Evolution in Apiales: nuclear and chloroplast markers together in (almost) perfect harmony

Relationships within the angiosperm order Apiales have long been difficult to interpret. Traditionally, the order comprised two families, Apiaceae and Araliaceae. Recent studies, however, suggest three additional lineages should also be recognized in the order (Pittosporaceae plus two tribes segregated from Araliaceae, Mackinlayeae and Myodocarpeae), and that one taxon (Apiaceae subfamily Hydrocotyloideae) is polyphyletic. Nuclear data also support the placement of five enigmatic genera (Aralidium, Griselinia, Melanophylla, Pennantia and Torricellia) within an expanded Apiales. To date, detailed molecular studies of Apiales have relied largely on data derived from plastid sequences, especially matK and rbcL. To test and complement the results of these studies, the 26S (large subunit) of nuclear ribosomal DNA was sequenced and analysed phylogenetically. Results from this study confirm that Apiales comprise five major lineages: core Apiaceae, core Araliaceae, Pittosporaceae, the Mackinlaya group and the Myodocarpus group. Moreover, using an expanded sampling of members of subfamily Hydrocotyloideae, the nature and extent of the polyphyly is confirmed, with members of this taxon found among four distinct clades within Apiales. (C) 2004 The Linnean Society of London.