Are ocean currents too slow to counteract SAR11 evolution? A next-generation sequencing, phylogeographic analysis.

•SAR11 marine Alphaproteobacteria are among the most abundant heterotrophs on Earth.•So far, the phylogeography of the group has received little attention.•Through quantitative phylogeographic analyses, we show that dispersal limitations are relevant in SAR11 radiation.•In addition, phylogenetic distances between SAR11 communities agreed with divergences predicted by a neutral model.•This is the first study providing empirical evidence of dispersal limitations in ubiquitous and profuse marine bacteria.