746 Journal of Heredity, 2019, 746–759 doi:10.1093/jhered/esz047 Original Article Advance Access publication July 29, 2019 © The American Genetic Association 2019. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com Original Article Genetic Diversity and Population Structure of Wild Sunfower (Helianthus annuus L.) in Argentina: Reconstructing Its Invasion History Fernando Hernández , Alejandro Presotto, Mónica Poverene, and Jennifer R. Mandel From the Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina (Hernández, Presotto, and Poverene); the Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS), CONICET-Bahía Blanca, 8000 Bahía Blanca, Argentina (Hernández, Presotto, and Poverene); and the Department of Biological Sciences, University of Memphis, Memphis, TN 38152 (Mandel). Address correspondence to Fernando Hernández, Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina, or e-mail: fhernandez@cerzos-conicet.gob.ar . Received March 20, 2019; First decision April 26, 2019; Accepted July 27, 2019. Corresponding Editor: Mark Chapman Abstract Studying the levels and patterns of genetic diversity of invasive populations is important to understand the evolutionary and ecological factors promoting invasions and for better designing preventive and control strategies. Wild sunfower (Helianthus annuus L.) is native to North America and was introduced, and has become invasive, in several countries, including Argentina (ARG). Here, using classical population genetic analyses and approximate Bayesian computation (ABC) modeling, we studied the invasion history of wild sunfower in ARG. We analyzed 115 individuals belonging to 15 populations from ARG (invasive range) and United States (US, native range) at 14 nuclear and 3 chloroplast simple sequence repeat markers along with 23 phenotypic variables. Populations from ARG showed similar levels of nuclear genetic diversity to US populations and higher genetic diversity in the chloroplast genome, indicating no severe genetic bottlenecks during the invasion process. Bayesian clustering analysis, based on nuclear markers, suggests the presence of 3 genetic clusters, all present in both US and ARG. Discriminant analysis of principal components (DAPC) detected an overall low population structure between central US and ARG populations but separated 2 invasive populations from the rest. ABC modeling supports multiple introductions but also a southward dispersal within ARG. Genetic and phenotypic data support the central US as a source of introduction while the source of secondary introductions could not be resolved. Finally, using genetic markers from the chloroplast genome, we found lower population structure in ARG when compared with US populations, suggesting a role for seed-mediated gene fow in Argentina. Keywords: approximate Bayesian computation, chloroplast SSR, discriminant analysis of principal components, invasive sun- flower Downloaded from https://academic.oup.com/jhered/article/110/6/746/5540155 by guest on 15 June 2022