Microsatellite DNA variation within and among invasive populations of Ambrosia artemisiifolia from the southern Pannonian Plain

Summary Although the P annonian P lain presents one of the areas in E urope most highly infested by A mbrosia artemisiifolia, previously reported population genetic studies of the invasive species have included only a few populations from this region. Our goal was to determine the level of genetic diversity and genetic structure of A . artemisiifolia populations from the southern P annonian P lain using microsatellite DNA markers. We documented a high level of genetic diversity within the P annonian populations, as compared with the genetic diversity parameters previously published for the other invasive populations of A . artemisiifolia in E urope. The mean number of alleles per locus ( N A ) ranged between 6.8 and 9.4, allelic richness ( r ) between 6.59 and 8.53 and mean number of rare alleles per locus ( N R ) ranged between 3.4 and 6.4 per analysed population. A low level of among‐population differentiation was detected, with percentage of variation between populations of 3.3%, generally low pairwise F ST values (ranged from −0.007 to 0.152) and also according to principal coordinate analysis. A B ayesian approach revealed that most individuals did not strongly associate with any single genetic cluster, confirming a lack of genetic structuring in the analysed region. Together with the results of quantification of the level of gene flow ( N m  = 5.671), these observations indicated a presence of extensive gene exchange and admixture between the populations. Therefore, A . artemisiifolia in the P annonian P lain region has the potential for rapid expansion.