First Advisor

Deborah Duffield

Term of Graduation

Fall 1996

Date of Publication


Document Type


Degree Name

Master of Science (M.S.) in Biology






Bottlenose dolphin -- Genetics



Physical Description

1 online resource (vi, 98 pages)


When combined with observational and behavioral data, chromosome variant analysis provides a means of assessing population structure in bottlenose dolphins, Tursiops truncatus. In this cytogenetic analysis of thirty-six bottlenose dolphins, a distribution of fluorescent R-band variants was catalogued and used as a way to characterize the genetic structure of a Tursiops population inhabiting the Matagorda Bay, Texas, area. Three different population genetic analytical techniques were evaluated for their usefulness in analyzing cytogenetic data. The chromosome variant data obtained from this study was then compared with cytogenetic data gathered from a resident dolphin population residing near Sarasota, Florida.

The purpose of this study was to measure the genetic differences that existed within the Matagorda Bay study population, as well as measure the differences which exist when comparing the Matagorda Bay animals to the Sarasota Bay population. The comparison of these two geographically separated populations gave a quantitative baseline from which to evaluate the significance of the level of local differentiation and subgroup structure.

Each population genetic analytical method demonstrated that subgroup differentiation existed within the Matagorda Bay sample. The cytogenetic data, therefore, suggest that the Tursiops in Matagorda Bay most likely do not represent a single breeding unit or population. The Matagorda Bay area could instead be viewed as a region which is inclusive of the home ranges of multiple subgroups of Tursiops. These subgroups of animals presumably interact with one another, and the migration of animals into and out of subgroups serves as a method of genetic exchange among the animals in this region. The extent of migration of animals throughout the Gulf of Mexico is not known, but several chromosome variants previously identified in the Sarasota animals were not present in the Matagorda Bay sample and vice versa.

The cytogenetic data obtained through this study suggests that coastal, in-shore Tursiops populations in the Gulf of Mexico may be best characterized as a series of local, but inter-mixing populations. Chromosomal variants are transmitted from core area to core area via individual animals that do not maintain core area fidelity.


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