Archival mitogenomes identify invasion by the CAPE lineage caused an African amphibian extinction in the wild.

Outbreaks of emerging infectious diseases are influenced by local biotic and abiotic factors, with host declines occurring when conditions favour the pathogen. Deterioration in the population of the micro-endemic Tanzanian Kihansi spray toad () occurred after the construction of a hydropower dam, implicating habitat modification in this species decline. Population recovery followed habitat augmentation; however, a subsequent outbreak of chytridiomycosis caused by () led to the spray toad's extinction in the wild. We show using spatiotemporal surveillance and mitogenome assembly of from archived toad mortalities that the outbreak was caused by invasion of the CAPE lineage and not the panzootic lineage GPL. Molecular dating reveals an emergence of CAPE across southern Africa overlapping with the timing of the spray toad's extinction. That our post-outbreak surveillance of co-occurring amphibian species in the Udzungwa Mountains shows widespread infection by CAPE yet no signs of ill-health or decline suggests these other species can tolerate when environments are stable. We conclude that, despite transient success in mitigating the impact caused by dams' construction, invasion by CAPE caused the ultimate die-off that led to the extinction of the Kihansi spray toad.