A REVIEW OF MOLECULAR PHYLOGENETIC STUDIES OF RUBIACEAE

Rubiaceae is one of the five largest families of flowering plants with over 13,000 species. We have seen a tremendous increase in our understanding of the phylogeny of the family through studies on molecular data during the 15-year period from 1991 to 2005; some new relationships are completely unexpected and different from traditional classification. At the end of 2005, ca. 50 phylogenetic reconstructions from the family had been published based on more than 4400 sequences. Most studies are based oil ITS and rbcL sequences, but 13 different markers have been used. Most sequences available in GenBank (as of 2005) are from rps 16, trn(T)L-F, rbcL, and ITS. We call now see a framework of the family phylogeny with support for three subfamilies and over 43 tribes; subfamily Cinchonoideae (Chiococceae, Cinchoneae, Guettardeae, Hamelieae, Hillieae, Hymenodictyeae, Isertieae, Naucleeae, Rondeletieae), subfamily Ixoroideae (Alberteae, Bertiereae, Coffeeae, Condamineeae, Cremasporeae, Gardenieae, Ixoreae, Mussaendeae, Octotropideae, Pavetteae, Posoquerieae, Retiniphylleae, Sabiceeae, Sipaneeae, Vanguerieae), and subfamily Rubioideae (Anthospermeae, Argostemmateae, Coussareeae, Craterispermeae, Danaideae, Gaertnereae, Knoxieae, Lasiantheae, Morindeae, Ophiorrhizeae, Paederieae, Psychotrieae, Putorieae, Rubieae, Schradereae, Spermacoceae, Theligoneae. Urophylleae), and tribe Coptosapelteae, which is placed outside the three subfamilies. Two of these tribes, Gardenieae and Morindeae, are paraphyletic/polyphyletic. Only about half of the tribes have been the focus Of specific investigations. However, we have seen increased interest in using Rubiaceae phylogenies for studies of ecology, evolution, and biogeography, e.g., and also for morphological and anatomical investigations. Evolution of fruit traits, flower types, and myrmecophytism has been investigated, and biogeographic patterns for specific taxa in Africa, the Caribbean, and the Pacific have been studied. In addition, distribution of pollen types, chemical substances, and wood characteristics have been compared with molecular phylogenies.