Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a devastating infectious disease of amphibians. Retrospective studies using museum vouchers and genetic samples supported the hypothesis that Bd colonized Mexico from North America and then continued to spread into Central and South America, where it led to dramatic losses in tropical amphibian biodiversity (the epizootic wave hypothesis). While these studies suggest that Bd has been in Mexico since the 1970s, information regarding the historical and contemporary occurrence of different pathogen genetic lineages across the country is limited. In the current study, we investigated the historical and contemporary patterns of Bd in Mexico. We combined the swabbing of historical museum vouchers and sampling of wild amphibians with a custom Bd genotyping assay to assess the presence, prevalence, and genetic diversity of Bd over time in Mexico. We found Bd‐positive museum specimens from the late 1800s, far earlier than previous records and well before recent amphibian declines. With Bd genotypes from samples collected between 1975–2019, we observed a contemporary dominance of the global panzootic lineage in Mexico and report four genetic subpopulations and potential for admixture among these populations. The observed genetic variation did not have a clear geographic signature or provide clear support for the epizootic wave hypothesis. These results provide a framework for testing new questions regarding Bd invasions and their temporal relationship to observed amphibian declines in the Americas.

中文翻译：

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墨西哥蝙蝠鱼（Batrachochytrium dendrobatidiidis）的早期存在，在当代全球大流行动物谱系中占主导地位

由真菌杆状芽胞杆菌（Btrachochytrium dendrobatidis，Bd）引起的霉菌病是一种破坏性的两栖动物传染病。使用博物馆凭证和遗传样本进行的回顾性研究支持了Bd从北美殖民到墨西哥，然后继续扩散到中美洲和南美洲的假说，这导致热带两栖动物生物多样性遭受重大损失（流行波假说）。尽管这些研究表明Bd自1970年代以来就在墨西哥，但是有关全国各地不同病原体遗传谱系的历史和当代发生的信息仍然有限。在本研究中，我们调查了Bd的历史和当代模式在墨西哥。我们结合了对历史博物馆凭证的擦洗和野生两栖动物的采样与定制的Bd基因型分析方法，以评估墨西哥Bd在一段时间内的存在，流行和遗传多样性。我们发现了1800年代后期Bd阳性的博物馆标本，远早于以前的记录，并且早于最近的两栖动物下降。带Bd从1975年至2019年收集的样本的基因型中，我们观察到了当代墨西哥在全球动物圈谱系中的主导地位，并报告了这四个种群中的四个遗传亚群和混合潜力。观察到的遗传变异没有明确的地理特征或没有为流行病波假设提供明确的支持。这些结果为测试有关Bd入侵及其与美洲两栖动物数量减少的时间关系的新问题提供了框架。