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Author ORCID Identifier


Open Access Dissertation

Document Type


Degree Name

Doctor of Philosophy (PhD)

Degree Program

Organismic and Evolutionary Biology

Year Degree Awarded


Month Degree Awarded


First Advisor

Ana L. Caicedo

Second Advisor

Lynn S. Adler

Third Advisor

John G. Gibbons

Fourth Advisor

Jason M. Kamilar

Subject Categories



Biologists have long been fascinated by the diversity of fleshy fruits, yet questions remain as to how this variety has evolved. According to the dispersal syndrome hypothesis, flowering plants improved their reproductive success by producing fleshy fruits with appealing combinations of traits that attract animal dispersers. However, animal preferences may not be the only selective pressure driving fruit trait diversity—conflicting forces include damage-inflicting seed predators and pathogens, abiotic habitat conditions, or constraints stemming from non-adaptive mechanical, developmental, or phylogenetic limitations. Few studies have examined the early stages of fleshy fruit evolution across an entire clade of recently diverged plant species. The tomato clade, a group of 14 congeneric species (Solanum sect. Lycopersicon) that includes the cultivated tomato and 13 species of wild relatives, presents an exciting opportunity to fill this gap in our understanding of fruit trait divergence. The system is well studied as a model of fruit development and genetics, providing a stronger knowledge of the molecular underpinnings of traits than is possible with most other fruit systems. Wild tomato species adapted to a range of environments and are known to display multiple fruit colors, sugar profiles, and aromas. However, the extent of fruit trait and genetic diversity across all 13 wild species and the phylogenetic patterns in this variation have not previously been assessed. This dissertation project presents a novel approach and scale to fruit evolution studies using the tomato clade. Specific aims are to: 1) examine the extent and pattern of variation in disperser-relevant ripe fruit phenotypes across wild tomato species and assess whether these traits vary together in syndromes, 2) quantify variation in ripe fruit volatile aroma compounds and their biochemical pathways across the clade as well as whether scent could communicate an honest signal of nutrient content to animal dispersers, and 3) explore patterns of molecular evolution in a set of five genes known to affect different aspects of ripe fruit sugar content and composition in wild tomatoes. In addition to further developing the wild tomato system as a model for fleshy-fruited plant evolution, this research is applicable to plant breeders working on crop improvement.


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Barnett_Dissertation_Appendix_A_TablesA1-A12.xlsx (538 kB)
Appendix A, Tables A1-A12

Barnett_Dissertation_Appendix_B_TablesB1_B7.xlsx (197 kB)
Appendix B, Tables B1-B7

Barnett_Dissertation_Appendix_C_TablesC1-C10.xlsx (117 kB)
Appendix C, Tables C1-C10

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