Phylogenetic Relationships in Tribe Cariceae (Cyperaceae) Based on Nested Analyses of Four Molecular Data Sets

Abstract

Phylogenelic reconstruction for Carex and relatives in tribe Cariceae is complicated by species richness and nearly cosmopolitan distribution. In this investigation, our main objective was to estimate evolutionary relationships in tribe Cariceae using DNA sequence data from two spacer regions in nuclear ribosomal genes (ITS and ETS-lf) combined with noncoding chloroplast DNA (trnL intron, tnrL-trnF intergenic spacer, and trnE-trnD intergenic spacers). Parsimony analyses of separate and combined data and Bayesian analysis of the combined data matrix revealed strong support for monophyly of tribe Cariceae and for monophyly of two major lineages, one comprising principally Carex subgen. Carex and Vigneastra, and the other representing subgen. Vignea. A third clade with representatives from Kabresia and Uncinia, along with Cymophyllus fraserianus, Carex curvula, and several unispicate Carex received weak-to-moderate support. A small clade comprising Schoenoxiphium and two unispicate carices was placed as sister to the clades comprising multispicate Carex species in the parsimony analysis, but sister to the clade of Kobresia, Uncinia, and unispicate Carex in the Bayesian analysis. Two large widespread groups within suhgen. Carex, sect. Hymenochlaenae and sect. Physocarpae S.I. ("bladder sedges"), were highly polyphyletic, while ten clades that grouped species from two or more sections were each strongly supported as monophyletic. Within suhgen. Vignea, three sections were strongly supported as monophyletic while sects. Phaestoglochin and Vulpinae were polyphyletic. Adding the variable ETS-1f region improved resolution and bootstrap support values over previous studies, but many of the characters supporting major branches came from the trnL region.