Significant advances have been made towards surveying animal and plant communities using DNA isolated from environmental samples. Despite rapid progress, we lack a comprehensive understanding of the “ecology” of environmental DNA (eDNA), particularly its temporal and spatial distribution and how this is shaped by abiotic and biotic processes. Here, we tested how seasonal variation in thermal stratification and animal habitat preferences influences the distribution of eDNA in lakes. We sampled eDNA depth profiles of five dimictic lakes during both summer stratification and autumn turnover, each containing warm- and cool-water fishes as well as the cold-water stenotherm, lake trout (Salvelinus namaycush). Habitat use by S. namaycush was validated by acoustic telemetry and was significantly related to eDNA distribution during stratification. Fish eDNA became “stratified” into layers during summer months, reflecting lake stratification and the thermal niches of the species. During summer months, S. namaycush, which rarely ventured into shallow waters, could only be detected at the deepest layers of the lakes, whereas the eDNA of warm-water fishes was much more abundant above the thermocline. By contrast, during autumn lake turnover, the fish species assemblage as detected by eDNA was homogenous throughout the water column. These findings contribute to our overall understanding of the “ecology” of eDNA within lake ecosystems, illustrating how the strong interaction between seasonal thermal structure in lakes and thermal niches of species on very localized spatial scales influences our ability to detect species.

中文翻译：

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热分层和鱼类热偏好解释了湖泊中的垂直 eDNA 分布

在使用从环境样本中分离的 DNA 调查动植物群落方面取得了重大进展。尽管进展迅速，但我们对环境 DNA (eDNA) 的“生态学”缺乏全面的了解，尤其是它的时空分布以及非生物和生物过程如何塑造它。在这里，我们测试了热分层和动物栖息地偏好的季节性变化如何影响湖泊中 eDNA 的分布。我们在夏季分层和秋季更替期间对五个双叠层湖泊的 eDNA 深度剖面进行了采样，每个湖泊都包含温水和凉水鱼类以及冷水鱼、湖鳟鱼 ( Salvelinus namaycush )。S. namaycush 对栖息地的利用经声学遥测验证，与分层过程中的 eDNA 分布显着相关。在夏季月份，鱼类 eDNA 变得“分层”成层，反映了湖泊分层和该物种的热生态位。在夏季，S. namaycush很少涉足浅水区，只能在湖泊的最深处检测到，而温水鱼类的 eDNA 在温跃层上方更为丰富。相比之下，在秋季湖泊周转期间，eDNA 检测到的鱼类组合在整个水体中是同质的。这些发现有助于我们全面了解湖泊生态系统内 eDNA 的“生态学”，说明湖泊中的季节性热结构与非常局部空间尺度上物种的热生态位之间的强相互作用如何影响我们检测物种的能力。