Phylogeny and evolution of Baptistonia (Orchidaceae, Oncidiinae) based on molecular analyses, morphology and floral oil evidences

Abstract : Baptistonia is endemic to the Brazilian Atlantic Forest and is made up of 23 species, the phylogenetic relationships of which are analysed here. Three plastid regions ( psbA-trnH , rpoB-trnC and trnS-G ) were sequenced. Using seven inter-simple sequence repeat (ISSR) markers, we scored 183 loci of ISSR dominant markers. Trees were obtained by successively using (a) maximum parsimony and Bayesian analysis of individual and combined sequence data sets, (b) neighbour joining (NJ) and Dollo parsimony of the ISSR data and (c) NJ analysis of the floral oil composition. These approaches, as well as the results of a previous morphological analysis, were combined using a supertree method, yielding clearer relationships within the genus. Various results of our study indicate that the Baptistonia species are recently radiated. B. colorata and B. venusta (previously known as Oncidium trulliferum ) are confirmed as being sister to the remaining species of the genus. Four taxonomic groups are clearly inferred. The evolution of some morphological traits and floral oil composition proved to be strongly linked to the phylogeny.