Morphometrics and molecular phylogenetics of the continental African species of Angraecum section Pectinaria (Orchidaceae)

Simo-Droissart, Murielle, Micheneau, Claire, Sonké, Bonaventure, Droissart, Vincent, Plunkett, Gregory M., Lowry, Porter P., Hardy, Olivier J., and Stévart, Tariq (2013) Morphometrics and molecular phylogenetics of the continental African species of Angraecum section Pectinaria (Orchidaceae). Plant Ecology and Evolution, 146 (3). pp. 295-309.

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Abstract

Background and aims: Recent molecular studies suggest the polyphyly of Angraecum and the unnaturalness of some of its sections, as exemplified by sect. Pectinaria, which has species in two well-separated clades, one in Madagascar and the other in continental Africa. However, species delimitation among the five continental African members remained problematic due to morphological variability. In preparation for the taxonomic revision of this group, we used morphological and molecular data to re-assess the circumscription of each species, and to evaluate their monophyly and relationships to one another.

Methods: A total of 59 alcohol-preserved specimens were used to perform multivariate analyses on 37 morphological characters. DNA sequences from one nuclear (ITS-1) and five plastid regions (matK, rps16, trnL – F, trnC – petN and ycf1) were analyzed using Parsimony and Bayesian methods.

Key results: The morphometric study revealed five distinct morphospecies that correspond to the concepts of the currently recognized species. Angraecum doratophyllum and A. subulatum are the most distinct morphologically, whereas A. atlanticum, A. gabonense and A. pungens are most similar to one another. Phylogenetic analyses using a combined data set of the six markers yielded highly resolved, congruent trees with strong branch support. The polyphyly of A. sect. Pectinaria is confirmed, with continental African members appearing to be most closely related to sect. Dolabrifolia, found exclusively in Africa. The multiple accessions of A. doratophyllum, A. gabonense, A. pungens and A. subulatum each formed a well-supported clade. Parsimony and Bayesian analyses placed A. atlanticum and A. pungens in a subclade within which samples of A. pungens were nested but those of A. atlanticum formed a grade. These two species can be easily distinguished morphologically by leaf dimensions and flower length, but broader sampling in continental Africa is needed to test whether individuals recognized as A. atlanticum might represent two distinct taxa.

Item ID: 30544
Item Type: Article (Research - C1)
ISSN: 2032-3921
Keywords: angraecoid orchid, Angraecum, Bayesian analyses, continental Africa, molecular phylogeny, monophyly, morphometric analyses, parsimony, sect. Pectinaria
Funders: American Orchid Society, Central Africa Regional Program for the Environment (CARPE), “Sud Expert Plantes” project (#375), French Ministry of Foreign Affairs, DIVEAC, ECOFAC, U.S. National Science Foundation
Projects and Grants: U.S. National Science Foundation (1051547)
Date Deposited: 11 Dec 2013 05:26
FoR Codes: 06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060309 Phylogeny and Comparative Analysis @ 40%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060310 Plant Systematics and Taxonomy @ 50%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060409 Molecular Evolution @ 10%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960803 Documentation of Undescribed Flora and Fauna @ 20%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960805 Flora, Fauna and Biodiversity at Regional or Larger Scales @ 20%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 60%
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