The S. pneumoniae pan-genome according to the power law model. The number of specific genes is plotted as a function of the number (n) of strains sequentially added (see Materials and methods). For each n, points are the values obtained for the different strain combinations; red symbols are the average of these values, and error bars represent standard deviations. The superimposed line is a fit with a decaying power law y = A/nB. The fit parameters are A = 295 ± 117 and B = 1.0 ± 0.15.
Donati et al. Genome Biology 2010 11:R107 doi:10.1186/gb-2010-11-10-r107