Honors Program Theses


Open Access Honors Program Thesis

First Advisor

Peter Berendzen


A major challenge for systematists is clearly identifying species early after a speciation event (Frost and Kluge, 1994; Wiens and Servedio, 2000; Coyne and Orr, 2004). Traditionally species delimitation is made based on morphological characteristics, behavioral differences, and/or genetic data. However, for cryptic species lineages, these approaches do not work as well because the lineages have subtle overlapping morphological and behavioral differences and lineage sorting may not be complete (Raxworthy et al., 2007). A far less common approach is to use ecological niche models (ENMs) to help identify new species. This approach holds strong potential for cryptic species in which a consensus has not been reached (e.g., Raxworth et al., 2007). Comparing ENMs of two populations can supply evidence of geographic isolation by revealing areas of unsuitable habitat. This would provide evidence supporting the populations as distinct species because gene flow between the two is unlikely because it would involve migrating across the intervening region of unsuitable habitat. Geographic isolation and areas of unsuitable habitat are indicated by a significantly low degree of niche overlap between the ENMs for each population. A major advantage of using ENMs for species delimitation is it takes environmental data into account which otherwise would be ignored. Therefore, ecological niche models were utilized to address the heated debate as to whether the disjunct clades of the cryptic fish species, Etheostoma blennioides, represent distinct species.

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 (38 pages)