Postprint version. Published in Science, Volume 265, Issue 5175, August 1, 1994, pages 1087-1090.
The definitive version is available at https://doi.org/10.1126/science.8066445.
DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times.
This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution.