Genetic divergence between rodent species assessed by using two-dimensional electrophoresis.

Abstract

O''Farrell''s technique of 2-dimensional gel electrophoresis (2-DGE) has previously been applied to the study of intrapopulation genetic variation. This approach assays a larger, and in part nonoverlapping, cohort of protein encoding loci compared to conventional 1-dimensional electrophoretic procedures (SGE) and has revealed substantially lower levels of mean heterozygosity. Here this approach is extended to analyze levels and patterns of genetic differentiation between species by using 2-DGE to compare an average of 189 polypeptides between 6 spp. of wild mice [Peromyscus maniculatus, P. leucopus, P. boylii, Ochrotomys nuttalli, Sigmodon hispidus and Mus musculus] representing levels of evolutionary divergence ranging from different subspecies to different families. The magnitude of protein divergence estimated by 2-DGE was on the average only about 1/2 that predicted by SGE. This discrepancy may result from differences in sensitivities between the techniques or differences in the mean level of variation and divergence between the sets of loci assayed by the 2 methods. Nonetheless, the ranking of genetic distances by 2-DGE was identical to that by SGE. The use of the simpler SGE techniques to estimate relative levels of genetic divergence is supported.