title: Invasion of Lepidium draba (Brassicaceae) in the western United States: distributions and origins of chloroplast DNA haplotypes.
abstract: Advances in phylogeography are of great value for understanding the population structure and origins of invasive genotypes. Such insights provide constructive information for current or future biological control research efforts. In this study, we investigated a highly variable chloroplast DNA (cpDNA) marker for populations of the weed Lepidium draba (Brassicaceae) in its native Eurasian and invasive US ranges. We sequenced DNA from 684 individuals from Eurasia and the US and found 41 different haplotypes. Our comparative study between the native and invasive ranges showed a 33% reduction in allelic richness (A) and a 7% reduction in haplotype diversity (h) since introduction into the US. Most genetic variation in the native range was observed within geographical regions and populations, not between regions, and this result was similar for the invasive range. Assignment tests indicated the most likely origins of many invasive haplotypes. Some of these occurred in western Europe, supporting an expanded native range that had been proposed for the species. Exact locations were identified for a diverse set of invasive haplotypes which can be used in ongoing host-specificity tests of potential biological control agents.
authors.affiliation: Northern Plains Agricultural Research Laboratory, USDA-ARS, P.O. Box 463, Sidney, MT 59270 USA. jgaskin@sidney.ars.usda.gov
authors.forename: John F
authors.initials: JF
authors.lastname: Gaskin
authors.forename: Dao-Yuan
authors.initials: DY
authors.lastname: Zhang
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Bon
mesh_terms: D000704:Analysis of Variance; D001483:Base Sequence; D001499:Bayes Theorem; D016000:Cluster Analysis; D017931:DNA Primers; D018742:DNA, Chloroplast / Q000235:genetics; D003710:Demography; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D029686:Lepidium / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D011157:Population Dynamics; D017422:Sequence Analysis, DNA; D014481:United States
chemical_list: D017931:DNA Primers; D018742:DNA, Chloroplast