Resolving ecological drivers of temporal variations of β-diversity across intertidal microbiomes.

Resolving the ecological drivers mediating the diversity patterns of microbial communities across space and through time is a central issue in microbial ecology. Both regional species pools and local community assembly contribute to the spatial turnover of biodiversity. In this study, we extended the concept of regional species pool to temporal, and investigated the seasonal dynamics of intertidal microbiomes across four microbial domains/kingdoms (bacteria, archaea, fungi, and protists). The results showed that the seasonal variations of microbial β-diversity were primarily governed by community assembly processes rather than temporal species pools. Different microbial domains/kingdoms were structured by different ecological processes, with homogeneous selection as the major process for all of them. Additionally, bacteria and fungi were critically shaped by drift, and protists by drift and homogeneous dispersal. Among various factors, temperature was important in shaping the temporal patterns of microbial β-diversity. The fluctuation in temperature was strongly associated with fungi and protists, resulting in high drift of community composition. This study demonstrated that community assembly processes governed the dynamic seasonal β-variations of intertidal microbiomes, expanding our understanding from spatial ecology.