Amphibian chytrid fungus in Africa – realigning hypotheses and the research paradigm

Abstract

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), responsible for numerous amphibian declines and extinctions, was previously thought to originate from the African continent. This was based on infected museum specimens from early 20th century South Africa, Cameroon and Uganda. Further research on archived specimens from other continents eventually revealed early 20th century records also in Brazil and Japan. Recent robust analysis of genomic diversity and phylogeny of Bd has shown origin from Asia to be more plausible. This raises the issue that the threat of Bd for African amphibians as a novel pathogen has been underestimated. There are now cases where dramatic amphibian declines in disparate mountains on the continent could be attributed to Bd, and this necessitates an urgent realigning of hypotheses and the research agenda for amphibian conservation on the continent. Notably, hotspots of amphibian host naivety include West Africa where this pathogen has so far not been detected. We discuss research gaps that amphibian conservationists might focus on, notably more genomic sequencing of the BdCAPE (the less virulent) lineage to determine its date of emergence, and assessing the susceptibility of different amphibian species to infection, disease and decline to better prioritize conservation actions