title: Low genetic diversity but strong population structure reflects multiple introductions of western flower thrips (Thysanoptera: Thripidae) into China followed by human-mediated spread.
abstract: Historical invasion scenarios based on observational records are usually incomplete and biased, but these can be supplemented by population genetic data. The western flower thrips (WFT),Frankliniella occidentalis, invaded China in the last 13 years and has rapidly become one of the most serious pests in the country. To assess whether this invasion involved a single event or multiple events, we examined patterns of genetic diversity and population structure of WFT across 12 Chinese populations and a native US population based on mitochondrial DNA and/or 18 microsatellite loci. The average allelic richness and haplotype diversity in Chinese populations were significantly lower than in a population from its native range. The distribution of mitochondrial haplotypes suggested multiple independent invasions of WFT into China, including two invasions into the Beijing region. Based on microsatellite data, two distinct clusters were identified, with both of them splitting further into two clusters; in the Beijing region, the microsatellite data also provided evidence for two introductions. Both the absence of isolation by distance and the fact that distant populations were similar genetically suggest patterns of WFT movement linked to human activities. Our study therefore suggests multiple introductions of WFT into China and human-assisted spread.
authors.affiliation: Institute of Plant and Environmental Protection Beijing Academy of Agriculture and Forestry Sciences Beijing China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Cao
authors.affiliation: Institute of Plant and Environmental Protection Beijing Academy of Agriculture and Forestry Sciences Beijing China.
authors.forename: Ze-Hua
authors.initials: ZH
authors.lastname: Wang
authors.affiliation: Institute of Plant and Environmental Protection Beijing Academy of Agriculture and Forestry Sciences Beijing China.
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Gong
authors.affiliation: Institute of Plant and Environmental Protection Beijing Academy of Agriculture and Forestry Sciences Beijing China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhu
authors.affiliation: School of BioSciences Bio21 Institute The University of Melbourne Melbourne Vic. Australia.
authors.forename: Ary Anthony
authors.initials: AA
authors.lastname: Hoffmann
authors.affiliation: Institute of Plant and Environmental Protection Beijing Academy of Agriculture and Forestry Sciences Beijing China.
authors.forename: Shu-Jun
authors.identifier: 0000-0001-7398-0968
authors.initials: SJ
authors.lastname: Wei
keywords: Frankliniella occidentalis; invasive species; microsatellite; mitochondrial gene; multiple introductions; population genetics