Jenkinson T S, Betancourt Román C M, Lambertini C, Valencia-Aguilar A, Rodriguez D, Nunes-de-Almeida C H L, Ruggeri J, Belasen A M, da Silva Leite D, Zamudio K R, Longcore J E, Toledo F L, James T Y
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, 13083-862, Brasil.
Mol Ecol. 2016 Jul;25(13):2978-96. doi: 10.1111/mec.13599. Epub 2016 Mar 21.
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is the emerging infectious disease implicated in recent population declines and extinctions of amphibian species worldwide. Bd strains from regions of disease-associated amphibian decline to date have all belonged to a single, hypervirulent clonal genotype (Bd-GPL). However, earlier studies in the Atlantic Forest of southeastern Brazil detected a novel, putatively enzootic lineage (Bd-Brazil), and indicated hybridization between Bd-GPL and Bd-Brazil. Here, we characterize the spatial distribution and population history of these sympatric lineages in the Brazilian Atlantic Forest. To investigate the genetic structure of Bd in this region, we collected and genotyped Bd strains along a 2400-km transect of the Atlantic Forest. Bd-Brazil genotypes were restricted to a narrow geographic range in the southern Atlantic Forest, while Bd-GPL strains were widespread and largely geographically unstructured. Bd population genetics in this region support the hypothesis that the recently discovered Brazilian lineage is enzootic in the Atlantic Forest of Brazil and that Bd-GPL is a more recently expanded invasive. We collected additional hybrid isolates that demonstrate the recurrence of hybridization between panzootic and enzootic lineages, thereby confirming the existence of a hybrid zone in the Serra da Graciosa mountain range of Paraná State. Our field observations suggest that Bd-GPL may be more infective towards native Brazilian amphibians, and potentially more effective at dispersing across a fragmented landscape. We also provide further evidence of pathogen translocations mediated by the Brazilian ranaculture industry with implications for regulations and policies on global amphibian trade.
壶菌病由真菌蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）引起，是一种新出现的传染病，与全球两栖动物物种近期的数量减少和灭绝有关。迄今为止，来自与疾病相关的两栖动物数量减少地区的Bd菌株均属于单一的高毒力克隆基因型（Bd-GPL）。然而，巴西东南部大西洋森林的早期研究发现了一种新的、据推测为地方性的谱系（Bd-巴西），并表明Bd-GPL和Bd-巴西之间存在杂交。在这里，我们描述了巴西大西洋森林中这些同域谱系的空间分布和种群历史。为了研究该地区Bd的遗传结构，我们沿着大西洋森林2400公里的样带收集并对Bd菌株进行了基因分型。Bd-巴西基因型局限于大西洋森林南部的一个狭窄地理范围，而Bd-GPL菌株分布广泛，在地理上基本没有结构。该地区的Bd种群遗传学支持以下假设：最近发现的巴西谱系在巴西大西洋森林中是地方性的，而Bd-GPL是最近扩展的入侵物种。我们收集了更多的杂交分离株，证明了泛动物疫情谱系和地方性谱系之间杂交的再次发生，从而证实了巴拉那州格拉西奥萨山脉存在杂交带。我们的实地观察表明，Bd-GPL可能对巴西本土两栖动物更具感染力，并且在分散穿越破碎景观方面可能更有效。我们还提供了巴西青蛙养殖业介导病原体转移的进一步证据，这对全球两栖动物贸易的法规和政策具有影响。
