Genetic Diversity and Structure of on the Kaibab Plateau: Implications for Conservation.

Assessing patterns of genetic diversity within and among closely related congeners is important for evaluating the conservation status of rare plant taxa. We used nuclear microsatellite genotyping to examine the genetic relatedness among three taxa on the Kaibab Plateau in northern Arizona. Over 100 species of are recognized, and are widely distributed in Western North America. On the Kaibab Plateau several taxa occur, including and two subspecies of subsp. and subsp. . The latter subspecies, the Kaibab bladderpod, is rare and endemic to the Kaibab Plateau and is a potential candidate to be listed under the Endangered Species Act. Morphological characters, primarily flower color, have been used to distinguish subsp. from other subspecies. Here we aim to assess its genetic diversity and differentiation as compared to congeners on and around the Kaibab Plateau. We genotyped DNA obtained from leaf samples from 463 individuals collected from 26 sites representing the three putative taxa (12 subsp. , 8 subsp. , and 6 ). Our results showed that all samples initially identified as subsp. and subsp. on the Kaibab Plateau form a single genetic cluster that is well-differentiated from subsp. sampled from sites off the plateau or on or off the plateau. For on the plateau, our findings do not support the previous subspecies designations based on morphological characters. While additional studies of will further resolve taxonomic uncertainties within this species, our findings indicate that the Kaibab Plateau population is genetically diverse and genetically distinct, and federal protection is justified in light of the threats faced on the Kaibab Plateau and its limited range.