Fungal Panzootic Increasingly Threatens Temperate Amphibian Species While Impact Has Stabilised in Equatorial Regions

Global amphibian declines outpace the loss of most organisms on Earth. The panzootic fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is widely regarded as a predominant driver behind amphibian biodiversity erosion. However, a comprehensive global-scale analysis of the relationship between Bd and extinction risk remains lacking. Using a global database of Bd-detections and IUCN Red List extinction risk, we show that current amphibian declines are associated with Bd in temperate regions only, whereas historical analyses reveal a past peak of Bd-related declines across more equatorial areas during 1980-2004, that has diminished in intensity in recent decades (2004-2020). In contrast, temperate species show a lack of Bd-related declines during 1980-2004 but significant declines are currently ongoing. We suggest that the shorter activity seasons in temperate regions may have acted as 'natural lockdowns' that delayed the annihilating effects of Bd in susceptible species. Conversely, year-round activity in more amphibian-dense, equatorial areas may have triggered a faster transition into post-epizootic dynamics, characterised by a continuous high-intensity outbreak followed by amphibian population stabilisation and pathogen persistence at lower levels.