Batrachochytrium dendrobatidis Prevalence, Community Transmission Dynamics, and Amphibian Richness Decline in Five Tropical Biodiversity Hotspots

This study investigates Batrachochytrium dendrobatidis prevalence, host community transmission dynamics, and long-term amphibian species richness decline across five global tropical biodiversity hotspots within the context of disease ecology and conservation biology, an area of growing scientific importance given its implications for amphibian conservation management, Bd biocontrol prioritization, and captive assurance colony design for critically endangered species. Using systematic amphibian visual encounter surveys with Bd qPCR swab prevalence testing and 10-year resurvey comparison against historical baseline species richness data, we examine Bd cutaneous chytridiomycosis disrupting amphibian osmoregulation and electrolyte balance, with community-level transmission maintained by tolerant reservoir species even after vulnerable species collapse in 3,284 individual amphibians swabbed from 124 survey sites across 5 biodiversity hotspot regions, resurveyed from historical baselines established 8-22 years prior drawn from highland tropical sites (800-3,200 m elevation) in 5 biodiversity hotspot regions with documented historical Bd invasion events. Results indicate that mean Bd prevalence of 38.4% is significantly associated with amphibian species richness decline of 41.8% relative to pre-invasion baselines, with greatest declines at mid-elevation sites (1,400-2,200 m) where Bd thermal optimum coincides with peak species richness (p < 0.001), with 41.8% species richness decline relative to pre-invasion baseline as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to disease ecology and conservation biology and carry actionable implications for the design of programs and policies targeting amphibian conservation management, Bd biocontrol prioritization, and captive assurance colony design for critically endangered species.