THERMAL TOLERANCE MISMATCH EXPLAINS PATTERNS OF PATHOGEN PREVALENCE
WITHIN AND AMONG FROG SPECIES
Abstract
Emerging infectious diseases threaten many wildlife populations, yet
there is considerable variation in pathogen impacts both within and
among species. Understanding this variability is key to identifying
where and when pathogens will have substantial effects. Here we use data
on prevalence of the invasive pathogen Batrachochytrium dendrobatidis
(Bd) in Australian frogs to test two predictions derived from the
hypothesis that mismatches in host-pathogen thermal tolerances can
explain prevalence patterns. We show that: 1) the slope of the
relationship between Bd prevalence and temperature within host species
transitions predictably from positive to increasingly negative as the
host species’ thermal optima increases; and 2) among host species, mean
Bd prevalence increases, peaks, and declines as the host species’
thermal optima increase. Both results align with theoretical
expectations and suggest that mismatches in environmental tolerance
between hosts and pathogens can explain much of the variation in
pathogen impacts observed within and among species.