Allelic expression and genetic distance in hybrid macaque monkeys

Levels of structural genic divergence at 21 loci encoding blood proteins were quantified in six macaque (Macaca) species, using standard techniques of starch-gel electrophoresis. Genetic distances between all pairs of species fall within a narrow range (0.080 less than or equal to D less than or equal to 0.250; D = 0.164) which is near the lower limit of genetic distances typically observed between other congeneric organisms. In an effort to measure levels of regulatory gene differences between these species, we have examined the patterns of allelic expression in their F1, F2, and backcross hybrids. Nine of the 21 loci examined encode allelic forms of the proteins with different electrophoretic mobilities in at least some of the individual parents of the hybrids. In all cases where expected, hybrids express fully both maternal and paternal allelic products, thus providing no strong evidence ofr a breakdown in the regulatory mechanisms responsible for proper expression of these genes. Results are compared to degrees of allelic repression previously observed in other hybrids, and are discussed within the context of current ideas about rates of regulatory gene evolution in mammals.