ABSTRACT: The chytrid fungus Batrachochytrium dendrobatidis (Bd) infects numerous amphibian species worldwide and is suggested to drive population declines and extinction events. We report a study of Bd infection at the northernmost distribution of the European yellow-bellied toad Bombina variegata. A total of 577 individuals from ponds in 16 study sites were sampled for DNA and Bd throughout the breeding season. Microsatellite genotyping revealed 3 genetic clusters for the host B. variegata with an overall low genetic diversity. One of the clusters displayed a low microsatellite heterozygosity, a high inbreeding coefficient as well as high Bd infection prevalence and intensities. Multi-model estimates identified site, time of sampling, and heterozygosity to be important predictors of an individual’s Bd infection status, and identified a strong effect of site on individual Bd infection intensity. The study site effects are suggestive of localized infection peaks, and the increase of individual Bd infection probabilities towards the end of the sampling period suggests cumulative infection during the breeding season. This study highlights the need for regular monitoring of Bd infection variables at multiple localities and times to gain insights into Bd dynamics. Due to the detected relationship between individual Bd infection status and heterozygosity, conservation measures should focus on the maintenance of high genetic diversity and connectivity within and among amphibian populations.

中文翻译：

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地点，时间和杂合度影响黄腹蟾蜍的糜蛋白酶感染

摘要：chychyd真菌Batrachochytrium dendrobatidis（Bd）感染了全世界许多两栖动物，并被认为是导致种群减少和灭绝事件的原因。我们报告了对欧洲黄腹蟾蜍Bombina variegata最北端分布的Bd感染的研究。在整个繁殖季节，对来自16个研究地点的池塘中的577个人进行了DNA和Bd采样。微卫星基因分型显示了宿主杂色芽孢杆菌的3个遗传簇，总体遗传多样性较低。其中一个集群显示出低的微卫星杂合度，高的近交系数以及高的Bd感染的发生率和强度。多模型估计确定了位点，采样时间和杂合度，这些都是对个体Bd感染状况的重要预测指标，并且确定了位点对个体Bd感染强度的强烈影响。研究地点的影响暗示了局部感染高峰，并且在采样期末个体Bd感染概率的增加表明在繁殖季节累积感染。这项研究强调需要定期监测多个地方和时间的Bd感染变量，以深入了解Bd动态。由于检测到各个Bd之间的关系 感染状况和杂合性，保护措施应侧重于维持两栖动物种群内部和之间的高度遗传多样性和连通性。