PHYLOGENETIC IMPLICATIONS OF RBCL AND ITS SEQUENCE VARIATION IN THE BERBERIDACEAE

In spite of the use of chromosome number, floral anatomy, pollen morph ology, and serology, substantial disagreement remains regarding the sy stematics of the Berberidaceae. To test competing hypotheses about int ergeneric relationships in the family, sequences of the chloroplast en coded rbcL gene and TTS regions of the nuclear ribosomal repeat were e xamined. Analysis of rbcL sequences does not support fragmentation of the Berberidaceae into smaller families, especially the separation of Nandina as a distinct family. The large woody genera, Berberis and Mah onia, are related to the monotypic herbaceous genus Ranzania. Bongardi a is nested within a clade characterized by a basic chromosome number of x = 6, and has a remote relationship to the Leontice group with whi ch the genus has been placed in most previous classifications. The x = 6 group, the largest in the Berberidaceae, comprises two distinct lin eages: Jeffersonia and the rest of the core genera (Diphylleia, Bongar dia, Achlys, and Epimedium). Among the core genera, Diphylleia is sist er to Epimedium/Achlys and their sister genus Bongardia. ITS sequence data provided additional support for the phylogenetic relationships of the x = 6 group observed in the rbcL gene tree.