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Disease driven extinction in the wild of the Kihansi spray toad, Nectophrynoides asperginis
African Journal of Herpetology ( IF 1.5 ) Pub Date : 2020-04-24 , DOI: 10.1080/21564574.2020.1752313
Ché Weldon 1 , Alan Channing 1 , Gerald Misinzo 2 , Andrew A Cunningham 3
Affiliation  

ABSTRACT The Kihansi spray toad, Nectophrynoides asperginis, became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Previous investigations have indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the species extirpation. Here, we systematically investigate the role of disease in the extinction event of the wild toad population. The amphibian chytrid fungus, Batrachochytrium dendrobatidis, was detected in spray toads that died during the extinction event and subsequently in other amphibian species in Kihansi Gorge and the adjacent Udagaji Gorge, but not in any toads collected prior to this. Following the population decline, the remaining spray toad population gradually disappeared over a nine-month period. We demonstrate how demographic (rare, low fecundity, high elevation species) and behavioural (congregate in high densities) attributes predisposed the spray toads to chytridiomycosis, as a result of B. dendrobatidis infections, and how epidemic disease could have been exacerbated by altered environmental conditions in the spray wetlands. Our results show that chytridiomycosis was the proximate cause of extinction in the wild of N. asperginis. This represents the first known case of extinction by disease of an amphibian species in Africa. Captive breeding programs, in both the US and Tanzania, have been introduced in order to ensure the survival of the species and a reintroduction program is underway. However, we caution that chytridiomycosis remains an existing threat, which requires a comprehensive mitigation strategy before the desired conservation outcome of an established population of repatriated toads can be achieved.

中文翻译:

Kihansi 喷雾蟾蜍 Nectophrynoides asperginis 在野外因疾病而灭绝

摘要 尽管在坦桑尼亚 Kihansi 峡谷对其栖息地进行了种群监测和保护管理,但 Kihansi 喷雾蟾蜍 Nectophrynoides asperginis 在野外已经灭绝。先前的调查表明,人类引起的栖息地改变、捕食者、杀虫剂和疾病可能是导致人口迅速减少和物种灭绝的原因。在这里,我们系统地调查了疾病在野生蟾蜍种群灭绝事件中的作用。两栖类壶菌属 Batrachochytrium dendrobatidis,在灭绝事件期间死亡的喷雾蟾蜍以及随后在 Kihansi 峡谷和邻近的 Udagaji 峡谷的其他两栖动物物种中检测到,但在此之前收集的任何蟾蜍中均未检测到。随着人口的减少,在九个月的时间里,剩余的喷雾蟾蜍种群逐渐消失。我们展示了人口统计(稀有、低繁殖力、高海拔物种)和行为(高密度聚集)属性如何使喷雾蟾蜍易患壶菌病,作为 B. dendrobatidis 感染的结果,以及流行病如何因环境改变而加剧喷雾湿地条件。我们的研究结果表明,壶菌病是野外曲霉孢子菌灭绝的最直接原因。这是非洲已知的首例两栖动物因疾病而灭绝的案例。美国和坦桑尼亚都引入了圈养繁殖计划,以确保该物种的生存,重新引入计划正在进行中。然而,
更新日期:2020-04-24
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