ALEXANDER, J. ANDREW* and AARON LISTON. Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331. - Tests of recombinant speciation in Astragalus.
Astragalus mokiacensis Gray (Fabaceae), and Astragalus
preussii Gray var. laxifolorus Gray are taxa endemic to the
Mojave Desert that may be hybrids between two different sections of
this genus. A. mokiacensis is endemic to northeastern Clark
County, Nevada and northwestern Mohave County, Arizona. A.
preussii var. laxiflorus is endemic to the Lake Mead region
of eastern Clark County, Nevada. These species are sympatric around
Lake Mead, however, A. preussii var. laxiflorus is
restricted to gypsum soils and A. mokiacensis can be found on a
variety of soil types. Two prevalent theories exist on the taxonomic
relationships of A. mokiacensis and A. preussii var.
laxiflorus: either they are related to one of several varieties
of A. lentiginosus (Section Diphysi) or they are related
to A. preussii var. preussii (Section
Preussiani). Alternatively, they could be recombinant hybrids
between the two species. The relationships between A.
mokiacensis, A. preussii var. laxiflorus, A.
preussii var. preussii, A. lentiginosus var.
ambiguus, A. lentiginosus var. palans, A.
lentiginosus var. yuccanus will be investigated based on
analyses of the internal transcribed spacer region (ITS) and
Key words: Astragalus mokiacensis, Astragalus preussii var. laxiflorus, ITS, Mojave Desert, Nevada, recombinant speciation