Invasion genetics of Senecio vulgaris: loss of genetic diversity characterizes the invasion of a selfing annual, despite multiple introductions
Genetic variation in invasive populations is affected by a variety of processes including stochastic forces, multiple introductions, population dynamics and mating system. Here, we compare genetic diversity between native and invasive populations of the selfing, annual plant Senecio vulgaris to infer the relative importance of genetic bottlenecks, multiple introductions, post-introduction genetic drift and gene flow to genetic diversity in invasive populations. We scored multilocus genotypes at eight microsatellite loci from nine native European and 19 Chinese introduced populations and compared heterozygosity and number of alleles between continents. We inferred possible source populations for introduced populations by performing assignment analyses and evaluated the relative contributions of gene flow and genetic drift to genetic diversity based on correlations of pairwise genetic and geographic distance. Genetic diversity within Chinese populations was significantly reduced compared to European populations indicating genetic bottlenecks accompanying invasion. Assignment tests provided support for multiple introductions with populations from Central China and southwestern China descended from genotypes matching those from Switzerland and the UK, respectively. Genetic differentiation among populations in China and Europe was not correlated with geographic distance. However, European populations exhibited less variation in the relation between G ST and geographical distance than populations in China. These results suggest that gene flow probably plays a more significant role in structuring genetic diversity in native populations, whereas genetic drift appears to predominate in introduced populations. High rates of selfing in Chinese populations may restrict opportunities for pollen-mediated gene flow. Repeated colonization-extinction cycles associated with ongoing invasion is likely to maintain low genetic diversity in Chinese populations.
KeywordsGene flow Genetic diversity Genetic drift Multiple introductions Selfing
We thank Yong-Ming Yuan, Chen Xia, Dun-Yan Tan, and Quan-Guo Zhang for sampling and help with molecular analyses. Our work was supported by the National Natural Science Foundation of China (31421063), the 111 Project (B13008), the open project of the State Key Laboratory of Earth Surface Processes and Resource Ecology, and Fundamental Research Funds for Central Universities. A Discovery Grant from the Natural Sciences and Engineering Research Council of Canada supported the contribution of Spencer C.H. Barrett to this research.
- Barrett SCH (2011) Why reproductive systems matter for the invasion biology of plants. In: Richardson DM (ed) Fifty years of invasion ecology: the legacy of Charles Elton. Oxford University Press, Oxford, pp 195–210Google Scholar
- Barrett SCH, Husband BC (1990) Genetics of plant migration and colonization. In: Brown AHD, Clegg MT, Kahler AL, Weir BS (eds) Plant population genetics, breeding and genetic resources. Sinauer Associates, Massachusetts, pp 254–277Google Scholar
- Barrett SCH, Colautti RI, Dlugosch KM, Rieseberg LH (forthcoming) Invasion genetics: the Baker and Stebbings legacy. Wiley-Blackwell, OxfordGoogle Scholar
- Ferrero V, Barrett SCH, Castro S, Caldeirinha P, Navarro L, Loureiro J, Rodriguez-Echeverria S (2015) Invasion genetics of the Bermuda buttercup (Oxalis pes-caprae): complex intercontinental patterns of genetic diversity, polyploidy and heterostyly characterize both native and introduced populations. Mol Ecol 24:2143–2155. doi: 10.1111/mec.13056 CrossRefPubMedGoogle Scholar
- Frantzen J, Rossi F, Müller-Schärer H (2002) Integration of biological control of common groundsel (Senecio vulgaris) and chemical control. Weed Sci 50:787–793. doi: 10.1614/0043-1745(2002)050[0787:IOBCOC]2.0.CO;2
- Gillespie JH (2004) Population genetics: a concise guide, 2nd edn. Jonhs Hopkins Universtiy Press, BaltimoreGoogle Scholar
- Grace BS, Müller-Schärer H (2003) Biological control of Senecio vulgaris in carrots (Daucus carota) with the rust fungus Puccinia lagenophorae. Basic Appl Ecol 4:375–384. doi: 10.1078/1439-1791-00171
- Mitich LW (1995) Common groundsel (Senecio vulgaris). Weed Technol 9:209–211Google Scholar
- Novak SJ, Mack RN (2005) Genetic bottlenecks in alien plant species: influences of mating systems and introduction dynamics. In: Sax DF, Stachowicz JJ, Gaines SD (eds) Species invasions: Insights into ecology, evolution, and biogeography. Sinauer Associates, Sunderland, pp 201–228Google Scholar
- Steinger T, Haldimann P, Leiss KA, Muller-Scharer H (2002) Does natural selection promote population divergence? A comparative analysis of population structure using amplified fragment length polymorphism markers and quantitative traits. Mol Ecol 11:2583–2590. doi: 10.1046/j.1365-294X.2002.01653.x CrossRefPubMedGoogle Scholar
- R Core Team (2015) R: a language and environment for statistical computing. http://www.R-project.org/
- Xu HG, Qiang S (2004) Inventory invasive alien species in China. China Environmental Science Press, BeijingGoogle Scholar