Saenz Veronica, Byrne Allison Q, Ohmer Michel E B, Hammond Talisin T, Brannelly Laura A, Altman Karie A, Kosowsky Miranda, Nordheim Caitlin L, Rosenblum Erica Bree, Richards-Zawacki Corinne L
Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th and Ruskin Aves., Pittsburgh, PA, 15260, USA.
Department of Biology, The Pennsylvania State University, State College, PA, 16802, USA.
Oecologia. 2024 Dec 7;207(1):3. doi: 10.1007/s00442-024-05642-8.
Aquatic pathogens often cannot tolerate drying, and thus their spread, and diversity across a landscape may depend on interactions between hydrological conditions and the movement of infected hosts. The aquatic fungus Batrachochytrium dendrobatidis (Bd) is a nearly ubiquitous pathogen of amphibians and particular lineages have been associated with host declines. By coupling amphibian surveys with molecular pathogen detection and genotyping techniques, we characterized the spatial dynamics and genetic diversity of Bd on a landscape containing both permanent and ephemeral ponds. In doing so, we aimed to clarify how pathogen loads and prevalences vary across seasons and among habitat types, and which host species move the pathogen from place to place. At the start of spring breeding, Bd prevalence was lower on amphibians sampled from ephemeral ponds. For the remainder of the amphibian active season, prevalence was similar across both ephemeral and permanent ponds, with variation in prevalence being well-explained by a hump-shaped relationship with host body temperature. The first amphibians to arrive at these ephemeral ponds infected were species that breed in ephemeral ponds and likely emerged infected from terrestrial hibernacula. However, species from permanent ponds, most of which hibernate aquatically, later visited the ephemeral ponds and these animals had a greater prevalence and load of Bd, suggesting that migrants among ponds and pond types also move Bd across the landscape. The Bd we sampled was genetically diverse within ponds but showed little genetic structure among ponds, host species, or seasons. Taken together, our findings suggest that Bd can be diverse even at small scales and moves readily across a landscape with help from a wide variety of hosts.
水生病原体通常无法耐受干燥，因此它们在景观中的传播和多样性可能取决于水文条件与受感染宿主移动之间的相互作用。水生真菌蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）是两栖动物几乎普遍存在的病原体，特定谱系与宿主数量下降有关。通过将两栖动物调查与分子病原体检测和基因分型技术相结合，我们对一个既有永久性池塘又有临时性池塘的景观中Bd的空间动态和遗传多样性进行了表征。在此过程中，我们旨在阐明病原体载量和患病率如何随季节以及栖息地类型而变化，以及哪些宿主物种将病原体从一个地方传播到另一个地方。在春季繁殖开始时，从临时性池塘采集的两栖动物身上的Bd患病率较低。在两栖动物活跃季节的其余时间里，临时性池塘和永久性池塘中的患病率相似，患病率的变化可以通过与宿主体温呈驼峰状关系得到很好的解释。最早到达这些被感染的临时性池塘的两栖动物是在临时性池塘繁殖的物种，它们可能从陆地冬眠处出来时就已被感染。然而，来自永久性池塘的物种，其中大多数在水中冬眠，后来访问了临时性池塘，这些动物的Bd患病率和载量更高，这表明不同池塘和池塘类型之间的迁徙者也在景观中传播Bd。我们采样的Bd在池塘内具有遗传多样性，但在池塘、宿主物种或季节之间几乎没有遗传结构。综合来看，我们的研究结果表明，即使在小尺度上，Bd也可能具有多样性，并且在各种宿主的帮助下能够很容易地在景观中移动。
