Molecular systematics and character evolution in Caryophyllaceae

The aim of the present study was to infer a substantially larger, more evenly sampled, phylogenetic tree for Caryophyllaceae in order to more confidently resolve relationships within this clade. This would allow us to evaluate previous classification schemes and to infer the evolution of a number of characters that have figured prominently in higher-level taxonomic treatments. We have inferred a 630-tip phylogeny (ca. 30% of the 2200 species) using maximum likelihood analyses of data from the nuclear ribosomal ITS region and five chloroplast genes and intergenic spacers: matK, ndhF, trnL-trnF, trnQ-rps16, and trnS-trnfM. Our results confirm that subfamily Paronychioideae is paraphyletic at the base of Caryophyllaceae. Alsinoideae and Caryophylloideae together form a clade, within which neither subfamily is monophyletic. With only a few exceptions, our results support the tribal classification presented by Harbaugh & al. (2010). In agreement with other recent studies, it appears that many of the larger genera are not strictly monophyletic. Our results imply that the first Caryophyllaceae had stipules, free sepals, small apetalous flowers with few stamens, and single-seeded indehiscent or irregularly dehiscing utricles. Stipules were lost along the branch to the Alsinoideae-Caryophylloideae clade, and the evolution of a tubular calyx marks Caryophylloideae. The evolution of petals, 10 stamens, and capsule fruits is inferred to have taken place along the branch subtending a clade that includes Sperguleae (mostly containing former members of Paronychioideae) and the remainder of Caryophyllaceae. As this previously unnamed major group is both well-supported in molecular phylogenetic studies and marked by clear-cut apomorphies, we propose the name Plurcaryophyllaceae for this clade and provide a phylogenetic definition.