Abstract

In the Western United States, the Great Basin is a geographic feature that is home to a variety of unique species, including Great Basin bristlecone pine (Pinus longaeva, PILO). P. longaeva is well known for the age of some of the trees, some of which are over 4000 years old. In this study 17 microsatellite markers (simple sequence repeat, SSR) are identified and used to genotype a selection of 480 individuals spread across 24 PILO populations and 60 individuals divided equally between 2 outgroup species, Pinus aristata and Pinus flexilis. One population of PILO, HMW, shows more genetic similarity with P. aristata, and is included with outgroup species in the analysis. The population structure of PILO is examined and found to be weakly related to the geographic distance between populations. The population statistics Fst, Gst, Rst, Dest and an AMOVA analysis suggest that there is a substantial amount of admixture at the individual level, similar to some other species of pines. Phylogenetic trees computed using the neighbor-joining method based on the average population genetic distance and based on individual genetic distance support the population structure results and show further evidence that most of the species variation is concentrated at the individual level, rather than inside of or between species. It is possible that gene flow is still occurring, or that gene flow has occurred recently enough that the separated populations have not yet diverged from each other in a measurable way.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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