Cortaderia sp. in New Zealand: patterns of genetic variation in two widespread invasive species

Cortaderia selloana (pampas grass) and C. jubata (purple pampas grass) are both invasive in New Zealand. Cortaderia selloana is found throughout most of the country, whereas C. jubata is restricted to the North Island and the northern South Island. We examine the genetic variation present in each of the species, and compare this to the findings of an earlier study that analysed the variation in invasive C. jubata plants from New Zealand. Cortaderia selloana is comprised of two main genetic groupings in New Zealand, one of which is more common than the other. The distribution of these two genetic groupings is discussed with respect to introduction history. Cortaderia jubata has considerably more genetic variation than expected, higher than estimated by a previous work. We discuss these results in the context of Cortaderia invasion in New Zealand and how this may impact on the design of a biocontrol programme.