EVOLUTIONARY RELATIONSHIPS IN RUBUS (ROSACEAE) BASED ON MOLECULAR DATA

Rubus is economically and ecologically important, displays a high degree of morphological diversity, and is one of the most taxonomically challenging genera of flowering plants. Polyploidy, agamospermy, and hybridization complicate species circumscription and infrageneric classification. As a foundation for an efficient breeding program, pest and pathogen management, and studies of systematics and biogeography, a robust estimate of phylogenetic relationships must be established. I sequenced the nuclear ribosomal DNA internal transcribed spacer (ITS) region for 64 Rubus species representing all 12 subgenera, Dalibarda repens, and three outgroups. Parsimony analysis of the ITS region data set indicates the following results. Rubus plus Dalibarda form a strongly supported monophyletic group, although the status of Dalibarda as a separate genus remains unclear. Of the recognized subgenera with more than one sampled species, only subg. Orobatus appears monophyletic, suggesting the need for a complete taxonomic revision. Nevertheless, several clades are strongly supported. One includes all members of nine of the 12 subgenera. Morphologically this group is characterized primarily by armed woody stems and compound leaves. Raspberries (subg. Idaeobatus) are clearly polyphyletic and blackberries (subg. Rubus) can be considered monophyletic with modification. Polyploid Rubus ursinus appears to be of hybrid origin with a blackberry species serving as its maternal parent and the Hawaiian endemic R. macraei or a close relative as its paternal parent.