The Plant Press

From The Plant Press, Vol. 26, No. 2, April 2023.

AJ Harris (1978-2023), former Peter Buck postdoctoral fellow

By Jun Wen

Former Smithsonian Botany Peter Buck postdoctoral fellow AJ Harris passed away on January 15, 2023, following a long battle against cervical cancer. She was 44 years old. I was extremely saddened to hear this news from her husband Andrew Dabbs, and with a heavy heart I pass the sad news to her Smithsonian Botany colleagues and to many of her friends.

AJ had an impactful career in the field of plant biogeography and evolution where she developed her research integrating plant phylogenetics, biogeography, and biodiversity informatics. She majored in religious studies as an undergraduate student at North Carolina State University (NCSU) in 2005. She then pursued plant systematics and evolution for her master’s degree at NCSU (2005-2007) with Jenny Xiang as her advisor. She received her doctoral degree in Botany at Oklahoma State University (OSU) in 2015 under the direction of Michael Palmer, with her dissertation research on “Evaluating past and present plant distributions using biodiversity informatics.” I served on her graduate committee at OSU. During her dissertation research, AJ spent ten weeks in at the National Museum of Natural History as a graduate fellow in Botany during the summer of 2014. She was a Smithsonian Botany Peter Buck postdoctoral fellow in 2016-2018. She subsequently spent two years as a postdoctoral fellow at Oberlin College in 2018-2020. AJ accepted an associate professor position in South China Botanical Garden, in Guangzhou, China in 2020.

While AJ was working on the phylogenetics and biogeography of the buckeye genus Aesculus (Sapindaceae) at NCSU, she encountered issues related to inferring biogeography of the genus due to the uncertain phylogenetic relationships of the group. This is a common challenge faced by biogeographers. She came up with an algorithm to explore the impact of phylogenetic uncertainties on biogeographic inference by statistically sampling the many phylogenetic trees derived from a dataset of her study model Aesculus. She developed RAD@Y, a Python 2.5 user interface program that implemented her method published in Journal of Systematics and Evolution in 2009 (DOI: 10.1111/j.1759-6831.2009.00044.x). The method was later incorporated into the computer program S-DIVA (Statistical Dispersal-Vicariance Analysis), co-developed by AJ and her collaborators published in Molecular Phylogenetics and Evolution in 2010 (DOI: 10.1016/j.ympev.2010.04.011). She and her collaborators have subsequently developed another computer software RASP (Reconstruct Ancestral State in Phylogenies, DOI: 10.1016/j.ympev.2015.03.008) for inferring ancestral state using S-DIVA, Lagrange (DEC), Bayes-Lagrange (S-DEC), BayArea and BBM (Bayesian Binary MCMC) method. Both S-DIVA and RASP have been widely used by the biogeography research community, and the latter is a comprehensive software in biogeography and has gained more popularity in the last few years.

At the Smithsonian, AJ used highly integrative approaches to pursue studies on phylogenetic and biogeographic assembly on the Northern Hemisphere intercontinental disjunct plants. She tackled the phylogenetics and biogeography of the charismatic maple genus Acer and its close relatives, Dipteronia, Aesculus, and the neotropical Billia. She also conducted field work in the U.S. and Costa Rica during her fellowship. She provided analysis on the morphological and molecular variational patterns of Aesculus-Billia-Acer comparatively. Part of her work also incorporated ecological traits in the diversification and assembly of North American maples, especially on functional traits of fruits and leaves. Furthermore, AJ successfully utilized morphology, palynology, and paleontology in her systematic studies on Acer, Aesculus, and Staphyleaceae. 

AJ was very collaborative and worked well with colleagues in different academic stages. AJ had a fantastic presence at the Smithsonian, mentoring undergraduate interns and helpful to graduate students, postdocs, and visitors in the Department of Botany, especially when focused on phylogenetic, phylogenomic, and biogeographic analyses. 

During her time at the Smithsonian, AJ organized an important symposium on the assembly of the North American flora at the XIX International Botanical Congress held in Shenzhen, China in July 2017. The symposium was nicely done with 12 speakers exploring the advances of the topic from perspectives of phylogenetics, ecology, paleobotany, paleoclimates, biogeography, and bioinformatics. The set of papers was published as a special issue in Journal of Systematics and Evolution in September 2018 (DOI: 10.1111/jse.12459), with AJ as the lead editor of the special issue “Continents as Units for the Study of Floristic Assembly and Biodiversity: Focus on North America.” 

AJ was an active reviewer for many journals. She served as an editor for Ecology and Evolution for several years. She was an editorial board member for Journal of Systematics and Evolution from 2019-2023.

AJ was such a warm soul and was extremely helpful to numerous colleagues and friends nearly to the end of her life. Almost everyone is in disbelief that AJ is gone! She will be deeply missed by her friends and colleagues. AJ is survived by her husband Andrew Dabbs and her parents, Nancy and Joseph Harris.