Longo Ana V, Zamudio Kelly R
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA.
Mol Ecol. 2017 Sep;26(18):4787-4797. doi: 10.1111/mec.14220. Epub 2017 Aug 2.
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.
与宿主相关的皮肤细菌群落作为抵御入侵病原体的第一道防线。然而，对于大多数自然系统而言，我们尚不清楚温度变化如何影响皮肤细菌群落的结构和组成，进而促进或限制机会性病原体的定殖。在此，我们研究了在受到致病性真菌蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）感染的三个两栖动物种群中，自然温度波动如何随时间与皮肤细菌多样性的变化相关联。我们重点研究的宿主物种（寇氏雨蛙，Eleutherodactylus coqui）是一种直接发育的蛙类，在过去20年中，其一些种群数量有所下降，而其他种群则未发生任何变化。我们在四个采样时间点对皮肤细菌的α多样性和β多样性进行了量化，这一时期涵盖两个季节，自然感染和环境条件存在很大差异。尽管不同种群的感染模式不同，但我们检测到细菌多样性随时间总体呈增加趋势，其特征是细菌操作分类单元（OTU）的更替。蛙体温的升高可能使细菌得以定殖，以及部分指示OTU的招募，这可能促进了观察到的多样性模式变化。我们的结果表明，自然环境波动可能为细菌更替创造了机会，潜在地减弱了病原体传播，从而有助于寇氏雨蛙种群中宿主的存续。
