The mating system of polar bears: a genetic approach

• Published in: Canadian Journal of Zoology
• Main Authors: Zeyl, E., Aars, J., Ehrich, D., Bachmann, L., Wiig, Ø.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2009
• Subjects: Barents Sea; Ursus maritimus
• Online Access: http://dx.doi.org/10.1139/z09-107; http://www.nrcresearchpress.com/doi/full-xml/10.1139/Z09-107; http://www.nrcresearchpress.com/doi/pdf/10.1139/Z09-107

Parentage analysis data for 583 individuals genotyped at 27 microsatellite loci were used to study the mating system of polar bears ( Ursus maritimus Phipps, 1774) in the Barents Sea area. We discriminated statistically between full and half-siblings identified through only one common parent. We document for the first time multiple paternity in polar bears. We demonstrated for both sexes low fidelity to mating partners over time. We did not detect any significant difference between the age distribution of adult males at capture and the age distribution of males siring cubs. This might indicate that the male’s age and size are less indicative of the reproductive success than previously thought. This is further supported by a rather long mean litter interval of 3.9 years for males siring several litters. The mating system of polar bears in the Barents Sea appears to be promiscuous, usually with a single successful father siring full siblings within a year, but with consecutive litters of a mother being fathered by different males. We discuss how population density, landscape characteristics, and adult sex ratio might influence the mating system of polar bears. This is of particular importance for management decisions such as, e.g., implementing sex ratios in hunting quotas.