Population genetics, phylogeography, and morphology of Notropis stramineus
Issue Date
2011-12-31Author
Pittman, Kendra J.
Publisher
University of Kansas
Format
143 pages
Type
Dissertation
Degree Level
Ph.D.
Discipline
Ecology & Evolutionary Biology
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This item is protected by copyright and unless otherwise specified the copyright of this thesis/dissertation is held by the author.
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Show full item recordAbstract
Notropis stramineus, also known as the Sand Shiner, is a widespread, common minnow species in eastern North America that inhabits low-gradient streams and lake margins with sand or cobble substrate. The morphology of N. stramineus exhibits a distinct pattern of geographical variation which has compelled authors to recognize two subspecies within this species. In this study, I investigated both the genetic and morphological diversity of N. stramineus. First, I used microsatellite markers to investigate intraspecific genetic variation within a single stream corridor to evaluate population substructure and barriers to dispersal for N. stramineus. Population genetic analyses indicated that there is no genetic structuring between populations of N. stramineus in the Kansas River and that fish in the study area form one panmictic population. Additionally, the two dams within the study area do not appear to restrict dispersal among sample sites. Geographic distance, at least at the scale of this study, also does not appear to be a barrier to dispersal as there was no genetic signal of isolation by distance. Next, I investigated genetic variation across the majority of the distribution of N. stramineus using phylogeographic techniques to test the validity that nominal subspecies are reflective of evolutionary lineages. I also used this data to address hypotheses for the origin of a Texas disjunct population. Phylogeographic analyses rejected the validity of subspecies and instead revealed the existence of five exclusive evolutionary groups, possibly cryptic species, within the nominal N. stramineus. The analyses also support a hypothesis that the disjunct Texas population originated from the Ancestral Plains Stream sometime during the Pleistocene. Finally, I tested the hypothesis that the morphology of the exclusive evolutionary groups in the Great Plains has diverged and is concordant with genetic divergence. Discriminant Function Analysis of 29 morphological shape variables showed that each exclusive evolutionary group in the Great Plains has a unique morphological shape. These findings show that morphological divergence in N. stramineus is concordant with genetic divergence and highly supports the recognition of the exclusive evolutionary groups revealed by phylogeographic analyses as distinct species.
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