Molecular evolution and variability of ITS1–ITS2 in populations of Deschampsia antarctica from two regions of the maritime Antarctic

Only two vascular plants, Deschampsia antarctica Desv. (Poaceae) and Colobanthus quitensis Kunth. Bartl. (Caryophyllaceae), inhabit the Antarctic. To clarify the taxonomic position, phylogeographic origin, genetic heterogeneity, and population dynamics of D. antarctica, we comparatively analyzed the ITS1 and ITS2 sequences for several populations from two geographically distant regions of the maritime Antarctic (the South Shetland Islands and the Argentine archipelago). All accessions of D. antarctica formed a strongly supported clade in the phylogenetic dendrograms constructed. Despite the high degree of sequence similarity at ITS1–ITS2 (97%–100%), the populations of D. antarctica in Tierra del Fuego, Falkland Islands and Antarctic can be discriminated at the molecular level. Our data indicate that the majority of D. antarctica populations originated from South America. Different populations may have invaded Antarctic at different times. Genetically distinct plants may coexist within the same or adjacent populations on Antarctic islands.