Nuclear and chloroplast microsatellites show multiple introductions in the worldwide invasion history of common ragweed, Ambrosia artemisiifolia

• Published in: PloS one 2011-03, Vol.6 (3), p.e17658-e17658
• Main Authors: Gaudeul, Myriam, Giraud, Tatiana, Kiss, Levente, Shykoff, Jacqui A
• Format: Article
• Language: English
• Subjects: Adaptation; Ambrosia - genetics; Ambrosia artemisiifolia; Bayes Theorem; Biodiversity; Biology; Cell Nucleus - genetics; Centaurea diffusa; Chloroplasts; Chloroplasts - genetics; Cluster Analysis; Colonization; Dispersal; DNA, Chloroplast - genetics; Evolution & development; Expansion; Genetic diversity; Genetic Loci - genetics; Genetic markers; Genetic structure; Genetic Variation; Genetics, Population; Geography; Haplotypes - genetics; Heracleum; History; Inbreeding; Internationality; Introduced Species; Invasive plants; Life Sciences; Microsatellite Repeats - genetics; Microsatellites; Nonnative species; Population; Population Dynamics; Population genetics; Population sampling; Population studies; Populations; Populations and Evolution; Principal Component Analysis; Range extension; Seeds; Studies; Success
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0017658

Ambrosia artemisiifolia is a North American native that has become one of the most problematic invasive plants in Europe and Asia. We studied its worldwide population genetic structure, using both nuclear and chloroplast microsatellite markers and an unprecedented large population sampling. Our goals were (i) to identify the sources of the invasive populations; (ii) to assess whether all invasive populations were founded by multiple introductions, as previously found in France; (iii) to examine how the introductions have affected the amount and structure of genetic variation in Europe; (iv) to document how the colonization of Europe proceeded; (v) to check whether populations exhibit significant heterozygote deficiencies, as previously observed. We found evidence for multiple introductions of A. artemisiifolia, within regions but also within populations in most parts of its invasive range, leading to high levels of diversity. In Europe, introductions probably stem from two different regions of the native area: populations established in Central Europe appear to have originated from eastern North America, and Eastern European populations from more western North America. This may result from differential commercial exchanges between these geographic regions. Our results indicate that the expansion in Europe mostly occurred through long-distance dispersal, explaining the absence of isolation by distance and the weak influence of geography on the genetic structure in this area in contrast to the native range. Last, we detected significant heterozygote deficiencies in most populations. This may be explained by partial selfing, biparental inbreeding and/or a Wahlund effect and further investigation is warranted. This insight into the sources and pathways of common ragweed expansion may help to better understand its invasion success and provides baseline data for future studies on the evolutionary processes involved during range expansion in novel environments.