Danny Nielsen and Dr. Loreen Allphin, Department of Plant and Wildlife Sciences
The rare endemic Lake Tahoe Draba (Draba asterophora) plant is under threat of extinction due to completed and proposed grating of ski runs on two ski resorts near Lake Tahoe where this species is located. This is of concern to both the US Forest Service and the two ski resorts, and they are cooperating to study this issue. In correspondence with the Forest Service, Dr. Allphin and I have conducted studies with this plant from three isolated clusters in order to determine the potential ecological consequences of this proposed grating, and whether or not certain subpopulations of the species can be eliminated while allowing the persistence of surrounding populations and moreover the preservation of the species as a whole. These three clusters are Mount Rose, Heavenly and Southwestern. The findings of this study have increased understanding of how rare isolated plant populations with restricted gene flow and high degrees of endemism respond to human disturbance.
During July 2007, I traveled to Lake Tahoe California/Nevada to collect specimens of Draba asterophora. Specimens were collected from two different ski resorts and other various locations around Lake Tahoe. These were prepared in vouchers and brought back to the lab to be analyzed using allozyme electrophoresis. Tissue samples were prepared in a phosphate grinding buffer and stored in an ultra low freezer to preserve the material. Allozyme electrophoresis was then used to analyze the genetic variability between subpopulations. Enzymes were surveyed for variable allozyme loci as seen in figure 1, using protocols described by Soltis et al. (1983), Odrzykoski and Gottlieb (1984), and Allphin and Windham (2002). These data were then analyzed statistically to determine several genetic indices including: observed heterozygosity, expected heterozygosity, average alleles per locus, etc.
The Mount Rose cluster is tetraploid, and shows no fixation of heterozygotes. The Heavenly cluster has yielded banding patterns indicative of the presence of diploid, tetraploid and mixed individuals. The Southwestern cluster contains unique alleles at the same loci. Our data illustrate that these populations each show significant genetic variation and multiple ploidy levels, which will provide important guidelines as a management plan is created for the Tahoe Draba.
While valuable results have been produced from our work we have had difficulties with some aspects. We have had difficulties in getting some of the enzyme systems to produce results which are adequate for analysis causing us to spend additional time altering various methods including: gel consistency, gel run time, and electrode buffers. Enzyme systems we have had best results with have been TPI, PGI and LAP; they have given us many of our allozyme loci.
However, the difficulties we have had have given me a better understanding of lab work. Similarly, they have provided me the opportunity to adjust lab protocol to produce desirable results which I feel is an important skill to have in the lab.
This project has been very helpful to me as I have gained valuable experience in field work as well as with various lab techniques. Also, as a result of doing this research, I will be presenting my findings at the Utah Conference of Undergraduate Research in February 20081 and possibly at the Botany scientific conference during summer 2008. Another possible outcome is a publication in which I will be one of the authors. Finally, these skills have aided me as I plan to pursue graduate studies after I complete my undergraduate degree.
Sources
- Allphin, L. and M. D. Windham. 2002. Morphological and genetic variation among populations of the rare Kachina daisy (Erigeron kachinensis) from Southeastern Utah. Western North America Naturalist 64 (4): 423-436.
- Odrzykoski and Gottlieb. 1984. Duplication of genes coding 6-Phophogluconate dehydrogenase in Clarkia (Onagraceae) and their phylogenetic implications. Systematic Botany 9: 479-489.
- Soltis, D. et al. 1983. Starch gel electrophoresis of ferns: a compilation of grinding buffers, gel and electrode buffers, and staining schedules. American Fern Journal 73: 9-27.