The Evolution of Gene Expression in The Umbrid Fishes: A Comparison of Phylogenies Based Upon Inferred Differences in Structural and Regulatory Genes (Lactate Dehydrogenase, Duplicate, Controller Nodes, Esocidae, Salmoniformes)

• Main Author: Kettler, Michelle Kathleen
• Format: Text
• Language: unknown
• Published: 1985
• Subjects: Biology; Genetics; Dallia pectoralis
• Online Access: http://hdl.handle.net/2142/77614

224 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985. Genetic distances, based on differences in 51 protein coding structural genes, established relative divergence times among species of mudminnows (Umbridae) and Esox (Esocidae), within the order Salmoniformes. Both cladistic and phenetic analyses support: (1) a close relationship of Umbra limi and U. pygmaea, (2) a closer relationship of Dallia pectoralis to Novumbra hubbsi than to either of the Umbra species, and (3) a closer relationship of the Dallia-Novumbra lineage to species of Esox, than the Umbra lineage is to the Esox. These relationships support some phylogenies based on morphology and karyology, but exclude others. Differences among species with respect to tissue patterns of enzyme locus expression were used to measure divergence at inferred regulatory genes. Enzyme activities for 27 loci in each of six tissues in each of fifteen individuals in each of four species of umbrids were determined using two-fold serial dilutions to visual endpoint. Differences in activity for a given enzyme among tissues and among enzymes in the same tissue were found to be independent. The phylogeny constructed using inferred gene regulatory differences was similar to that based upon inferred structural gene differences. This congruence suggests that a "regulatory clock" exists similar to the molecular clock and that tissue patterns of enzyme locus expression are useful characters for testing systematic and evolutionary hypotheses. Unexpectedly large differences in tissue patterns of gene regulation for one enzyme locus, lactate dehydrogenase-C (Ldh-C), were observed among the umbrid species. The presumed ancestral state of a generalized Ldh-C gene tissue expression has been partially retained in extant primitive species, but has diverged to two highly tissue restricted expressions in more advanced species. The divergence of Ldh-C tissue expression appears to have been proceeding at different rates in different umbrid species lineages and more rapidly than in other fish. The evolutionary canalization of Ldh-C gene regulation from a generalized to a restricted tissue expression in either eye or liver appears to have occurred several times within the bony fishes.