Long-term endemism of two highly divergent lineages of the amphibian-killing fungus in the Atlantic Forest of Brazil

The recent global spread of the amphibian-killing fungus [Batrachochytrium dendrobatidis (Bd)] has been closely tied to anthropogenic activities; however, regional patterns of spread are not completely understood. Using historical samples, we can test whether Bd was a spreading or endemic pathogen in a region within a particular time frame, because those two disease states provide different predictions for the regional demographic dynamics and population genetics of Bd. Testing historical patterns of pathogen prevalence and population genetics under these predictions is key to understanding the evolution and origin of Bd. Focusing on the Atlantic Forest (AF) of Brazil, we used qPCR assays to determine the presence or absence of Bd on 2799 preserved postmetamorphic anurans collected between 1894 and 2010 and used semi-nested PCRs to determine the frequency of rRNA ITS1 haplotypes from 52 samples. Our earliest date of detection was 1894. A mean prevalence of 23.9% over time and spatiotemp...近年来，致死两栖动物的真菌蛙壶菌（Batrachochytrium dendrobatidis, Bd）在全球范围内的扩散与人类活动紧密相关，但其区域传播模式尚未完全阐明。借助历史样本，我们可验证在特定时间框架内的某一区域中，Bd究竟属于扩散性病原体还是地方性流行病原体——这两种疾病状态会对Bd的区域种群动态与群体遗传学特征给出截然不同的预测结果。基于上述预测验证病原体感染率与群体遗传学的历史模式，是阐明Bd演化与起源的核心关键。本研究以巴西大西洋森林（Atlantic Forest, AF）为研究对象，通过实时荧光定量PCR（qPCR）检测了1894年至2010年间采集的2799份保存完好的变态后无尾两栖类标本的Bd感染情况，并采用半巢式PCR（semi-nested PCR）对52份样本的核糖体RNA ITS1单倍型频率进行了分析。本次检测的最早阳性记录为1894年，整体平均感染率达23.9%，其时空...