EVOLUTION OF PATTERNS OF DIFFERENTIAL GENE-EXPRESSION - COMPARISON OF THE TEMPORAL AND SPATIAL PATTERNS OF ISOENZYME LOCUS EXPRESSION IN 2 CLOSELY RELATED FISH SPECIES (NORTHERN LARGEMOUTH BASS, MICROPTERUS-SALMOIDES-SALMOIDES, AND SMALLMOUTH BASS, MICROPTERUS-DOLOMIEUI)

The timing of the onset of developmental expression of 33 loci encoding various enzymes and isozymes was determined for 2 closely related species of fish, M. salmoides salmoides, and M. dolomieui. The patterns of gene expression among the different tissues in adults were also investigated. The tissue and developmental expressions of enzymes and isozymes were visualized by histochemical staining after starch gel electrophoresis. The differential expression of homologous loci within and among the different adult tissues of these 2 related species is virtually identical. The ontogenetic times of expression during the embryogenesis of both species are also quite similar for these same homologous loci. The ontogenetic patterns of differential gene expression for the 2 spp. differ somewhat from those of a more distantly related species within the family Centrarchidae, the green sunfish, Lepomis cyanellus. The hypothesis that there is an increase in divergence of gene expression in species which are progressively more distantly related is supported.