The movement of plants for use in agriculture has had a significant impact on the population structure of many species and resulted in the introduction of a significant number of invasive species. To evaluate the impact agricultural use can have on the invasion history of a species, the population structure of reed canarygrass (Phalaris arundinacea) in Eurasia and across its invasive range in North America was evaluated. Reed canarygrass is one of the worst wetland invaders in North America, but has been planted as a forage crop and for soil stabilization for at least the past century in North America. The geographic origin of invasive populations in North America has remained a mystery. Fifteen simple sequence repeat (SSR) markers were used to determine the geographic origin and population structure of invasive populations in North America using an extensive collection of 110 Eurasian accessions, 40 early herbarium specimens from North America, and 231 present-day North American collections.
Results/Conclusions
While native North American populations of reed canarygrass are still present in North America, only three of the 231 North American accessions sampled were confirmed to be of North American origin. All other North American populations were descendants of Eurasian populations. All Eurasian subpopulations were present in North America and invading populations in North America were as diverse as populations in the Eurasian range, suggesting there has been no genetic bottleneck during the migration of Eurasian populations to North America. Based on these results, we conclude that Eurasian populations are more aggressive in North American wetlands than native North American populations and that neither breeding, nor hybridization among distinct populations is responsible for the development of invasive traits. We hypothesize that Eurasian populations are more productive and have a superior response to nutrient inputs than native North American populations.