Molecular phylogeny of Caryophyllidae s.l. based on MatK sequences with special emphasis on carnivorous taxa

Despite intensive morphological, chemical and cladistic studies on Caryophy llidae, the circumscription of this subclass acid the interfamilial relatio nships are still under discussion. Using comparative sequencing of the chlo roplast matK gene, hypotheses of relationships between the carnivorous Dros eraceae, Nepenthaceae and Dioncophyllaceae and ten other families of the Ca ryophyllidae s.l. were tested and compared with previously published cladog rams based on rbcL, 18S rDNA and ORF2280 sequences. Parsimony analyses indi cate two well-differentiated clades. One strongly supported clade comprises the carnivorous families Droseraceae and Nepenthaceae. along with its clos e relatives Dioncophyllaceae and Ancistrocladaceae. The second clade is res tricted to the Polygonaceae, Plumbaginaceae, Tamaricaceae and Frankeniaceae . The Simmondsiaceae are more closely related to Caryophyllales and are at the base of the remaining taxa. Results of this analysis suggest that carni vory within Caryophyllidae s.l. has a monophyletic origin and, with the exc eption of Triphyophyllum, this syndrome was lost in the taxa of Dioncophyll aceae and Ancistrocladaceae. The exclusion of Drosophyllum from Droseraceae suggests no close relationship with this family. Finally, the data support a sister group relationship between the Plumbaginaceae and Polygonaceae an d the Frankeniaceae and Tamaricaceae. An extensive survey of the rpl2 intro n via PCR amplification indicates that the intron is absent from chloroplas t genomes of Droseraceae and all taxa of Caryophyllales, but is present in Drosophyllum. Consequently, there is evidence for a multiple loss of the in tron and strong support that Drosophyllum has affinities outside the Droser aceae. Our sequence data corroborate many aspects of recent cladistic analy ses based predominantly on rbcL sequences. This study shows that matK seque nces are useful for phylogenetic inference among closely related members of Caryophyllidae.