Evolutionary rates of insertion and deletion in noncoding nucleotide sequences of primates

Insertions and deletions are responsible for gaps in aligned nucleotidesequences, but they have been usually ignored when the number of nucleotidesubstitutions was estimated. We compared six sets of nuclear andmitochondrial noncoding DNA sequences of primates and obtained theestimates of the evolutionary rate of insertion and deletion. Themaximum-parsimony principle was applied to locate insertions and deletionson a given phylogenetic tree. Deletions were about twice as frequent asinsertions for nuclear DNA, and single-nucleotide insertions and deletionswere the most frequent in all events. The rate of insertion and deletionwas found to be rather constant among branches of the phylogenetic tree,and the rate (approximately 2.0/kb/Myr) for mitochondrial DNA was found tobe much higher than that (approximately 0.2/kb/Myr) for nuclear DNA. Therates of nucleotide substitution were about 10 times higher than the rateof insertion and deletion for both nuclear and mitochondrial DNA.