Browsing by Subject "Bottlenose Dolphin"

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    Geospatial Analysis and Comparison of Habitat Costs for Resident Sarasota Bay Bottlenose Dolphins (Tursiops truncatus)
    (2014-04-24) Carnal, Boyd
    The Sarasota Dolphin Research Program (SDRP) studies a resident Florida bottlenose dolphin population that faces many threats from human activities. These dolphins concentrate in different areas seasonally, possibly in response to changes in the distribution of prey or predators. Movement from one location to another involves certain “costs” to the dolphins, which are defined in this project as the potential for negative environmental interactions (natural and anthropogenic). Using an updated habitat map for the SDRP study area and a geoprocessing model, a cost analysis was performed in order to compare the cost values of eight primary habitat types. Results indicated that Mangrove and Channel are the most costly, while Open Bay and Pass are the least costly. I hypothesized that dolphins will use habitats with lower costs more frequently than habitats with higher costs, but previous research and SDRP photographic survey data show that these dolphins frequently use dredged channels to move between areas, and at the population level they do not use any habitat type disproportionately to its availability.
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    Population Genomics of Bottlenose Dolphins (Tursiops truncatus) in the Northwest Atlantic
    (2021-04-30) Shintaku, Nikki
    Bottlenose dolphins (Tursiops truncatus) are widely accepted as belonging to one of two ecotypes: offshore or inshore. These ecotypes exhibit remarkable differences in ecology, morphology, and genetic diversity. However, regional patterns of genetic differentiation and stock delineation remain poorly defined for both ecotypes. To improve our understanding of the population structures among these groups we investigated genome-wide genetic variation from 96 biopsy samples collected from bottlenose dolphins in inshore and offshore waters of the northwest Atlantic from North Carolina to Florida using restriction site associated DNA sequencing to infer population structure. Analysis of 14,783 single nucleotide polymorphisms revealed at least three genetically differentiated populations. Our results suggest an inshore population along North Carolina’s Outer Banks (n=32), an offshore population off the continental shelf break from North Carolina to Jacksonville, Florida (n= 38), and a shelf population off Jacksonville, Florida (n=26). Bayesian clustering showed significant admixture between the North Carolina and Jacksonville populations, providing potential evidence of historical or current gene flow. Most of the offshore samples were collected off Cape Hatteras, but this population also includes four individuals sampled beyond the continental shelf break off Jacksonville, FL, in close spatial proximity to shelf animals. This suggests a sharp distinction between shelf and offshore individuals structured by the shelf break itself. Such habitat heterogeneity is likely a driver in diversifying populations through influences on social behavior and foraging strategies. Our analyses provide fine-scale genetic resolution of bottlenose dolphin population differentiation in the Western North Atlantic. These results help inform conservation management and advance our understanding of processes that may drive the evolution of population genetic structure.