Abstract Detail

Population Genetics/Genomics

Lopez, Alexander Joseph [1], Shrestha, Anil [2], Sosnoskie, Lynn [3], Waselkov, Katherine [1].

Origins of Amaranthus tuberculatus (Waterhemp) in Central Valley Agroecosystems: A Population Genetics Approach Using Genotyping-By-Sequencing.

Native to the Mississippi valley, Amaranthus tuberculatus (waterhemp) has quickly become one of the most troublesome and aggressive weeds throughout the Midwestern United States since first invading agroecosystems in the 1950s. Despite the species being largely absent from California’s agriculturally intensive Central Valley, waterhemp is now being increasingly observed invading agroecosystems within Merced County in the last decade. The aim of this study is to (1) map the distribution of these waterhemp infestations in the Central Valley, (2) genetically characterize and determine the geographic origin(s) of this invasion, and (3) evaluate evolutionary routes that may have facilitated this invasion. In 2019, we identified seven (7) large waterhemp infestations invading various agricultural cropping systems within Merced County between Highways 140 & 152 (almond, corn, hay, rice). Genetic clustering analyses with potential source populations across the species’ native range detected two genetic units in the Midwest consistent with the geographic ranges of the two previously reported varietal forms of the species. Merced infestations showed significant admixture in two populations but altogether clustered closest with the western rudis variety, recognized as the predominant driver of invasiveness in the species. Further analysis of the history of this invasion indicated it was likely facilitated through multiple introduction events from admixed populations in the native range. Together, these results suggest that Merced waterhemp infestations are likely preadapted for invasion success in agricultural fields in California’s Central Valley and thus effective management will be critical. Future work will explore whether the existing adaptations of this new waterhemp range expansion include herbicide resistance, which is very common in the Midwestern native range and critical to its success in agroecosystems.

1 - California State University Fresno, Biology, 2555 East San Ramon Ave M/S SB73, Fresno, Ca, 93740, USA
2 - California State University Fresno, Viticulture & Enology, 2415 East San Ramon Ave M/S AS72, Fresno, Ca, 93740, USA
3 - Cornell University, School of Integrative Plant Science, 635 W North St., 221 Hedrick Hall, Geneva, NY, 14456, USA

none specified

Presentation Type: Oral Paper
Number: PGG1005
Abstract ID:209
Candidate for Awards:None

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