PHYLOGENETIC-RELATIONSHIPS OF THE BROMELIIFLORAE-COMMELINIFLORAE-ZINGIBERIFLORAE COMPLEX OF MONOCOTS BASED ON RBCL SEQUENCE COMPARISONS

Four cladistic hypotheses were constructed for Dahlgren's Bromeliiflor ae-Commeliniflorae-Zingiberiflorae complex, primarily from suggestions of affinities according to morphology-based treatments: (i) Dahlgren' s treatment of the families is correct; (ii) the Bromeliaceae and Zing iberales are sister groups; (iii) the complex is monophyletic, with th e Arecaceae as the closest outgroup; and (iv) a clade that contains th e Bromeliaceae and Commelinaceae is monophyletic. These four hypothese s were evaluated using sequence data from the chloroplast gene, rbcL, that codes for the large subunit of ribulose-1,5-bisphosphate carboxyl ase/oxygenase. Results were compared between a broad analysis of 499 r bcL sequences and a smaller data set that included only families of th e complex plus the Arecaceae (52 taxa). The larger data analysis suppo rted hypothesis (iii), minus the Velloziaceae. However, hypotheses (i) and (ii) were not supported, and support for hypothesis (iv) was equi vocal. Three decisions on classification can be made based on the resu lts of this study: (i) submerge the Bromeliiflorae into the Commelinif lorae; (ii) remove the Velloziaceae from the complex; and (iii) remove the Cyclanthaceae and Pandanaceae from the Areciflorae.