Investigating the population biology of an invasive plant species, Phragmites australis, in its native and non-native ranges

This thesis examines the genetic and ecological components of an invasive plant, P. australis (haplotype M), in both its native and non-native ranges. The first objective of this study was to identify whether stands of P. australis occupy a wide range of habitats in its native range, Great Britain, as a result of local adaptations or as a result of broad environmental tolerances. The second objective of this study was to explore within and between population structure using molecular data and to make inferences on life history traits utilized by invasive stands of P. australis in North America. Analyses support the conclusion that in Great Britain P. australis has broad environmental tolerances and can respond in a plastic manner to at least some key environmental variables. In North America the analyses highlight two important life history traits previously poorly understand; reproduction and dispersal. These data provide insights into processes that may have facilitated the invasion of P. australis into North America and may prove useful in the conservation of P. australis in Great Britain where reedbeds are in decline.;Keywords: Invasive species, population genetics, Phragmites australis , life history traits, sexual reproduction, seed dispersal.