Geographic patterns of genetic variation and population structure in Pinus aristata, Rocky Mountain bristlecone pine
Pinus aristata Engelm., Rocky Mountain bristlecone pine, has a narrow core geographic and elevational distribution, occurs in disjunct populations, and is threatened by rapid climate change,
white pine blister rust, and bark beetles. Knowledge of genetic diversity and population structure will help guide gene conservation strategies for this species. Sixteen sites across four mountain ranges in the core distribution of P. aristata were sampled and genetic diversity was
assessed with 21 isozyme loci. Low species and population level genetic diversity (H
e = 0.070 and 0.062, respectively) occurred with moderate among-population differentiation (F
ST = 0.131). Genetic diversity correlated with longitude, latitude,
and elevation and a strong mountain island effect may contribute to substructuring and isolation. Using multiple complementary analyses, sampled trees were assigned to three genetic lineages that varied in diversity and admixture and were associated with different climatic factors. The distribution
of genetic diversity and substructuring of P. aristata may be an outcome of a combination of restricted gene flow due to geographic and phenological isolation, random processes of genetic drift, life history traits, natural selection, and postglacial migrations. The combination of low
genetic diversity, moderate population isolation, and a protracted regeneration dynamic puts populations at risk for extirpation by novel stresses.
Document Type: Research Article
USDA Forest Service, Rocky Mountain Research Station, 240 West Prospect Road, Fort Collins, CO 80526, USA.
USDA Forest Service, National Forest Gel Electrophoresis Laboratory, 2480 Carson Road, Placerville, CA 95667, USA.
USDA Agricultural Research Services, National Center for Genetic Resources Preservation, 1111 S. Mason Street, Fort Collins, CO 80523, USA.
Publication date: 2012-01-30
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