Supplementary Figures from Stress hormones predict a host superspreader phenotype in the West Nile virus system

Supplementary Figure

Supplementary Results from Stress hormones predict a host superspreader phenotype in the West Nile virus system

Supplementary Results Table

Supplementary Methods from Stress hormones predict a host superspreader phenotype in the West Nile virus system

Supplementary Methods Section

gray tree frog_survival during Bd challenge

gray tree frog_survival during Bd challeng

wood frog_time to metamorphosis

wood frog_time to metamorphosi

survival from initiation of experiment to metamorphosis

survival from initiation of experiment to metamorphosi

wood frog_survival during Bd challenge

wood frog_survival during Bd challeng

Linking Ecology and Epidemiology to Understand Predictors of Multi-Host Responses to an Emerging Pathogen, the Amphibian Chytrid Fungus

<div><p>Variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. The fungal pathogen, <i>Batrachochytrium dendrobatidis</i> (Bd) has been detected in almost 700 different amphibian species and is implicated in numerous global amphibian population declines. Identifying key hosts in the amphibian-Bd system–those who are at greatest risk or who pose the greatest risk for others–is challenging due in part to many extrinsic environmental factors driving spatiotemporal Bd distribution and context-dependent host responses to Bd in the wild. One way to improve predictive risk models and generate testable mechanistic hypotheses about vulnerability is to complement what we know about the spatial epidemiology of Bd with data collected through comparative experimental studies. We used standardized pathogen challenges to quantify amphibian survival and infection trajectories across 20 post-metamorphic North American species raised from eggs. We then incorporated trait-based models to investigate the predictive power of phylogenetic history, habitat use, and ecological and life history traits in explaining responses to Bd. True frogs (<i>Ranidae</i>) displayed the lowest infection intensities, whereas toads (<i>Bufonidae</i>) generally displayed the greatest levels of mortality after Bd exposure. Affiliation with ephemeral aquatic habitat and breadth of habitat use were strong predictors of vulnerability to and intensity of infection and several other traits including body size, lifespan, age at sexual maturity, and geographic range also appeared in top models explaining host responses to Bd. Several of the species examined are highly understudied with respect to Bd such that this study represents the first experimental susceptibility data. Combining insights gained from experimental studies with observations of landscape-level disease prevalence may help explain current and predict future pathogen dynamics in the Bd system.</p></div

Phylogenetic reconstructions for response variables.

<p>(<b>A</b>) average infection load displayed as the natural logarithm of average <i>Batrachochytrium dendrobatidis</i> genome equivalents detected in amphibian skin after exposure to the pathogen, (<b>B</b>) log response ratio, displayed as the effect size for the difference in survival between the Bd and Control treatments, and (<b>C</b>) hazard ratio, describing the risk of mortality in the Bd treatment compared to the control treatment.</p

Phylogenetic signal as measured by Blomberg's K and associated significance values and transformations performed on response and explanatory variables to meet assumptions of linearity in predictive models.

<p>Two phylogenetic trees were used to quantify phylogenetic distance among species. K (Speciational) was based on previous studies of anuran phylogeny and assumed a speciational model of trait evolution. The other tree, K (Gradual) was estimated via maximum likelihood from 2500 bp of mitochondrial sequence data obtained from GenBank.</p