The evolution of intron phase distribution in the 684-ortholog dataset. Phase distributions (phase-0:phase-1:phase-2) of introns in modern species (known) are in black. Phase distributions of introns in ancestors (estimated) are in green. Phase distributions of gained and lost introns (estimated) are in red and blue, respectively. All phase distributions are based on events of >90% probability of occurrence. Where there is no such event, phase distributions are not shown. Branches that experienced >1.5 gains per loss are shown in red and those that experienced >1.5 losses per gain are in blue. D. mel, D. melanogaster; A. gam, A. gambiae; C. ele, C. elegans; H. sap, H. sapiens; S. pom, S. pombe; A. tha, A. thaliana; P. fal, P. falciparum.