PNNL

Abstract

Setting the pace of life and constraining the role of members in food webs, body size can affect the structure and dynamics of communities across multiple scales of biological organization (e.g., from the individual to the ecosystem). Its effects on shaping microbial communities, as well as underlying assembly processes, remain poorly known. Here, we analyzed microbial diversity in the largest urban lake in China (i.e., Lake Donghu) and disentangled the ecological processes governing microbial eukaryotes and prokaryotes using molecular techniques. We found that pico/nano-sized eukaryotes (0.22-20µm) and micro-sized eukaryotes (20-200µm) showed significant differences in terms of both community composition and assembly processes even though they were characterized by similar phylotype diversity. We also found scale dependencies whereby micro-sized eukaryotes were strongly governed by environmental selection at the local scale and dispersal limitation at the regional scale. Interestingly, it was the micro-sized eukaryotes, rather than the pico/nano-sized eukaryotes, that shared similar distribution and community assembly patterns with the prokaryotes. This indicated that assembly processes of eukaryotes are coupled or decoupled from prokaryotes assembly processes based on eukaryote body size. While the results support the important influence of body size, they cannot fully isolate body size as the primary driver of assembly process coupling across sub-communities. Additional studies are needed to further evaluate the potential for body size to be a driver of coordinated and divergent community assembly processes across organismal groups.