Doctoral Dissertations

Date of Award

5-2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Brian C. O'Meara

Committee Members

Daniel S. Simberloff, Sally P. Horn, James A. Fordyce, Haileab Hilafu

Abstract

Two key processes that have been modeled in a phylogenetic comparative framework are diversification and historical biogeography. Many questions arise on what process have shaped the abundance (or lack) of species we see today and what influences their survival and interconnectedness with other species. Many methods have been developed to answer these questions. Over the past several decades there has been a rise in parametric modeling and development of more adequate frameworks to answer biological questions of interest. However, many models still lack the incorporation of ecological, mainly biotic factors, which influence the evolution and ecology of species, while accounting for phylogenetic relatedness.

In my dissertation, I studied a diverse set of questions in the realm of diversification and biogeography. I began my investigation by improving upon the widely used Dispersal-Extinction and Cladogenesis model and showing my method DEC* is a more adequate model that usually has better model fit and parameter estimation (Chapter 1). I then moved on to learn how a complex trait such a parasitism could influence the diversification of parasitic angiosperms with a wide array of diversification models in phylogenetics (Chapter 2). My results indicated that all parasitic flowering plants are not undergoing an evolutionary dead end, as many have postulated. In my final chapter, I merged trait and biogeographic evolution by assembling a model that would test the influence of body size in passerine birds. Additionally, I tested the influence of several traits upon the diversification of passerine birds (Chapter 3). The results showed that the larger body sizes are not associated with greater dispersal rates in passerines. According to the results, smaller birds have a greater rate of dispersal. I also show support for both body size and region of occurrence in the world (temperate versus tropical) as having an influence on diversification. For the diversification analyses in Chapter 2 and 3, I find evidence of underlying biological trait and/process influencing the diversification of these groups.

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