Jan 25 2019

E&E PhD Disseration Seminar: Biogeography, Diversification, and Domestication in the Coca Family (Erythroxylaceae), Dawson White

January 25, 2019

12:00 PM - 1:00 PM


4289 SEL


840 West Taylor, Chicago, IL 60607

Abstract: The coca family is most infamously known as the natural source of cocaine, isolated from four South American taxa called coca, but it also comprises 283 more species of trees and shrubs distributed in tropical habitats throughout the world. My research utilizes DNA sequence data primarily obtained from herbarium collections to chronicle the diversification of this clade in space and time, thus answering fundamental questions about the geographic origin, dispersal, and diversification patterns that have shaped its current diversity and distribution. This macroevolutionary chronology also details the ecological evolution of the clade by quantifying the distributions of species in tropical dry forest, rainforest, and savanna/grassland biomes and characterizing the frequencies and directions of biome transitions associated with speciation. The taxonomic sampling of this study has also enabled identification of the closest wild relatives of the cultivated coca taxa. This result has been extended into a population-level analysis revealing multiple independent origins of the coca crop in South America. Coca has been created from a genetically diverse and widespread Amazonian Erythroxylum species two or three times, supporting a paradigm that different Holocene peoples were able to breed the same natural resource into domestication to serve their needs; in this case, a mild workaday stimulant and medicine.

Faculty advisor: Robie Mason-Gamer


Suzanne Harrison

Date posted

Jan 4, 2019

Date updated

Jan 17, 2019