Pelage polymorphism in Pacific harbor seals

• Published in: Canadian Journal of Zoology
• Main Author: Kelly, Brendan P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1981
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Pacific; Phoca vitulina; Alaska
• Online Access: http://dx.doi.org/10.1139/z81-173; http://www.nrcresearchpress.com/doi/pdf/10.1139/z81-173

Regional variation in the percentages of harbor seals, Phoca vitulina, in light- and dark-phase pelages has been reported recently. Distributions of color phases among sex classes and age-classes and within family groups were examined during two pupping seasons on Tugidak Island and one season on Otter Island, Alaska. The ratio of light phase to dark phase in 880 pups with light mothers showed a good fit with expected values predicted by the hypothesis that the pelage dimorphism is controlled by a pair of autosomal alleles with light phase dominant over dark. A sample of 229 pups with dark mothers did not fit the hypothesis well. Color phase ratios did not differ between sexes or size classes but varied consistently with age-class. Differential selection against seals with light-phase pelage seems to be highest in the youngest age-classes at both localities.