AimEcological theory suggests that dispersal limitation and selection by climatic factors influence bacterial community assembly at a continental scale, yet the conditions governing the relative importance of each process remains unclear. The carnivorous pitcher plant Sarracenia purpurea provides a model aquatic microecosystem to assess bacterial communities across the host plant's north–south range in North America. This study determined the relative influences of dispersal limitation and environmental selection on the assembly of bacterial communities inhabiting S. purpurea pitchers at the continental scale.LocationEastern United States and Canada.Time Period2016.Major Taxa StudiedBacteria inhabiting S. purpurea pitchers.MethodsPitcher morphology, fluid, inquilines and prey were measured, and pitcher fluid underwent DNA sequencing for bacterial community analysis. Null modelling of β‐diversity provided estimates for the contributions of selection and dispersal limitation to community assembly, complemented by an examination of spatial clustering of individuals. Phylogenetic and ecological associations of co‐occurrence network module bacteria was determined by assessing the phylogenetic diversity and habitat preferences of member taxa.ResultsDispersal limitation was evident from between‐site variation and spatial aggregation of individual bacterial taxa in the S. purpurea pitcher system. Selection pressure was weak across the geographic range, yet network module analysis indicated environmental selection within subgroups. A group of aquatic bacteria held traits under selection in warmer, wetter climates, and midge abundance was associated with selection for traits held by a group of saprotrophs. Processes that increased pitcher fluid volume weakened selection in one module, possibly by supporting greater bacterial dispersal.ConclusionDispersal limitation governed bacterial community assembly in S. purpurea pitchers at a continental scale (74% of between‐site comparisons) and was significantly greater than selection across the range. Network modules showed evidence for selection, demonstrating that multiple processes acted concurrently in bacterial community assembly at the continental scale.

中文翻译：

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在大陆尺度上，传播限制控制北方猪笼草植物 （Sarracenia purpurea） 中的细菌群落组装


Aim生态学理论表明，气候因素的传播限制和选择影响了大陆尺度的细菌群落组装，但控制每个过程相对重要性的条件仍不清楚。食肉猪笼草植物 Sarracenia purpurea 提供了一个模型水生微生态系统，用于评估北美寄主植物南北范围内的细菌群落。本研究确定了传播限制和环境选择对大陆尺度上栖息着 S. purpurea 笼子的细菌群落组装的相对影响。地点美国东部和加拿大.时间段2016.主要分类群研究栖息在 S. purpurea 笼子中的细菌。方法测量笼子形态、液体、询问线和猎物，并进行 DNA 测序笼子液进行细菌群落分析。β多样性的零建模为选择和扩散限制对群落组装的贡献提供了估计，并辅以对个体空间聚类的检查。通过评估成员分类群的系统发育多样性和栖息地偏好，确定共现网络模块细菌的系统发育和生态关联。结果从 S. purpurea 笼系统中单个细菌分类群的位点间变异和空间聚集中可以明显看出扩散限制。选择压力在整个地理范围内较弱，但网络模块分析表明亚组内的环境选择。一组水生细菌在温暖、潮湿的气候中具有选择下的性状，而蠓的丰度与一组腐生菌所具有的性状的选择有关。 增加笼子液体积的过程削弱了一个模块中的选择，可能是通过支持更大的细菌扩散。结论在大陆尺度上（74% 的位点间比较）传播限制控制着紫花血吸虫笼中的细菌群落组装，并且明显大于整个范围内的选择。网络模块显示了选择的证据，表明多个过程在大陆尺度的细菌群落组装中同时起作用。