An Analysis of Gene Regulatory Evolution Within the Centrarchids
Parker, Henry Randolph
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https://hdl.handle.net/2142/77640
Description
Title
An Analysis of Gene Regulatory Evolution Within the Centrarchids
Author(s)
Parker, Henry Randolph
Issue Date
1984
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, General
Language
eng
Abstract
Three different studies analyzed the divergence of developmental regulation among centrarchid fishes (Centrarchidae, Perciformes). The degree of divergence between the regulatory genes of different species was assessed investigating the extent to which morphological and molecular development is altered in hybrid embryos. The degree of gene regulatory divergence between species was compared to the amount of divergence in their structural genes. The first study focused on the degree of altered gene expression in hybrid embryos formed by crossing the males of 10 different species with the female Micropterus salmoides floridanus. A positive correlation was detected between increasing genetic distance, D (Nei, 1978), between parental species (ranging from D = 0.133-0.974) and the developmental success of the hybrids at several levels: (1) hatching percentages, (2) temporal regulation of enzyme activity (15 loci), and (3) the levels of enzyme specific activities (15 loci) throughout development. With one exception (Lepomis microlophus), the extent of gene regulatory divergence between species is strongly correlated with their divergence times.
The second study similarly investigated the relationships between structural gene and regulatory gene divergences among species within one genus (Lepomis). The Lepomis cyanellus served as the maternal species in the hybrid crosses with males of three other species. Only the degree of perturbations of enzyme activity levels over development was correlated with divergence time between the parents. The lack of a significant correlation of the time of first enzyme appearance, first activity increase, or hatching success of the hybrids with the genetic distance between parental species suggests a partial uncoupling of structural and regulatory gene evolution in some species' lineages.
The third study investigated developmental patterns of enzyme locus expression within two subspecies of Micropterus and their reciprocal hybrids, in order to determine the extent that gene regulatory divergence can occur between populations within a species. During embryogenesis of the four classes of embryos, many differences in the times of first gene expression, as well as in absolute levels of enzyme activities (16 loci), were observed. The mutational differences between the two subspecies which effect developmental processes is evidence of the ongoing divergence of gene regulation which may eventually play an important role in their reproductive isolation.
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