Phylogeny and Biogeography of Endemic Festuca (Poaceae) from New Zealand Based on Nuclear (ITS) and Chloroplast (trnL–trnF) Nucleotide Sequences

Abstract

We investigated the phylogenetic relationships of the endemic New Zealand (NZ) species of Festuca (Poaceae, Pooideae) by assessing sequence variation from the nuclear internal transcribed spacers (ITS) and a chloroplast intergenic spacer (trnL-trnF) and by measuring DNA content using flow cytometry. The ITS and trnL-trnF data sets were congruent in showing that the NZ species of Festuca have two origins. One group, containing F. coxii, F. luciarum, F. multinodis, and F. ultramafica, is closely related to Festuca sect. Aulaxyper. The other group includes a clade of five endemic species (F. actae, F. deflexa, F. madida, F. matthewsii, F. novae-zelandiae) and one species (F. contracta) with a circumAntarctic distribution. The North American species F. californica is sister to the latter group in the trnL-trnF phylogeny but not so in the ITS phylogeny. The differentiation of endemic NZ species into two groups is supported by differences in chromosome number and genome size, the latter showing an inverse relationship to ploidy level. We discuss the ecology and biogeography of NZ's endemic species of Festuca. Origin from Northern Hemisphere ancestors via dispersal to NZ through the American continents is a plausible hypothesis based on current information.