RESUMEN
Grizzly bears are abundant in the region of the Prudhoe Bay oil fields in northern Alaska. We used field observations and molecular genetic data to identify parent-offspring and sibling relationships among bears in this region. We determined genotypes at 14 microsatellite DNA loci and the cytochrome b gene of mitochondrial DNA (mtDNA) for 36 bears. We identified 17 possible mother-offspring pairs and 8 possible father-offspring pairs. This includes verification of the relationships of 14 mother-offspring pairs identified from field observations. Three additional mother-offspring pairs and all eight father-offspring pairs were determined from genetic and age data. Relatedness coefficients based on numbers of shared alleles between individuals were as expected: approximately 0.50 for parent-offspring and sibling pairs and approximately 0.75 for a father-offspring pair resulting from a father-daughter mating. The level of genetic variation (mean number of alleles per locus = 6.6, mean heterozygosity = 70%) and allele frequencies in grizzly bears in the Prudhoe Bay region are similar to those in other parts of the species' range.
