Phylogenetic relationships of Deschampsia antarctica (Poaceae): Insights from nuclear ribosomal ITS

Deschampsia antarctica E. Desv. is the only monocot in the Antarctic floristic zone. We evaluated the phylogenetic relationships of Deschampsia antarctica to other grasses using parsimony as the optimality criterion. Five different sets of gap, transversion and transitions costs were explored to analyze the effect of parameter choice on the phylogenetic results. Both internal transcribed spacers (ITS1 and ITS2) and the 5.8S subunit of nuclear ribosomal DNA were included in the analysis. A total of 43 species were analyzed including seven species of Deschampsia. Deschampsia antarctica forms a well supported group with five species of Deschampsia. Deschampsia does not appear monophyletic as D. flexuosa (L.) Trin. is not included in this clade. The clade to which D. antarctica belongs is sister to some Aveneae in all analyses. This study is the first contribution that evaluates the phylogenetic position of D. antarctica in relation to other species of Deschampsia.