There is debate over the native or exotic status of Myriophyllum spicatum L. (Haloragaceae) in South Africa, which has important implications for developing and implementing management strategies. The aim of this study was to determine if M. spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear ribosomal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations. For both these DNA markers, the South African populations were distinct from Eurasian populations, but always stemmed from a European origin. The data suggest that South African and European M. spicatum share a common ancestor, however the divergence of both markers are characteristic of a long period of isolation rather than a recent introduction from Europe. The genetic data from this study suggest that M. spicatum has not been introduced recently, but is most likely a native component of the South African flora.
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Many thanks to the local and international colleagues who assisted this study by collecting genetic material from all over the globe: Antoine Gander, Carla Lambertini, Dean Impson, Iain Gunn, Kristina Steffen, Lesley Henderson, Patrick Grillas, Rene Sforza, Roger Monge, Rosemary Mangan, Sangkyu Park, Seonah Jeong, Shahzada Arshid, Steve Compton, Tenna Riis, Xinwei Xu. Without them, this study would not have been possible. Assistance with collection of molecular data was provided by Christopher Anderson, Meghan Jeffers, Nayell Palomino, Jeffrey Pashnick, Andrew Pyman, and Dustin Wcisel. The Working for Water Programme of the Natural Resource Management Programmes (Department of Environmental Affairs), South Africa and University of Minnesota CFANS faculty development award are thanked for their financial support of this project.
- Genetic analysis
- Geographic isolation