Riser Ii, James P. , Roalson, Eric H. .
Gene flow, species boundaries, and phylogeography of the dwarf milkweed group (Asclepias uncialis-ruthiae-eastwoodiana-sanjuanensis, Asclepiadoideae: Apocynaceae).
The dwarf milkweed group comprises four diminutive species of early flowering milkweeds (Asclepias uncialis, A. ruthiae, A. eastwoodiana, and A. sanjuanensis) native to xeric habitats of western North America. Three of the four species are considered rare or sensitive by various land management agencies. All four species have populations characterized by small groups of stems (or even single individuals) widely scattered across (seemingly) suitable habitat. Genetic diversity within groups of stems is unknown, but may be very low due to the clonal growth common in milkweeds, i.e., a particular group of stems may actually only represent a single genetic individual. The amount and nature of gene flow between these widely distributed groups is unknown. Three of the four species have been treated as infraspecific taxa of Asclepias uncialis; however, significant morphological differences exists between the putative species and their distributions are essentially allopatric in all but one case. As with the intra-specific population genetic structure, the amount of inter-specific gene flow between these four taxa is also unknown. Here we apply a combination of molecular approaches to address the amount and distribution of genetic variation within and among populations, how genetically distinct the currently recognized species are from each other, and how the lineages of the dwarf milkweeds are related to each other.
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1 - Washington State University, School of Biological Sciences, Pullman, WA, 99164-4236, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 556A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:00 AM