Abstract Detail

Rupert Barneby and his legume legacy

Alexander, J. Andrew [1], Liston, Aaron [1].

Astragalus mokiacensis Gray and the Astragalus lentiginosus Douglas ex Hook. complex (Fabaceae): Is the scarcely-inflated pod a result of multiple independent parallelisms?.

Due to its diversity, the Astragalus lentiginosus complex in western North America has had a unique taxonomic history. According to the most current revision, Astragalus lentiginosus, a polymorphic species that comprises over 40 varieties, ranges from British Columbia to Mexico and California to Colorado. Over half of these varieties are endemic to the Intermountain States of Utah, Nevada and Arizona. In contrast, Astragalus mokiacensis is an endemic to the Virgin and the Colorado River drainages in Clark County, Nevada and Mohave County, Arizona.
The varieties of Astragalus lentiginosus are polymorphic in features that are fixed in other North American species of Astragalus, primarily the presence of bilocular or semibilocular pods, inflated or scarcely inflated pods, and deciduous or persistent pods. The ill-defined nature of Astragalus mokiacensis and putatively related varieties of Astragalus lentiginosus with scarcely inflated pods has led to difficulty delimiting these taxa. In examining the treatments by 20th century taxonomists, one can discern two hypotheses of relationship between these taxa: either they are a monophyletic group arising and differentiating into separate, minutely different varieties; or they are a polyphyletic assemblage in which the scarcely inflated, semibilocular pod has arisen from multiple, independent lineages. Essentially, is the scarcely inflated pod a result of a single radiation event or a result of multiple independent parallelisms?
Amplified fragment length polymorphism (AFLP) markers have a high potential to yield multiple, polymorphic markers that could assist in determining the levels and patterns of genetic differentiation among varieties of Astragalus lentiginosus. Preliminary molecular and morphometric analyses provide clues to the relationships of Astragalus mokaicensis to the other members of this complex. Ultimately, testing Barneby's phylogenetic hypotheses with molecular and morphologic methods may provide insight into the evolution of Astragalus in North America.

1 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA

Keywords:
AFLP
Astragalus
Fabaceae
endemic
Arizona
Utah
Nevada
morphometrics.

Presentation Type: Symposium
Session: 19-11
Location: Magpie (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 4:45 PM
Abstract ID:591