Title: Worldwide Phylogeography and Local Population Structure of the Rough-Toothed

Several dolphin species have global distributions. The extent of their radiation and limits to gene flow are presumably a product of oceanographic features both recent and historical, behavioral specializations and social organization. Rough-toothed dolphins (Steno bredanensis) are globally distributed in tropical and subtropical waters and are generally found in depths greater than 1,500 meters making them challenging to comprehensively sample. Although it has been assumed that pelagic dolphins range widely due to the lack of apparent barriers and unpredictable prey distribution, recent evidence suggests rough-toothed dolphins exhibit fidelity to some oceanic islands. A small number of photo-identification and genetic studies conducted to date on rough-toothed dolphins show regional population structure and stable associations in groups, with some individuals observed repeatedly in the same groups over several years. The aim of this dissertation is to describe patterns of phylogeography over evolutionary time on a global scale and expand studies of population and social structure on a regional level. The dataset contains 351 rough-toothed dolphin biopsies, tissue and teeth samples collected from the Pacific and Atlantic Oceans and limited samples from the India