Visger, Clayton , Datwyler, Shannon .
A cytogeographical survey of California Penstemon section Saccanthera subsection heterophylli.
With approximately 275 species Penstemon represents one of the largest genera of plants endemic to North America. The mechanisms by which new species form in Penstemon are diverse, with specialization for different pollinators as one important mechanism. However, many species have undergone speciation without changes in pollinators. This study investigates a case of polyploid speciation within a small subgenus of the section Saccanthera, subsection heterophylii. While polyploidy is uncommon in the genus as a whole, Penstemon subsection heterophylli has been previously documented to include diploid (2X), tetraploid (4X), hexaploid (6X) and octoploid (8X) species. Furthermore, Penstemon heterophyllus has been documented to have both diploid and tetraploid cytotypes. However range differences between the two were not documented. This study utilized flow cytometry to evaluate the range and ploidy level of five to ten individuals from each of 12 P. heterophyllus populations as well as five to ten individuals from 18 populations representing five additional species that include 2X, 4X, 6X and 8X species. Populations of P. heterophyllus were found to include just one cytotype (either 2X or 4X). Tetraploid populations were found to be limited to the northern part of the geographic range. Further sampling during spring 2012 is needed to confirm that all northern populations are 4X. Additionally, a weak correlation was found between the ploidy level of Penstemon within this complex and elevation from which specimens were collected. (r2=0.472 p<0.001). Current work is focused on the use of microsatellites to evaluate single vs multiple origins of the tetraploid P. heterophyllus cytotype.
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1 - California State University Sacramento, Biology, 6000 J street, sacramento, ca, 95819-6077, USA
2 - California State University Sacramento, 6000 J Street, Sacramento, CA, 95819-6077, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 10:30 AM