Research and teaching

Dawson's Science Adventure

My science has, and continues to be, developed through independently designed, high-impact systematic research grounded in collections-based morphological and genomic analyses. A botanical internship in Peru in 2007 gave me my first crash-course in plant collection, floristics, systematics, and herbarium processing, and set my path of botanical research and scholarship. Following other botany jobs in Colorado and Alaska and a B.S. from Colorado State University, I have completed a PhD and two postdoctoral research fellowships, and I am now in my third postdoc at the Harvard University Herbaria.

My PhD thesis and a major part of my ongoing research focuses on the biogeography and diversification of the coca family. The broad goal is to understand how the clade has moved across the globe in space and time as it diversified into about 300 modern species, and what ecological axes and characteristics helped to define this evolutionary history.

This image is derived from a figure in White et al. (2019), wherein I published the first phylogeny (evolutionary history) of this plant group from DNA sequences, gaining insight into how this clade has diversified into different geographical and ecological regions. This work began with Hyb-Seq data and species continue to be added with whole genome resequencing. There are now over 220 species in the Erythroxylaceae phylogeny out of the approximately 300 species. I continue to build this dataset but a primary goal for 2024 is to finally publish my comprehensive biogeographic analysis.

Constructing a genome for coca has been a central part of this research program, and thanks to collaborations with Iridian genomes, we sequenced, assembled, and published the first two coca genomes as well as genomes from 56 wild Erythroxylum species in 2022. I continue working to improve these assemblies to study their architecture and composition.

A fundamental revision of the domestication of coca was recently published in Systematic Biology. Using the hybridization-based exon-capture (Hyb-seq) method to sequence and analyze 424 genes, my colleagues and I studied the genetic diversity and relationships of the four varieties of coca and their two closest wild relatives, finding that Erythroxylum gracilipes (outlined in green) was the source plant of two or three independent domestication events that created the coca crops. This reveals that different ancient South Americans transformed the same wild resource (E. gracilipes) in parallel to create a primary commodity. It is clearly a useful plant!

This project was expanded through an NSF Postdoctoral Research Fellowship in Biology (2021-2022,) and continues in my current position at Harvard (2023-2024).

Cutest leaf award: Dryas ajanensis .

Postdoc research with Rick Ree (Grainger Bioinformatics Center, Field Museum), Dudu Meireles (U. of Maine) and Peter Nelson (Schoodic Institute) in 2019-2020 sent me back to Alaska to study the phylogeography of Alaskan Dryas, and more! After inferring the population structure of ecotypes D. alaskensis and D. ajanensis, we successfully trained algorithms to use leaf spectral reflectance profiles to classify leaves by species, hybrids, and mountaintop populations; learn more in New Phytologist, and watch the Discovery Files episode.

But there is a problem when studying the enigmatic, widespread Arctic dwarf shrub called Dryas: in order to communicate able the plants we were studying, we had to choose among several valid taxonomic names. Dryas is a taxonomic mess because there are three valid naming systems describing 4-26 taxa. The clade is spread across the whole Arctic region and the plants frequently hybridize, producing a gradation of characteristic leaf forms. To fix this problem, I am currently working on a global phylogeny for Dryas to elucidate evolutionary lineages and species boundaries. In collaboration with members of the Natural History Museum at Oslo and the Polish Botanical Institute, we are currently sequencing nearly 400 specimens representing all described taxa across their geographic ranges.

An NSF Postdoctoral Research Fellowship (2021-2022), hosted by Rick Ree and the Negaunee Integrative Research Center at the Field Museum, and collaborating with Dudu Meireles of the University of Maine, is bringing leaf reflectance spectroscopy into the herbarium to see if we can use the bounty of specimens there for spectral taxonomic classification and trait estimation. This fellowship also focused on field collection and genome sequencing for coca phylogeography and domestication, and combining these data with spectra to understand spectral variation and utility for plant systematics. I collected in several regions of Ecuador in 2021 to search for lost coca species and also visited the infamous site of microendemism and exinction, Centinela. In 2022, I completed field work in the Sierra Nevada of Santa Marta with the Arhuaco Nation to collect and learn about their use of coca, or as it is called there, ayu.


NSF PRFB Award #2010821, with reports here.


To improve this research, I have become a partner of the NSF's ASCEND Biology Integration Institute (spectralbiology.org). Thanks to Jeannine Cavender-Bares and the other great researchers at this institution for their efforts to assist with interdisciplinary spectroscopy-based research!

Thanks, plants. And thanks, herbaria.

At the end of 2022, my family and I packed up and moved to Arlington, Massachussets. Now at the Harvard University Herbaria (2023-2024), graciously hosted by Charles Davis, I am continuing my research on the origins of domestication of coca and herbarium spectrometry. The fellowship also allows me to continue my efforts in floristic research and conservation at Centinela in Ecuador. Lots of important papers are in the pipeline. Stay tuned.

Dawson's Teaching Adventure

The bulk of my teaching experience has been as Instructor for the Fundamentals of Genetics Laboratory at the University of Illinois at Chicago (UIC), for which I was given the Award for Excellence in Teaching from the Department of Biological Sciences in 2019, but I have also taught basic STEM concepts through laboratory curriculum for K–2 students in my role as Instructor at the Pinhead Institute in Telluride, Colorado, as well as plant identification and ecological monitoring to 9–12 grade students via the same institution. 

A major benefit of working at the Field Museum is the interface with donors and visitors of all ages.