CLONAL STRUCTURE OF ARCTIC DWARF BIRCH (BETULA GLANDULOSA) AT ITS NORTHERN LIMIT

• Published in: American Journal of Botany
• Main Authors: Hermanutz, L. A., Innes, D. J., Weis, I. M.
• Other Authors: Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Arctic; Baffin Island; Northwest Territories; Baffin; Dwarf birch
• Online Access: http://dx.doi.org/10.1002/j.1537-2197.1989.tb11370.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fj.1537-2197.1989.tb11370.x; https://onlinelibrary.wiley.com/doi/full/10.1002/j.1537-2197.1989.tb11370.x

Betula glandulosa Michx. (Betulaceae) at Tarr Inlet, Baffin Island, Northwest Territories reproduces primarily by vegetative layering with little, if any, viable seed production or seedling recruitment. Information from polymorphic enzyme loci revealed 15 three‐locus genotypes with a single genotype usually dominating each of the nine sampled sites. Clonal reproduction combined with self‐incompatibility may be one factor contributing to a decreased seed set by reducing the probability of xenogamy. However, multiple genotypes were found at some sites providing an opportunity for cross compatible pollen to effect fertilization. The lack of seed set in these areas appears to be due to additional factors inhibiting sexual reproduction. Based on pollen records, the present limited distribution of Betula glandulosa on Baffin Island represents the remnants of once more widely distributed populations, and the failure of sexual reproduction at the northern edge of its range may be responsible for the decline in abundance. Genotypic diversity observed in the Tarr Inlet area appears to be residual from a once sexually reproducing population. No evidence was found for differential selection of genotypes indicating that random processes are probably eroding the genotypic diversity during the decrease of population size in this species.