Honors Program Theses


Open Access Honors Program Thesis

First Advisor

Peter Berendzen


The red-jointed fiddler crab, Uca minax, has a disjunct distribution along the Atlantic and Gulf coasts in North America. Previous studies have not found any significant discrepancies in morphology, physiology, or allozymes between the two groups of U.minax. The primary objective of this study was to use DNA sequence data to test whether genetic variation is consistent with patterns of morphological, physiological, and allozyme variation of the disjunct populations. We collected mitochondrial cytochrome oxidase subunit I and nuclear internal transcribed spacer sequences from approximately 100 individuals distributed across the range. Phylogenetic analyses of the haplotypes revealed no genetic differentiation among the Gulf and Atlantic groups, which is consistent with previous studies. Both genes also showed little variation among individuals. A second objective was to determine how and when these two groups diverged. Based on BEAST and IM analyses, the divergence of the two groups appears to be recent, with massive expansion. These results support the potential for a glacial refugium and subsequent expansion into the current range during the last glacial maximum.

Year of Submission



Department of Biology

University Honors Designation

A thesis submitted in partial fulfillment of the requirements for the designation University Honors


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Date Original


Object Description

1 PDF file (27 pages)