Premium
Linking manipulative experiments to field data to test the dilution effect
Author(s) -
Venesky Matthew D.,
Liu Xuan,
Sauer Erin L.,
Rohr Jason R.
Publication year - 2014
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1111/1365-2656.12159
Subject(s) - biology , species richness , abundance (ecology) , ecology , obligate , relative species abundance , chytridiomycosis , dilution , zoology , amphibian , physics , thermodynamics
Summary The dilution effect, the hypothesis that biodiversity reduces disease risk, has received support in many systems. However, few dilution effect studies have linked mechanistic experiments to field patterns to establish both causality and ecological relevance. We conducted a series of laboratory experiments and tested the dilution effect hypothesis in an amphibian‐ B atrachochytrium dendrobatidis ( B d ) system and tested for consistency between our laboratory experiments and field patterns of amphibian species richness, host identity and B d prevalence. In our laboratory experiments, we show that tadpoles can filter feed B d zoospores and that the degree of suspension feeding was positively associated with their dilution potential. The obligate suspension feeder, G astrophryne carolinensis , generally diluted the risk of chytridiomycosis for tadpoles of B ufo terrestris and H yla cinerea , whereas tadpoles of B . terrestris (an obligate benthos feeder) generally amplified infections for the other species. In addition, G . carolinensis reduced B d abundance on H . cinerea more so in the presence than absence of B . terrestris and B . terrestris amplified B d abundance on H . cinerea more so in the absence than presence of G . carolinensis . Also, when ignoring species identity, species richness was a significant negative predictor of B d abundance. In our analysis of field data, the presence of B ufo spp. and G astrophryne spp. were significant positive and negative predictors of B d prevalence, respectively, even after controlling for climate, vegetation, anthropogenic factors (human footprint), species richness and sampling effort. These patterns of dilution and amplification supported our laboratory findings, demonstrating that the results are likely ecologically relevant. The results from our laboratory and field data support the dilution effect hypothesis and also suggest that dilution and amplification are predictable based on host traits. Our study is among the first to link manipulative experiments, in which a potential dilution mechanism is supported, with analyses of field data on species richness, host identity, spatial autocorrelation and disease prevalence.