Allozyme and microsatellite data reveal small clone size and high genetic diversity in aspen in the southern Cascade Mountains

• Published in: Forest ecology and management Vol. 258; no. 5; pp. 687 - 696
• Main Authors: De Woody, Jennifer, Rickman, Tom H., Jones, Bobette E., Hipkins, Valerie D.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 20-08-2009; [Amsterdam]: Elsevier Science; Elsevier
• Subjects: alleles; Americas; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Cascades; clones; forest trees; Forestry; Fundamental and applied biological sciences. Psychology; gene flow; gene frequency; Genet; genetic markers; genetic variation; Genetics; geographical variation; Isozymes; loci; microsatellite repeats; Microsatellites; Mountains; population genetics; Populus; Populus tremuloides; Reproduction; Somatic mutation; SSR; Stands; Stems; Supports; Synecology; Terrestrial ecosystems; Lassen National Forest; Cascade Mountain region; United States; North America; America; USA, Cascade Mts; USA, Utah, Intermountain West; Somatic mutation; SSR; Isozymes; Populus; Genet; Isozyme; Physical environment; Allozyme; Biodiversity; Cascade Range; Mountain; Dicotyledones; Angiospermae; Tree; Clone; Microsatellite; Vegetals; Small dimension; Enzyme; Biochemical compound; Forest ecology; Genetic diversity; Data; Woody plant; Salicaceae; Forestry; Spermatophyta; Mutation
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2009.05.006

The most widely distributed tree in North America, quaking aspen (Populus tremuloides, Michx.), reproduces sexually via seed and clonally via suckers. The size of aspen clones varies geographically, generally smaller in the east and large in the arid Intermountain West. In order to describe clone size and genetic structure of aspen in the southern Cascade Mountains, 864 stems from six sites were assayed at 15 isozyme and 6 microsatellite loci. Although isozymes reveal significantly lower levels of allelic richness (P<0.001) and expected heterozygosity (P<0.01), differences in genet diversity (isozyme G/N=0.45, microsatellite G/N=0.47) and allele frequency variation (isozyme FST=0.02, microsatellite FST=0.03) were nonsignificant. While a majority of stands were monoclonal, such stands were small, and the number of clones per stand was positively correlated with stand size (P<0.0001). High genetic diversity, low genetic differentiation, and a rapid decay of spatial genetic structure consistent with long distance gene flow during seedling recruitment indicate that sexual reproduction is a significant factor contributing to the genetic structure of these populations. These findings further resolve the geographic variation in clonal structure observed in aspen across North America, providing novel information for land management and conservation efforts.