Electrophoretic techniques which can be used to aid the identification of clones are described. An example using members (putative ramets) from 10 morphologically distinct putative clones of trembling aspen is presented. In this example, it is demonstrated that phenotypically uniform groups of trees (putative clones) can actually be composed of several electrophoretically distinct genotypes.

Inheritance of allozymes of 12 polymorphic loci was demonstrated using haploid megagametophytic tissues of viable seed from a total of 47 white spruce trees in one stand. In general, allozymes segregated as expected in a 1:1 ratio. However, one allozyme of phosphoglucose isomerase (Pgi-2) did not segregate as expected. Significant deficiency in two different heterozygous combinations was observed. This result could be indicative of selection against the allozyme. The level of genetic variability in this stand of white spruce was similar to average levels of variation observed with many conifer species. Overall, an excess of heterozygotes was observed in the mature population. However, after 9 years of storage in a seedbank, no more than random selfing could be detected in the viable filial generation. Significant heterogeneity in allele frequency distribution of several loci was observed in the pollen pool in this stand. The calculated ratio of genetically effective males to females in this population was only 0.4. These results were interpreted as evidence for changes in the spatial genetic structure of the population, likely marking demes of related individuals, and restricted effective transmission distances of male gametes. Some implications for tree improvement programs are discussed.

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Levels of electrophoretically detectable variation at 19 loci were estimated in 36 populations representing the natural range of Larixlaricina (Du Roi) K. Koch. Results of this survey indicated that the species has levels of genic variation comparable with those of other species of woody perennials with extensive transcontinental ranges. There was no evidence of significant departures from Hardy–Weinberg expectation. However, on average, populations of this species were more differentiated and more genetically divergent from one another compared with many randomly mating tree species. A discriminant analysis of the genotypic structure of the populations analyzed indicated a general east versus west pattern, with populations in the Great Lakes basin being further differentiated. Present-day population distribution, population density, and reinvasion routes after the last glaciation could account for the observed patterns of genic variation.

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