Walton, Which Sponsored Me at the Project's Origin during Summer 2004). I Also Thank William Zawiski for Collection Help. Collections Were Made under Scientific Collection Permits from the States of Michigan and Ohio. Members of the Great Lakes Genetics

An Abstract of Molecular, morphological, and biogeographic resolution of cryptic taxa in the Greenside Darter Etheostoma blennioides complex DNA sequencing has led to the resolution of many cryptic taxa, which are especially prevalent in the North American darter fishes (Family Percidae). The Greenside Darter Etheostoma blennioides commonly occurs in the lower Great Lakes region, where two putative subspecies, the eastern " Allegheny " type E. b. blennioides and the western " Prairie " type E. b. pholidotum, overlap. The objective of this study was to test the systematic identity and genetic divergence distinguishing the two subspecies in areas of sympatry and allopatry in comparison to other subspecies and close relatives. DNA sequences from the mtDNA cytochrome b gene and control region and the nuclear S7 intron 1 comprising a total of 1,497 bp were compared from 294 individuals across 18 divergences among taxa (θ ST = 0.92 – 0.97; p-distance = 0.025 – 0.039) presently designated as E. b. blennioides, E. b. newmanii, and E. b. pholidotum, as well as identification of a fourth clade in the Meramec River. Most traditional morphological iv characters were significantly different (P= 0.0001) in distinguishing between E. b. blennioides and E. b. pholidotum, including scale counts and degree of ventral squamation. However, the range of variation within these characters overlapped, obscuring accurate assignment of individuals to the taxa. The four significantly divergent taxa of the Greenside Darter complex should be evaluated further for potential elevation to species status. v Acknowledgments I am grateful to my advisor, Dr. Carol Stepien, for her support and mentoring throughout the course of my project. Villet helped with field and laboratory work, and provided a valuable sounding board for ideas and improvements. My committee members Dr. Timothy Fisher and Dr. Johan Gottgens made suggestions that improved both the thesis and manuscript, and Dr. Timothy Fisher helped to determine the distribution of the Greenside Darter during the Pleistocene glaciations. Additional aid was provided by Dr. Peter Berendzen with glacial distribution figures, Dr. Brooks Burr with morphological determination, Dr. David Krantz with Quaternary geological information, Dr. Ann Krause with statistical analyses, and Dr. Brady Porter supplied outgroup samples. Patricia Uzmann provided logistic support. I thank my husband, Michael Bagley, for all of the support he has provided me for the past two years and my family, Arthur, Sheila, and Alexis Haponski, for always pushing me to do my best. Last but …