Comparative Molecular Systematics of Select Amphibians and Reptiles
Maha, George Christopher
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https://hdl.handle.net/2142/77632
Description
Title
Comparative Molecular Systematics of Select Amphibians and Reptiles
Author(s)
Maha, George Christopher
Issue Date
1982
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
The use of molecular techniques for determining phylogenetic relationships has become widespread in the last decade. This study examines the reliability of some of these molecular techniques, particularly micro-complement fixation (MC'F), in select amphibians and reptiles.
Studies of the salamander Plethodon glutinosus tested the applicability of MC'F to population analysis. The MC'F results were compared to independent data obtained from gel electrophoresis. Genetic distances determined by both techniques showed a good correlation. The use of both techniques revealed more variation at the albumin locus than detected by either technique alone.
North American colubrid snakes were surveyed with MC'F and numerous problems with current classifications were detected. These problems can be attributed to the limited choice of characters available for comparative morphological analyses. All of the molecular data discussed in this study consistently indicate the same relationships. Additional congruence of divergence dates for various snake lineages was observed using the albumin and transferrin molecular clocks. Two albumin-like components were found in snake plasma. Estimates of molecular weights were determined. Problems these additional molecules may pose for phylogenetic analysis are discussed.
Phylogenetic trees for the snakes were constructed using two different techniques. Each technique yielded a different topology. In order to evaluate these trees, biological criteria and goodness of fit measures were employed. The optimized goodness of fit measures correlated with deviations from equal rates of evolution along different lineages. Thus the use of some of these goodness of fit criteria are questioned.
Hemoglobin was studied as a molecular probe in lineages of North American Bufo. Hemoglobin was not a good immunogen and the data yielded poor reciprocal values. Difficulties in the data precluded detailed phylogenetic analysis.
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