evolutionary rate

Gillespie JH & Langley CH 1979 Are evolutionary rates really variable? J Mol Evol 13:27-34.

• Langley and Fitch (1973, 1974) concluded that the evolutionary rates of four proteins in vertebrates are temporally variable
• the statistical analysis of Langley and Fitch (L-F) also admits an alternative interpretation
• that evolutionary rates are temporally constant, but that the substitution process is more complex than the Poisson process assumed in the L-F analysis
• this new interpretation motivates a reexamination of the generally accepted view that the neutral allele model of protein evolution (Kimura, 1968) will yield data which are compatible with a Poisson process
• the presently available data may not be incompatible with a constant-rate neutral allele model of evolution