title: Towards resolving Lamiales relationships: insights from rapidly evolving chloroplast sequences.
abstract: BACKGROUND
  In the large angiosperm order Lamiales, a diverse array of highly specialized life strategies such as carnivory, parasitism, epiphytism, and desiccation tolerance occur, and some lineages possess drastically accelerated DNA substitutional rates or miniaturized genomes. However, understanding the evolution of these phenomena in the order, and clarifying borders of and relationships among lamialean families, has been hindered by largely unresolved trees in the past.
  
  
  RESULTS
  Our analysis of the rapidly evolving trnK/matK, trnL-F and rps16 chloroplast regions enabled us to infer more precise phylogenetic hypotheses for the Lamiales. Relationships among the nine first-branching families in the Lamiales tree are now resolved with very strong support. Subsequent to Plocospermataceae, a clade consisting of Carlemanniaceae plus Oleaceae branches, followed by Tetrachondraceae and a newly inferred clade composed of Gesneriaceae plus Calceolariaceae, which is also supported by morphological characters. Plantaginaceae (incl. Gratioleae) and Scrophulariaceae are well separated in the backbone grade; Lamiaceae and Verbenaceae appear in distant clades, while the recently described Linderniaceae are confirmed to be monophyletic and in an isolated position.
  
  
  CONCLUSIONS
  Confidence about deep nodes of the Lamiales tree is an important step towards understanding the evolutionary diversification of a major clade of flowering plants. The degree of resolution obtained here now provides a first opportunity to discuss the evolution of morphological and biochemical traits in Lamiales. The multiple independent evolution of the carnivorous syndrome, once in Lentibulariaceae and a second time in Byblidaceae, is strongly supported by all analyses and topological tests. The evolution of selected morphological characters such as flower symmetry is discussed. The addition of further sequence data from introns and spacers holds promise to eventually obtain a fully resolved plastid tree of Lamiales.
authors.affiliation: Institute for Evolution and Biodiversity, University of Muenster, Hüfferstraße 1, 48149 Münster, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Schäferhoff
authors.forename: Andreas
authors.initials: A
authors.lastname: Fleischmann
authors.forename: Eberhard
authors.initials: E
authors.lastname: Fischer
authors.forename: Dirk C
authors.initials: DC
authors.lastname: Albach
authors.forename: Thomas
authors.initials: T
authors.lastname: Borsch
authors.forename: Günther
authors.initials: G
authors.lastname: Heubl
authors.forename: Kai F
authors.initials: KF
authors.lastname: Müller
mesh_terms: D002736:Chloroplasts / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D019684:Magnoliopsida / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny
chemical_list: D018744:DNA, Plant