Systematics/Phytogeography / Taxonomie/ Section
Sanchez, Adriana , Kron, Kathleen A. .
Preliminary phylogenetic relationships of Calligonum L. (Polygonaceae) using two chloroplast genes.
Within Polygonaceae there are several genera that remain cryptic and poorly known. Such is the case of Calligonum, a genus comprising anywhere between 35 to 80 species (depending on the revision) and distributed in deserts of Asia, Africa and Southeastern Europe. Most of the species segregation is based on fruit characters. Their habit is shrubby and they possess morphological characters that are usually cryptic with leaves and other organs absent or very small. This makes them difficult taxonomically and therefore their phylogenetic relationships to other Polygonaceae are not known. Taxa such as these are rarely included in phylogenetic analyses yet are important components of regions of the world currently undergoing rapid rates of environmental change and thus are threatened with possible extinction. In this study we included seven representatives of Calligonum and other poorly known taxa such as Pteropyrum, which is distributed in southwestern Asia (five species have been described) and monotypic Pteroxygonum that occurs in China. For these taxa and other related Polygonaceae, we explored relationships using rbcL and matK. The matrix comprises 2090 bp and the number of parsimony informative characters is 31%. Results of parsimony analyses strongly support a monophyletic Polygonoideae, even though the relationships within this group are not well resolved. A clade comprising Calligonum, Pteropyrum and Pteroxygonum receives moderate-high support. This indicates that Calligonum is not monophyletic since Pteropyrum and Pteroxygonum are embedded with it. The results do not support previous classifications in which Pteroxygonum giraldii was considered a species within Fagopyrum.
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1 - Wake Forest University, Department of Biology, PO Box 7325, 226 Winston Hall, Winston-Salem, North Carolina, 27109-7325, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Room 1/Woodward
Date: Monday, July 28th, 2008
Time: 8:30 AM