Conservation versus parallel gains in intron evolution.
Orthologous genes from distant eukaryotic species, e.g. animals and plants, share up to 25-30% intron positions. However, the relative contributions of evolutionary conservation and parallel gain of new introns into this pattern remain unknown. Here, the extent of independent insertion of introns in the same sites (parallel gain) in orthologous genes from phylogenetically distant eukaryotes is assessed within the framework of the protosplice site model. It is shown that protosplice sites are no more conserved during evolution of eukaryotic gene sequences than random sites. Simulation of intron insertion into protosplice sites with the observed protosplice site frequencies and intron densities shows that parallel gain can account but for a small fraction (5-10%) of shared intron positions in distantly related species. Thus, the presence of numerous introns in the same positions in orthologous genes from distant eukaryotes, such as animals, fungi and plants, appears to reflect mostly bona fide evolutionary conservation.
Sverdlov
Alexander V
AV
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health 8600 Rockville Pike, Bldg 38A, Bethesda, MD 20894, USA.
Rogozin
Igor B
IB
Babenko
Vladimir N
VN
Koonin
Eugene V
EV
D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006801:Humans; D007438:Introns; D008957:Models, Genetic; D022821:RNA Splice Sites
D022821:RNA Splice Sites