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Abstract Detail


Systematics Section

Alexander, Jason Andrew [1], Liston, Aaron [2].

The genetic distinctiveness of Astragalus lentiginosus var. maricopae and A. lentiginosus var. ursinus (Fabaceae)- two restricted endemics in the southwestern United States.

Astragalus lentiginosus of Section Diphysi is one of the most diverse species in Fabaceae. The Palantia, a name first used by Rydberg, are taxa with cylindrical pods that, unlike the other 40 varieties of A. lentiginosus, do not become bladdery inflated. Astragalus lentiginosus var. mokiacensis and A. lentiginosus var. palans are the most widespread and morphologically diverse taxa in this group. The two most restricted taxa, A. lentiginosus var. ursinus (endemic to limestone talus in Mohave County, Arizona and Washington County, Utah) and A. lentiginosus var. maricopae (endemic to granitic alluvium in northeastern Maricopa County, Arizona) are the only highly restricted endemics in the Palantia. Both are disjunct from their more widespread relatives. Population genetic analyses of chloroplast microsatellite loci were used to determine the levels and distribution of genetic diversity among populations of these taxa. Astragalus lentiginosus var. maricopae and A. lentiginosus var. ursinus were found to have levels of genetic diversity higher than their widespread relatives. However, both were only highly genetically differentiated from A. lentiginosus var. mokiacensis, the taxon with the highest morphological similarity to these two endemics. Neither of the endemics exhibit the low genetic diversity and high chloroplast differentiation found in many other peripheral, disjunct taxa. One likely explanation for this pattern is that A. lentiginosus var. maricopae and A. lentiginosus var. ursinus are relictual populations of a taxon that gave rise to the more widespread taxa.


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1 - Utah Valley University, Biology Department, Utah Valley University Herbarium, 800 West University Parkway, Orem, Utah, 84058, USA
2 - Oregon State University, Department of Botany & Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA

Keywords:
Astragalus
Fabaceae
cp-microsatellites
principal coordinates analysis
Utah
Arizona.

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 3
Location: Maybird/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 10:30 AM
Number: 3010
Abstract ID:302


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