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Systematics Section / ASPT

Salgado Hernández, Esmeralda [1], González Ledesma, Manuel [1], Gernandt, David S. [1].

The phylogenetic position of Astragalus (Fabaceae) species from central Mexico.

Astragalus, with approximately 2500 to 3000 species, is the largest genus of flowering plants.The genus is distributed throughout cold and arid regions worldwide. New World species (Neo-Astragalus) are prodominantly aneuploids (n = 11-15) and Old World species are euploids and polyploids (n = 8, 16, 32).This division is supported by phylogenies based on both nuclear ITS region and chloroplast sequences but not by morphological characters.Most species in the genus have yet to be included in a molecular study.We sequenced the ITS region of nuclear ribosomal DNA for five of the twelve species of Astragalus recognized from the central valley of Mexico, (comprising parts of the Distrito Federal, and the states of Mexico, Hidalgo, Tlaxcala, Puebla, and Morelos).Cladistic analysis of an alignment that included previously published sequences together with sequences of these five species (A. guatemalensis var. lozani, A. oxirrynchus, A. mollissimus var. irolanus, A. strigulosus, and A. hypoleucus) indicated that the Mexican species are members of Neo-Astragalus, and that all species sampled except A. mollisimus form a subclade together with species from South America (A. patagonicus, A. palanae, and A. neuquenensis) and with two species from Arizona (A. arizonicus and A. nothoxys). Several reproductive and vegetative morphological characters were mapped onto the ITS region tree to identify possible synapomorphies for the group.


1 - Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Biologicas, AP 1-69, Plaza Juarez, Pachuca, Hidalgo, 42001, Mexico

Keywords:
Astragalus
nrDNA ITS
Neo-Astragalus
phylogeny.

Presentation Type: Poster
Session: 32-100
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:729


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