PDF(Pubmed)
Abstract：
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 (Nectophrynoides asperginis) 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 Batrachochytrium dendrobatidis (Bd) led to the spray toad\'s extinction in the wild. We show using spatiotemporal surveillance and mitogenome assembly of Bd from archived toad mortalities that the outbreak was caused by invasion of the BdCAPE lineage and not the panzootic lineage BdGPL. Molecular dating reveals an emergence of BdCAPE 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 BdCAPE yet no signs of ill-health or decline suggests these other species can tolerate Bd when environments are stable. We conclude that, despite transient success in mitigating the impact caused by dams\' construction, invasion by BdCAPE caused the ultimate die-off that led to the extinction of the Kihansi spray toad.
摘要：
新发传染病的爆发受当地生物和非生物因素的影响，当条件有利于病原体时，宿主会下降。在建造水电大坝后，微特有的坦桑尼亚Kihansi喷雾蟾蜍（Nectophrynoidesasperginis）的种群恶化，暗示该物种的栖息地改变正在减少。随着栖息地的增加，人口恢复；然而，随后由Batrachochytriumdendrobatidis（Bd）引起的乳糜菌病的爆发导致了喷雾蟾蜍在野外的灭绝。我们从已存档的蟾蜍死亡率中使用Bd的时空监测和有丝分裂基因组组装表明，爆发是由BdCAPE谱系而不是全动物谱系BdGPL的入侵引起的。分子测年揭示了整个南部非洲BdCAPE的出现，与喷雾蟾蜍灭绝的时间重叠。我们对Udzungwa山脉同时发生的两栖动物物种的爆发后监测显示，BdCAPE广泛感染，但没有健康不良或下降的迹象表明，当环境稳定时，这些其他物种可以忍受Bd。我们的结论是，尽管在减轻大坝建设造成的影响方面取得了短暂的成功，BdCAPE的入侵导致了最终的死亡，导致了Kihansi喷雾蟾蜍的灭绝。
