Large-scale geographic and climatic factors define the global distribution of freshwater aerobic anoxygenic phototrophic assemblages. Freshwater lakes pufM

Aerobic anoxygenic phototrophs (AAPs) have been show to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and is limited to local investigations. Here, we explore the global occurrence, diversity and distribution of AAPs in lakes covering a wide latitudinal gradient: temperate (Mongolian and German Lakes), tropical (Great East African Lakes) and polar (permanently ice-covered Antarctic lakes) regions. Our results show a widespread distribution of AAPs in lakes with contrasting environmental conditions and confirm that this group is composed of different members of the Alpha- and Betaproteobacteria. While latitude does not seem to strongly influence AAP abundance and richness, clear patterns of community structure and composition along geographic and climatic regions were observed. No cosmopolitan metapopulations were found, suggesting a strong macro-geographical signal in taxonomical AAP composition. Overall, our results suggest that the global distribution patterns of freshwater AAPs are likely driven by a combination of small-scale environmental conditions (specific of each lake and region) and large-scale geographic factors (climatic regions across a latitudinal gradient).