Abstract
The Eastern Cape is regarded as the centre of diversity for Passerina, except for two species occurring in the outliers of eastern Africa. Ten species are endemic to the Cape Floristic Region and four are regarded as near endemics. A complete species-level phylogeny for Passerina utilising sequences from three plastid and one nuclear gene is presented. The loci sequences were rbcL, trnL-F, rps16 and ITS. Parsimony and Bayesian analysis yield identical relationships and two informal groupings are described. Passerina is well imbedded within the tribe Gnideae and not sister to it as previously suggested. The elevation of the subtribe Passerininae (under the tribe Gnidieae) to the monogeneric tribe Passerineae, is thus not supported. The age of the root node of Passerina was estimated to evaluate the widely held view that much of the diversification in the Cape occurred ca. 5Mya with the start of the Mediterranean climate. Contrary to this, the timing and the temporary dynamics of the radiation of Passerina indicated that the lineage is at least 18 million years old and that the diversification rate had declined slightly over the past 5 million years. In Passerina, it also appears that speciation has been largely allopatric with a high frequency of range shifts.
Dr. M. van der Bank