Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

4-27-2015

Graduate Advisor

Robert E. Ricklefs, Ph.D.

Committee

Elizabeth Kellogg

Allison Miller

Patricia Parker

Abstract

My dissertation investigates the demographic history of multiple island populations of several Caribbean bird species through an assessment of contemporary genetic diversity, while inferring relationships between the comparative demography of individual island populations and characteristics of the islands and species. The sizes and distributions of populations vary over time, and episodes of expansion and contraction create characteristic patterns of genetic variation within and among populations. Consequently, contemporary patterns of genetic diversity open a window onto demographic and phylogeographic history. The strength of the study lies in the scale and comprehensiveness of the analysis, encompassing most of the West Indian islands and several species of birds, focusing on populations of 9 species. Methods included amplification and sequencing of mitochondrial DNA, calculation of pairwise genetic distances between and within populations, and coalescence-based estimates of past population sizes. I begin my investigation into the demographic and phylogeographic patterns of West Indian birds with an in-depth analysis of genetic patterns of a clade of tanagers, the Coerebinae, specifically the bananaquit and a group of three species of West Indian bullfinches, as models for investigating the system. These species showed several similarities in their genetic distribution in the archipelago and demographic patterns, which led me to a comparison of several other species to investigate whether general phylogeographic and demographic patterns emerge in an assemblage of birds from the West Indies. Comparative phylogeographic analyses suggest three conspicuous patterns among West Indian birds: 1) populations on Greater Antillean islands are generally distinct from Lesser Antilles, 2) a common phylogeographic break occurs in most species between northern and southern Lesser Antilles populations, particularly between the islands of St. Lucia and St. Vincent, and 3) populations on Barbados are genetically distinct from others in the Lesser Antilles. Demographic trends revealed by coalescence analyses of contemporary genetic diversity are highly variable. Island is not predictive of demographic state of populations, while species identity predicts the demographic history of the West Indian avifauna, indicating that extrinsic factors such as hurricanes, volcanic eruptions, or the localized emergence of diseases do not play a major role in demographic history of West Indian avifauna.

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Biology Commons

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