The number and rate of intron loss and gain in fission yeasts.

aSpecies name abbreviations: S. cryophilus (Scry), S. octosporus (Soct), S. pombe (Spom).bOnly introns that were not filtered out by our criteria were counted, including conserved introns and unique introns. Therefore, they are smaller than the total numbers of annotated introns.cThe divergence time between each species and the nodes were obtained from [47]. Data are shown in millions of years.dIntrons lost or gained at the ancestor nodes were counted only once.eThe rates of intron loss are shown as number of lost introns per year per intron.