Record Details
Population and conservation genetic structure of the Cascades frog, Rana cascadae throughout the species' range
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Population and conservation genetic structure of the Cascades frog, Rana cascadae throughout the species' range |
| Names |
Monsen, Kirsten J.
(creator) Blouin, Michael S. (advisor) |
| Date Issued | 2002-10-25 (iso8601) |
| Note | Graduation date: 2003 |
| Abstract | A major goal of conservation biology is to elucidate the population genetic structure in threatened species and assess the relative importance of the evolutionary forces that shape that population genetic structure. I conducted three studies in the declining amphibian Rana cascadae to assess levels of population genetic differentiation and the relative importance of gene flow versus random genetic drift throughout the species' range. In the first study, 1 examined phylogeographic structure on a species-wide geographic scale with both mitochondrial and nuclear molecular markers. I found three mitochondrial groups within R. cascadae that are as divergent at the mitochondrial DNA as sister species. However, I only found two nuclear groups within R. cascadae, suggesting there are two Distinct Population Segments and three Management Units within the species' range. In the second study, I compared sequence data from mtDNA and nuclear DNA of the three R. cascadae mtl)NA groups to several closely related Pacific Northwestern ranid species. I found the surprising result that the mtDNA of R. aurora aurora is more closely related to the mtDNA of' R. cascadae than to the mtDNA of its own subspecies R. aurora drayloni. The nuclear data support the sub-specific relationship between R. aurora aurora and R. aurora draytoni. This result is most likely due to incomplete lineage sorting of ancestral mtDNA alleles. Finally, in the third study, I examined the relative importance of gene flow versus random genetic drift on a fine geographic scale using microsatellite loci. Additionally, I estimated the long-term effective population sizes and genetic neighborhood size for 11 R. cascadae populations. Rana cascadae shows extreme isolation by distance with very little gene flow occurring past a distance of 10 km. Long-term effective population sizes were unrealistically large for current effective population sizes, but the estimates oF genetic neighborhood size are consistent with those expected based on current census population size and genetic neighborhood size in other amphibians. My research suggests Rana cascadae should be managed as three separate groups corresponding to the Olympic Peninsula, the Cascades of Washington and Oregon, and Northern California. Additionally, R. cascadae exhibits extreme isolation by distance with reduced gene flow at distances greater than 10 km, suggesting metapopulation structure is weak, and populations that go extinct are unlikely to be re-colonized quickly despite the presence of nearby R. cascadae populations. |
| Genre | Thesis/Dissertation |
| Topic | Rana -- Geographical distribution |
| Identifier | http://hdl.handle.net/1957/19341 |
