Phylogenetic relationships and evolution of Crassulaceae inferred from matK sequence data

Chloroplast gene matK sequence data were used to estimate the phylogeny of 112 species of Crassulaceae sampled from 33 genera and all six recognized s ubfamilies. Our analyses suggest that Eve of six subfamilies recognized in the mast recent comprehensive classification of the family are not monophyl etic. Instead, we recovered a basal split in Crassulaceae between the south ern African Crassula clade (Crassuloideae) and the rest of the family (Sedo ideae). These results are compatible with recent studies of cpDNA restricti on site analyses. Within Sedoideae, four subclades were also recovered: Kal anchoe, Leucosedum, Acre, and Aeonium; evidence also exists for a Telephium clade and Sempervivum clade. The genus Sedum is highly polyphyletic with r epresentatives spread throughout the large Sedoideae clade. Sympetaly and p olymerous flowers have arisen multiple times in Crassulaceae and thus are n ot appropriate characters upon which to base subfamilial limits, as has bee n done in the past. One floral character haplostemy, appears to be confined to the well-supported Crassula clade. Our analyses suggest a southern Afri can origin of the family, with subsequent dispersal northward into the Medi terranean region. From there, the family spread to Asia/eastern Europe and northern Europe; two separate lineages of European Crassulaceae subsequentl y dispersed to North America and underwent substantial diversification. Our analyses also suggest that the original base chromosome number in Crassula ceae is x = 8 and that polyploidy has played an important role in seven cla des. Three of these clades are exclusively polyploid (Sempervivum clade and two subclades within the Kalanchoe and Aeonium clades), whereas four (Cras sula, Telephium, Leucosedum, and Acre clades) comprise both diploid and pol yploid taxa. Polyploidy is particularly rampant and cytological evolution e specially complex in the Acre clade.