Honeycutt 9700717 The study is composed of two central objectives. The first objective is to test the hypothesis that the absolute rate of DNA change in a mitochondrial genome is influenced by the mode of replication of the genome. The process of replication yields a displaced strand of DNA. DNA in this displaced single-stranded state is expected to be more susceptible to spontaneous mutation than the normal double-stranded state of the DNA. Thus the hypothesis yields a testable prediction; the amounts of detectable DNA change should be proportional to the time that a DNA strand is displaced during the replication process. The second objective is to use a DNA data set to determine the relationships of a closely related group of Notropin shiners. This group is a member of the most taxonomically diverse family of North American freshwater fishes. Knowledge of these relationships is basic to understanding the taxonomic and ecological diversity of this group. Each objective of this study will be obtained from different analyses of the same mitochondrial DNA data set.