POPULATION GENETICS OF THE WHITE-PHASED “SPIRIT” BLACK BEAR OF BRITISH COLUMBIA
Article first published online: 5 OCT 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 66, Issue 2, pages 305–313, February 2012
How to Cite
Hedrick, P. W. and Ritland, K. (2012), POPULATION GENETICS OF THE WHITE-PHASED “SPIRIT” BLACK BEAR OF BRITISH COLUMBIA. Evolution, 66: 305–313. doi: 10.1111/j.1558-5646.2011.01463.x
- Issue published online: 25 JAN 2012
- Article first published online: 5 OCT 2011
- Accepted manuscript online: 19 SEP 2011 09:58AM EST
- Received June 20, 2011 Accepted August 26, 2011
- assortative mating;
- color polymorphism;
- gene flow;
- genetic drift;
- heterozygote deficiency;
The Spirit (or Kermode) bear is a white-phased black bear found on the northwest coast of British Columbia, and is one of the most striking color polymorphisms found in mammals. A single nucleotide polymorphism at the melanocortin 1 receptor gene (mc1r) locus is the cause of this recessive w variant. Recently, evidence suggests that the white color provides a selective advantage during salmon hunting. Here we examine the effects of favorable selection, gene flow, genetic drift, and positive-assortative mating in an effort to understand the establishment and maintenance of this polymorphism and the observed heterozygote deficiency for mc1r but not for microsatellite loci. It appears that genetic drift was important in the establishment of the w allele and that the selective advantage was important to counteract immigration from populations without the w allele. Positive-assortative mating can result in a deficiency of heterozygotes but needs to be quite high to result in the large deficiency of heterozygotes observed, suggesting that other factors must also be contributing. Examination of population genetic factors, singly and jointly, provides insight into the establishment and maintenance of this unusual polymorphism.