The Royal Society, Biology Letters, 6(9), p. 20130849, 2013
Full text: Download
Effective population size (Ne) determines the rate of genetic drift and the relative influence of selection over random genetic changes. While free-living protist populations characteristically consist of huge numbers of cells (N), the absence of any estimates of contemporaryNeraises the question whether protist effective population sizes are comparably large. Using microsatellite genotype data of strains derived from revived cysts of the marine dinoflagellatePentapharsodinium daleifrom sections of a sediment record that spanned some 100 years, we present the first estimates of contemporaryNefor a local population in a free-living protist. The estimates ofNeare relatively small, of the order of a few 100 individuals, and thus are similar in magnitude to values ofNereported for multicellular animals: the implications are thatNeofP. daleiis of many orders of magnitude lower than the number of cells present (Ne/N∼ 10−12) and that stochastic genetic processes may be more prevalent in protist populations than previously anticipated.