Data from: Temperature variation, bacterial diversity, and fungal infection dynamics in the amphibian skin

Host-associated bacterial communities on the skin act as the first line of defence against invading pathogens. Yet, for most natural systems, we lack a clear understanding of how temperature variability affects structure and composition of skin bacterial communities and, in turn, promotes or limits the colonization of opportunistic pathogens. Here, we examine how natural temperature fluctuations might be related to changes in skin bacterial diversity over time in three amphibian populations infected by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). Our focal host species (Eleutherodactylus coqui) is a direct-developing frog that has suffered declines at some populations in the last 20 years, while others have not experienced any changes. We quantified skin bacterial alpha- and beta-diversity at four sampling time points, a period encompassing two seasons and ample variation in natural infections and environmental conditions. Despite the different patterns of infection across populations, we detected an overall increase in bacterial diversity through time, characterized by the replacement of bacterial operational taxonomic units (OTUs). Increased frog body temperatures possibly allowed the colonization of bacteria as well as the recruitment of a subset of indicator OTUs, which could have promoted the observed changes in diversity patterns. Our results suggest that natural environmental fluctuations might be involved in creating opportunities for bacterial replacement, potentially attenuating pathogen transmission and thus contributing to host persistence in E. coqui populations.

宿主皮肤的共生细菌群落乃是抵御入侵病原体的第一道防线。然而，针对绝大多数自然生态系统，我们仍未明确温度波动如何影响皮肤细菌群落的结构与组成，进而促进或抑制机会性病原体的定殖。本研究针对3个感染了致病蛙壶菌（Batrachochytrium dendrobatidis, Bd）的两栖动物种群，探究自然温度波动与皮肤细菌多样性随时间变化之间的关联。本研究的核心宿主物种为直接发育型蛙类科奎蛙（Eleutherodactylus coqui），该物种的部分种群在过去20年间出现了种群数量下降，而其余种群则未发生明显变化。我们在四个采样时间点对皮肤细菌的α多样性与β多样性进行了定量分析，采样周期涵盖两个季节，且包含自然感染与环境条件的显著波动。尽管不同种群的感染模式存在差异，但我们整体观测到细菌多样性随时间呈上升趋势，其特征为细菌操作分类单元（operational taxonomic units, OTUs）的更替。蛙类体温升高可能促进了细菌的定殖，同时招募了特定的指示性OTU亚群，这或许推动了观测到的多样性模式变化。本研究结果表明，自然环境波动或可为细菌群落更替创造条件，潜在地减弱了病原体的传播能力，进而助力科奎蛙种群的存续。