RT Journal Article SR Electronic T1 Homogeneous selection promotes microdiversity in the glacier-fed stream microbiome JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.12.03.409391 DO 10.1101/2020.12.03.409391 A1 Stilianos Fodelianakis A1 Alex D. Washburne A1 Massimo Bourquin A1 Paraskevi Pramateftaki A1 Tyler J. Kohler A1 Michail Styllas A1 Matteo Tolosano A1 Vincent De Staercke A1 Martina Schön A1 Susheel Bhanu Busi A1 Jade Brandani A1 Paul Wilmes A1 Hannes Peter A1 Tom J. Battin YR 2020 UL http://biorxiv.org/content/early/2020/12/03/2020.12.03.409391.abstract AB Microdiversity, the organization of microorganisms into groups with closely related but ecologically different sub-types, is widespread and represents an important linchpin between microbial ecology and evolution. However, the drivers of microdiversification remain largely unknown. Here we show that selection promotes microdiversity in the microbiome associated with sediments in glacier-fed streams (GFS). Applying a novel phylogenetic framework, we identify several clades that are under homogeneous selection and that contain genera with higher levels of microdiversity than the rest of the genera. Overall these clades constituted ∼44% and ∼64% of community α-diversity and abundance, and both percentages increased further in GFS that were largely devoid of primary producers. Our findings show that strong homogeneous selection drives the microdiversification of specialized microbial groups putatively underlying their success in the extreme environment of GFS. This microdiversity could be threatened as glaciers shrink, with unknown consequences for microbial diversity and functionality in these ecosystems.Competing Interest StatementThe authors have declared no competing interest.