Genetic diversity and population structure of invasive and native populations of Erigeron canadensis L.

Abstract Invasive alien plants threaten biodiversity across the world. Erigeron canadensis (horseweed) is one of the most problematic agricultural weeds and represents a classic example of intercontinental invasion. Here, we studied the genetic diversity and population structure of invasive alien populations from the Jiangsu and Zhejiang Provinces in China and native populations from Alabama, in the USA. We used 10 polymorphic SSR loci to genotype 312 individuals from 5 native and 5 invasive populations to estimate the genetic diversity and structure. Invasive populations from Jiangsu and Zhejiang Provinces showed, on average, similar genetic diversity to native populations from Alabama, indicating no severe genetic bottlenecks during the invasion. STRUCTURE revealed that low population differentiation occurred, and that only two genetic groupings were detected in both native and invaded ranges. The high diversity observed in the invasive populations suggested multiple introductions and/or the introduction of genetically diverse propagules during initial colonization. Our study provides new insights toward understanding the invasion dynamics of this globally noxious weed in Eastern China. Preventing gene flow via seed dispersal between invasive and native populations should be examined to prevent the introduction and dispersal of herbicide-resistant individuals and inform management practices.