Chloroplast DNA restriction site phylogeny of the genus Androcymbium (Colchicaceae)

We examined phylogenetic relationships among 51 populations representing 18 of the approximately 40 currently recognized species in the genus Androcym bium using 559 parsimony informative cpDNA restriction site changes. Our re sults indicate that the genus is monophyletic and had a southern African or igin. According to our estimates of divergence times, species distributed i n North Africa arose in the early Miocene from an ancestor related to A. eu conoides. The two Canary Island endemics originated from an ancestor relate d to the North African A. wyssianum in the early Pliocene. Strong support f or the monophyly of all the species represented by more than one population casts doubt on the inclusion of the six North African species into a Andro cymbium gramineum complex and provides strong evidence against the possibil ity of reticulation in these species. Lack of support for the monophyly of the two currently recognized sections (Androcymbium and Erythrostictus) sug gests that the presence of wing-like appendages on the tepals is not a reli able taxonomic character for sectional circumscription. Molecular clock est imates emphasize the importance of ecological diversity in the differentiat ion of South African species. In sharp contrast, the much less pronounced p attern of change among north African species seems to have been fostered by their relatively recent origin and by the uniform ecological conditions th at prevail in their areas of geographic distribution.