Batrachochytrium salamandrivorans thermal phenotypic variation

Recognizing the influence of pathogen diversity on infection dynamics is
crucial for mitigating emerging infectious diseases. Characterising such
diversity is often complex, for instance when multiple pathogen variants
exist that interact differently with the environment and host. Here, we
explore genotypic and phenotypic variation of Batrachochytrium
salamandrivorans (Bsal), an emerging fungal pathogen that is driving
declines among an increasing number of European amphibian species. For
thirteen isolates, spanning most of the known temporal and geographical
Bsal range in Europe, we mapped phenotypic diversity through numerous
measurements that describe varying reproductive rates in vitro across a
range of temperatures. Bsal isolates are revealed to have different
thermal optima and tolerances, with phenotypic variation correlating with
genomic diversity. Using a mechanistic niche model of the fire salamander
(Salamandra salamandra) as an example, we illustrate how host steady-state
body temperature and Bsal thermal range variation may influence pathogen
growth through space and time across Europe. Our combined findings show
how the identity of emergent pathogen variants may strongly influence when
and which host populations are most at risk.