Annals of Botany 90: 219-230, 2002
© 2002 Annals of Botany Company
Floral and Vegetative Morphometrics of Five Pleurothallis (Orchidaceae) Species: Correlation with Taxonomy, Phylogeny, Genetic Variability and Pollination Systems
1 Departamento de Botânica, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, Campinas, São Paulo, 13083-970, Brazil, 2 Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana, Rodovia BR 116, km 03, Campus Universitário, Feira de Santana-BA, 44031-060, Brazil and 3 Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
* For correspondence. Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana. E-mail borba{at}uefs.br
Received: 18 April 2001; Returned for revision: 2 September 2001; Accepted: 18 April 2002
Morphometric analyses of vegetative and floral characters were conducted in 21 populations of five Pleurothallis (Orchidaceae) species occurring in Brazilian ‘campo rupestre’ vegetation. A phylogenetic analysis of this species group was also carried out using nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2). Results of the ordination and cluster analyses agree with species’ delimitation revealed by taxonomic and allozyme studies. The groups formed in ordination analysis correspond to the pollinator groups determined in a previous pollination study. Relationships among the species in the cluster analysis using only vegetative characters are similar to those found in a previous allozyme study, but those indicated by cluster analysis using only floral characters differ. These results support the hypothesis that floral similarities are due to convergence driven by similar pollination mechanisms, and therefore floral traits may not be good indicators of phylogenetic relationships in this group. The results of the phylogenetic analysis support this conclusion to some extent. There is no correlation between genetic (allozyme) and morphological variability in the populations nor in the way this variability is distributed among conspecific populations. We describe a new subspecies of Pleurothallis ochreata based on differences in vegetative and chemical characters as well as geographic distribution. Absence of differentiation in floral characters, attraction of the same pollinator species, interfertility and genetic similarity support the argument for subspecific rather than specific status.
Key words: Pleurothallis, Pleurothallis ochreata subsp. cylindrifolia, Orchidaceae, morphometrics, phylogeny, convergence, morphological variability, campo rupestre.
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