Genetic reconstruction of potential invasion pathways of Ligustrum lucidum into Argentina

Abstract

The study of the genetic characteristics of invasive plant species in native and invaded ranges is an increasingly important attempt for understanding current patterns of invasive plants distribution. While Argentina holds a significant number of invasive woody plant species, scant research has been conducted to determine their invasion pathways. Here we aimed to reconstruct the invasion pathways of Glossy privet (Ligustrum lucidum W.T. Aiton, Oleaceae) from its native range in China to Argentina using nuclear and chloroplastidial molecular markers (ITS1-5.8S-ITS2 and rpl16). Because invasion processes imply an initial founder effect in the new range, we expect to find higher haplotype diversity in native populations. Also, we hypothesize that the invasion route from China to Argentina was through Europe due to the human migratory pathways of the late XIXth century. We sampled 9 locations in the native Chinese range (N = 30), and 15 locations from invaded ranges in Argentina, Mexico and Spain (N = 45). We observed higher haplotype diversity across the three invaded ranges studied here, where we also found two nDNA haplotypes that were not present in the native range examined. The haplotype network revealed that all haplotypes found in Argentina are shared with Spain and Mexico. While the sharing of haplotypes in the three invaded ranges hints towards a single source of introduction, the number of different haplotypes in the invaded ranges in such a short time period suggests multiple introductions. Based on our genetic results and on first records of L. lucidum in Europe (Spain, Italy, UK) and México, we discuss potential invasion routes into Argentina considering historical human commerce and migratory patterns.