Metrics
74 File views/ downloads
38 Record Views
Thesis
POPULATION STRUCTURE AND PHYLOGENETICS OF ATLANTIC AND CARIBBEAN SHARPNOSE SHARKS (GENUS RHIZOPRIONODON)
University of West Florida
Master of Science (MS), University of West Florida
2017
Abstract
Members of the genus Rhizoprionodon are small coastal requiem sharks that occur in high abundance throughout the waters of the world. The Atlantic sharpnose shark Rhizoprionodon terraenovae is found along the Atlantic seaboard of the United States and in the Gulf of Mexico where it is often caught as commercial bycatch and exploited by artisanal fisheries, though it is considered of least concern to overfishing. Previous research has shown that the larger elasmobranch species display high vagility, or long-range movements, whereas smaller sharks occupy small home ranges, often with significant genetic heterogeneity between regions or basins. Despite this trend, prior work on R. terraenovae has not supported significant genetic heterogeneity between ocean basins. We assessed the genetic population structure of R. terraenovae throughout its range using a highly polymorphic gene, the mitochondrial control region (CR), coupled with intensive sampling to determine if barriers to gene flow exist within this species' range. Our results indicate low but significant population structure between the Gulf of Mexico and the rest of the western Atlantic Ocean, but found no conclusive evidence of genetic structure elsewhere. In the process of assessing R. terraenovae phylogeography, several samples from South Carolina, Virginia, and northern Florida were identified as the Caribbean sharpnose shark Rhizoprionodon porosus. Rhizoprionodon terraenovae and R. porosus share a similar appearance, though their home ranges are thought to be non-overlapping north of the Bahamas. We sequenced the nuclear ribosomal Internal Transcribed Spacer-2 (ITS2) gene to verify the species identification of these specimens, qualified the observed range expansion, and assessed the possibility of hybridization. Our results indicated that these specimens are most likely R. porosus, though a previously-uncharacterized genetic type. In the future, it will be necessary to re-evaluate the northern range of Caribbean sharpnose sharks.
Details
- Title
- POPULATION STRUCTURE AND PHYLOGENETICS OF ATLANTIC AND CARIBBEAN SHARPNOSE SHARKS (GENUS RHIZOPRIONODON)
- Resource Type
- Thesis
- Publisher
- University of West Florida
- Format
- text
- Identifiers
- 99380090860006600
- Academic Unit
- Biology
- Language
- English
- Awarding Institution
- University of West Florida; Master of Science (MS)
- Theses and Dissertations
- Master of Science (MS), University of West Florida