as well as species identity underpin infection dynamics in this system, dilution is not the product of reduced transmission via fewer infectious individuals of a susceptible host species. We discuss various mechanisms, including encounter reduction and antagonistic interactions such as competition and opportunistic cannibalism that may act in concert to mediate patterns of infection severity, growth, and mortality observed in multihost communities.

【 授权许可】

CC BY   
© 2015 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

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