Journal Article

A phylogenetic study of Laeliinae (Orchidaceae) based on combined nuclear and plastid DNA sequences

Cássio van den Berg, Wesley E. Higgins, Robert L. Dressler, W. Mark Whitten, Miguel A. Soto-Arenas and Mark W. Chase

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 104, issue 3, pages 417-430
Published in print August 2009 | ISSN: 0305-7364
Published online May 2009 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcp101
A phylogenetic study of Laeliinae (Orchidaceae) based on combined nuclear and plastid DNA sequences

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Laeliinae are a neotropical orchid subtribe with approx. 1500 species in 50 genera. In this study, an attempt is made to assess generic alliances based on molecular phylogenetic analysis of DNA sequence data.

Methods

Six DNA datasets were gathered: plastid trnL intron, trnL-F spacer, matK gene and trnK introns upstream and dowstream from matK and nuclear ITS rDNA. Data were analysed with maximum parsimony (MP) and Bayesian analysis with mixed models (BA).

Key Results

Although relationships between Laeliinae and outgroups are well supported, within the subtribe sequence variation is low considering the broad taxonomic range covered. Localized incongruence between the ITS and plastid trees was found. A combined tree followed the ITS trees more closely, but the levels of support obtained with MP were low. The Bayesian analysis recovered more well-supported nodes. The trees from combined MP and BA allowed eight generic alliances to be recognized within Laeliinae, all of which show trends in morphological characters but lack unambiguous synapomorphies.

Conclusions

By using combined plastid and nuclear DNA data in conjunction with mixed-models Bayesian inference, it is possible to delimit smaller groups within Laeliinae and discuss general patterns of pollination and hybridization compatibility. Furthermore, these small groups can now be used for further detailed studies to explain morphological evolution and diversification patterns within the subtribe.

Keywords: Laeliinae; Orchidaceae; ITS; trnL intron; trnL-F spacer; matK

Journal Article.  8503 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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