Sources of Allozymic Variation in Thuja occidentalis in Southern Ontario, Canada

1991

S. 100-105

4 Abb., zahlr. Lit. Ang.

Unselbständiges Werk

200051266

Allozyme variation at 11 loci for seven enzyme systems was studied in three swamp and three cliff populations of Thuja occidentalis L. in southern Ontario. Overall genetic variability was extremely small, with 82% of loci monomorphic for all samples. Inbreeding coefficients indicated that no significant inbreeding occured at any site. (Formel)-tests showed no significant differences in allele frequencies among the six stands; unbiased genetic distances among all stands were very small (average 0.0015), and no correlation between genetic and geographic distance was found. Of the total variability, 96.9% was among trees within stands, 1.9% among stands from the same habitat, and only 1.2% between habitat types. No variability was found when several branches from the same tree were compared. The number of effective migrants between cliffs and swamps per generation was estimated as 21, and between sites as 12. It was concluded that the patterns of intraspecific variability, at the allozyme level, of T. occidentalis in southern Ontario are not adequately described by the concept of "wet" and "dry" ecotypes.