Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians
Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians
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DOI：
10.1111/mec.12385
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发表时间：
2013-08-01
影响因子：
4.9
通讯作者：
Waldman, Bruce
中科院分区：
文献类型：
--
作者：
Bataille, Arnaud;Fong, Jonathan J.;Waldman, Bruce
两栖动物种群的减少和灭绝被归因于壶菌(Batrachochytrium Dendrobatidis，Bd)，特别是一个全球新兴的重组谱系(Bd-GPL)。我们使用针对Bd的核糖体内转录间隔区(ITS)的PCR分析来确定Bd在韩国的患病率和遗传多样性，在韩国，Bd分布广泛，但尚不知道Bd会导致野生种群的发病或死亡。我们从感染负荷较低的本土两栖动物中分离出韩国Bd株，并利用19个SNP和微卫星基因座将它们与世界已知的Bd株进行了比较。在17种朝鲜本土物种中，11种的BD患病率在12.5%到48.0%之间，在引进的牛蛙中，BD的患病率为24.7%。根据ITS序列变异，在50个已鉴定的韩国单倍型中，有47个形成了一个与巴西本土Bd血统密切相关的群体，与Bd-GPL血统分离。然而，三个韩国Bd分离株的多位点基因分型显示出与Bd-GPL和巴西本土Bd血统的强烈差异。因此，ITS区域解决了与Bd-GPL不同的基因类型，但在其他方面产生了不明确的系统发育。我们的结果指出，在亚洲两栖动物物种中存在高度多样化的Bd地方性菌株。Bd-GPL相关单倍型的罕见表明，要么这个血统是最近才被引入韩国的，要么是Bd-GPL已经被当地的Bd株所击败。我们的结果强调了在评估Bd-GPL对全球两栖动物种群的传播和影响时，需要考虑本地Bd血统、Bd-GPL及其相关两栖动物宿主之间可能存在的复杂相互作用。
Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage ('Bd-GPL'). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus. Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations.