Phylogeny of some species of Cyrtandra (Cesneriaceae) inferred from the atpB/rbcL cpDNA intergene region

The PCR-amplified atpB/rbcL spacer region of ten Cyrtandra species and representatives of the genera Didymocarpus, Didissandra, and Monophyllaea was sequenced and used for phylogenetic analyses. In Cyrtandra 83 variable positions were found over a length of 890bp. The data suggest that the Samoan species included in our study originated by at least two independent colonization events, while for the Hawaiian species the situation is not clear yet. With respect to generic relationships, Monophyllaea shows considerable divergence (9.9%) from the remaining taxa and thus is used as outgroup. Didymocarpus is most closely related to Cyrtandra, their genetic divergence (2.2%) being only slightly higher than the average distance within Cyrtandra (1.9%). The promoter regions for the atpB and rbcL genes, which have been described from Rubiaceae, were identified and found to be located at homologous positions. Of the two atpB promoters found in Rubiaceae only the distal one appears functional, the proximal promoter has been eroded by mutations and is disrupted in Didissandra by a 14bp insertion.