Submitted in fulfillment of a 2012 Nantucket Biodiversity Initiative grant.
Centaurea maculosa (Spotted Knapweed) and Centaurea jacea (Brown Knapweed) are members of the Composite family (Asteraceae) and natives of Eurasia. C. maculosa is a major invasive species in North America, dominating large stretches of grassland. Both species were introduced on Nantucket island, and aim of this study is to describe genetic structure and diversity of these weeds. Analyses based on chloroplast DNA sequence data suggest just one introduction of these species on Nantucket island. The only outlier appears to be a specimen H5, and based on its morphology it was suggested that we found a specimen of Centaurea nigrescens on Nantucket island that has not been described there before. The further analysis of nuclear DNA with microsatellite markers might elucidate a potential gene flow and hybridization between these two species as all hybrid-like plant specimen clustered together with C. jacea cpDNA sequences, suggesting environmental plasticity of brown knapweed and not a genetic diversity.
Centaurea maculosa (Spotted Knapweed) and Centaurea jacea (Brown Knapweed) are members of the Composite family (Asteraceae) and natives of Eurasia. C. maculosa is a major invasive species in North America, dominating large stretches of grassland. Both species were introduced on Nantucket island, and aim of this study is to describe genetic structure and diversity of these weeds. Analyses based on chloroplast DNA sequence data suggest just one introduction of these species on Nantucket island. The only outlier appears to be a specimen H5, and based on its morphology it was suggested that we found a specimen of Centaurea nigrescens on Nantucket island that has not been described there before. The further analysis of nuclear DNA with microsatellite markers might elucidate a potential gene flow and hybridization between these two species as all hybrid-like plant specimen clustered together with C. jacea cpDNA sequences, suggesting environmental plasticity of brown knapweed and not a genetic diversity.