Date of Award

Fall 1990

Project Type

Dissertation

Program or Major

Genetics

Degree Name

Doctor of Philosophy

First Advisor

Robert T Eckert

Abstract

The genetic structure of a two hectare stand of eastern white pine (Pinus strobus L.) was studied by relating foliar allozyme composition of individual trees to tree location and age. Using starch gel electrophoresis, the trees were found to have variants for six of the seven enzymes analyzed. Trees of similar age and with common allozymes were found in clusters, suggesting that genetic structure existed in the stand. The genetic structure may have originated during establishment of several seedlings from common parents when openings were created in the canopy. Knowing that a genetic structure, such as that observed in this study, may exist in "natural" forests is important to foresters who are concerned with maintaining current levels of genetic variability in those forests.

Evaluation of sampling strategies revealed that at least 50 randomly sampled trees would be required to correctly estimate allele frequencies, the number of alleles per locus, and heterozygosity in this stand. Smaller samples were likely to yield incorrect estimates by chance. To estimate polymorphism, between 100 and 250 trees would be needed. Reliable detection of deviations from allelic frequencies expected under the Hardy-Weinberg equilibrium required 25 to 425 randomly chosen trees, depending on allozyme frequencies for the enzyme in question. Differences in estimates for larger samples compared to smaller ones were due mainly to detection of additional low frequency alleles in the larger samples. These results indicate that cost and labor can be saved by selecting approximately ten percent of trees in a stand such as the one used in this study to obtain estimates for the first three measures, but more extensive and costly samples must be taken when estimating polymorphism and testing for deviation from the Hardy-Weinberg Equilibrium.

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