cm apart within minutes: tens of meters apart within an hour: a few km apart within a week
||Cyanobacteria Prochlorococcus spp.
||Kashtan N et al., Single-cell genomics reveals hundreds of coexisting subpopulations in wild Prochlorococcus. Science. 2014 Apr 25 344(6182):416-20. doi: 10.1126/science.1248575. p.419 middle column top paragraphPubMed ID24763590
||For details of calculation see Supplementary Materials p.20-21 link , bottom paragraph therein: "To summarize, in characteristics upper ocean water ’just-divided’ Prochlorococcus cells will not be within the same milliliter of water within minutes, will be tens of meters apart within one hour, and will be a few kilometers away within a week."
||P.419 left column bottom paragraph: "Enormous population sizes and immense physical mixing probably played a role in the evolution of diverse genomic backbones in Prochlorococcus. A simple fluid mechanics model bridging the micrometer and kilometer scales for a typical ocean suggests that just-divided cells will be centimeters apart within minutes, tens of meters apart within an hour, and a few kilometers apart within a week (ref 15). Thus, Prochlorococcus populations are expected to be well mixed over large water parcels (~10 km^2 area by 3 m depth) on ecologically relevant time scales (~1 week) (ref 15). This mixing and a stable collective Prochlorococcus population density of 10^7 to 10^8 cells liter^−1 (BNID 113304) make the size of each backbone subpopulation in such parcels enormous (>10^13 cells) (ref 15). The effective population size is arguably close to this census population size (ref 15), implying that Prochlorococcus evolution is governed by selection, not genetic drift [based on population genetics theory (ref 26)]. Consistent with this argument, the difference in the observed FST [whole genome population differentiation estimator] distribution from that estimated for no selection (Fig. 3B) provides further evidence that the differentiation of genomic backbones in Prochlorococcus is a product of selection (ref 15)." ref 15="Materials and methods are available as supplementary materials on Science Online."