Quantifying the population-level cost of amphibian chytridiomycosis in a changing montane ecosystem

Background The emerging panzootic of amphibian chytridiomycosis has had profound deleterious effects on communities and ecosystems in many areas of the world. Our research has shown that Batrachochytrium dendrobatidis (Bd) is being widely introduced across Europe. However, we do not yet have the data to ascertain the effects of these introductions on the diversity and dynamics of naïve, and native, amphibian species and communities across short, and medium-length, timescales. Study System This study will make use of an Iberian dataset that we have been collecting since 2003. We have surveyed midwive toads (Alytes obstetricans) in 126 sites, and have identified 31 where infection occurs. Most notably, this survey has shown that Bd has been introduced into a small region of the western Pyrenees. Within this region, we have been tracking infection in detail since 2007 by collecting prevalence, pathogen genotypes, and mortality data. The student will be able to use this dataset to evaluate hypotheses about the relative roles of biotic and abiotic drivers in modulating the host-pathogen dynamic between asymptomatic and symptomatic infection. By building upon our previous work, the student will have the opportunity to match infected and uninfected lakes that span a wide range of altitude. At the same time, they will have access to fine-grain meteorological variables as well as mortality data for infected lakes. This will allow the student to measure the amount of mortality that is attributable to Bd-infection across spatial and temporal scales. Analysis of the covariates (biotic and abiotic) will be used to model the relative viability of infected versus uninfected populations, and our understanding of how climate-change will effect these mountains will be used to develop future predictions. The project partner (ZSL) has a history of working on Bd that goes back to the original discovery of the pathogen, and whom have a global-outreach program in mitigating the effects of chytridiomycosis. The collaborators (CNRS) have a key role in studying the emergence of Bd in the Pyrenees and are key partners in RACE (Risk Assessment of Chytridiomycosis to European amphibian biodiversity). This project builds upon a strong working relationship between TWJG and MCF that has yielded 15 publications and a current co-held NERC grant. They also co-supervise a NERC student on the genetics and virulence of Bd, whose findings will be integrated into this PhD project.