Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Stacey D. Smith

Second Advisor

Erin Tripp

Third Advisor

Christy McCain

Fourth Advisor

Pamela Diggle

Fifth Advisor

Daniel Doak

Abstract

My dissertation examines how the interplay between historical biogeographic events and environmental factors shaped species distributions and traits in the tomato family (Solanaceae). Historical biogeographic analyses were undertaken at a broad evolutionary scale level, considering the entire Solanaceae family (Chapter 1). To address environmental factors and plant traits, I then focused my work on a smaller group within Solanaceae, the tribe Datureae. Within this clade, I estimated the evolutionary relationships between its 18 extant species (Chapter 2), assessed environmental niche evolution of the different genera (Chapter 3) and evaluated changes in the plant’s morphology, specifically fruit morphology, related to dry and mesic environments (Chapter 4). My work demonstrated that South America is the ancestral area for Solanaceae, and dispersal was the principal driver of range evolution in the family. Most dispersals involved range expansions from South America into North and Central America, a trend that is likely due to the early build-up of species richness in South America, resulting in large pool of potential migrants. For Datureae, phylogenetic and biogeographic analyses point to an origin in the Andes of South America, with subsequent expansion to North America and other regions in South America. I also found that the ancestral environmental niche in the tribe is dry and that there has been a significant shift in one South American lineage towards a more mesic environment. Finally, my work showed an accumulation of morphological changes in the North American lineage of Datureae. In particular, this lineage (the genus Datura) evolved dehiscent capsular fruits from the ancestral state (berries) through a complex series of anatomical changes. Placing this work in a comparative developmental context, this work revealed the effect of ancestry on the trajectory of fruit evolution.

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