1. Cameron JM (1995) A method for estimating the numbers of synonymous and nonsynonymous substitutions per site. J Mol Evol 41: 1152–1159
2. Easteal S, Collet C (1994) Consistent variation in amino-acid substitution rate, despite uniformity of mutation rate: protein evolution in mammals is not neutral. Mol Biol Evol 11:643–647
3. Eyre-Walker A, Gaut BS (1997) Correlated rates of synonymous site evolution across plant genomes. Mol Biol Evol 14:455–460
4. Gillespie JH (1987) Molecular evolution and the neutral allele theory. Oxf Surv Evol Biol 4:10–37
5. Gillespie JH (1989) Lineage effects and the index of dispersion of molecular evolution. Mol Biol Evol 6:636–647