Factors shaping community patterns of protists and bacteria on a European scale

Factors shaping community patterns of microorganisms are controversially discussed. Physical and chemical factors certainly limit survival of individual taxa and maintenance of diversity. In recent years, a contribution of geographic distance and of dispersal barriers to distribution patterns of protists and bacteria has been demonstrated. Organismic interactions such as competition, predation and mutualism further modify community structure and maintenance of distinct taxa. Here we address the relative importance of these different factors in shaping protists and bacterial communities on a European scale using high-throughput sequencing data obtained from lentic freshwater ecosystems. We show that community patterns of protists are similar to those of bacteria. Our results indicate that cross-domain organismic factors are important variables with a higher influence on protists as compared to bacteria. Abiotic physical and chemical factors also contributed significantly to community patterns. The contribution of these latter factors was higher for bacteria, which may reflect a stronger biogeochemical coupling. The contribution of geographical distance was similar for both microbial groups. This article is protected by copyright. All rights reserved.