Polar bears appear to be genetically divided into discrete populations based on their geographic locations. But the differences among polar bear population is least likely to be expected in the light of present migration or movements of polar bears. Scientists believe that there seems to be an insignificant variation of mitochondrialDNA(mtDNA) in polar bear populations in Chukchi and Beaufort Seas. Nonetheless the protein electrophoresis and mitochondrial DNA cannot settle genetic difference among populations.
Polar Bear Genetics
Biologists have recently come up with the substantial differences regarding genetic distances in four populations living in Canada. According to them the long-distance migrations of polar bears do not seem to cause the absolute genetic mixing of populations. Scientists also discovered the fact that the population in the Canadian Arctic is likely to show greater genetic differences in comparison to those living in the polar basin.
The studies also suggest that the polar bear populations show greater genetic variations as compared to black bear or even brown bear populations. One of the most widely distributed arctic animals is a gray wolf (Canus lupus)—second only to polar bear. The genetic distances in ice bears are thought to be at the lower extreme of the distances noted in the gray wolf species. The mtDNA pattern also points to the fact that the polar bear population has greater perhaps the greatest genetic variation of all bear species. But the brown bears and black bears of the old world did have greater variation than the present-day polar bear population.
While studying historical evidences of the bear species regarding their genetic differences the kodiak bear (a brown bear subspecies) also confirms greater genetic varieties—comparing it to the polar bears of today. Unlike genetic variations the structural or morphological differences in polar bears are thought to be almost consistent across the range. Scientists have also confirmed one fact concerning genetic variation in polar bears.
Read More: Polar Bear Evolution
The fact is that polar bears go down to only one evolutionary lineage. They belong to a single evolutionary unit (panmictic). The conclusion is based on comparatively small genetic distances in white bear populations. Over a period of thousands of years the polar bear population might have experienced significant genetic exchange which led to low levels of population differentiation.
In spite the fact that all other bear species (except polar bears) show greater variation the findings suggest that the polar bear’s genetic variation is nearly the same as that of black or brown bear population. The greatest genetic variation is found in black bear population then followed by brown bears and the least deviation in polar bears.
Over the past few decades the directional gene flow of polar bears has increased ranging from Canadian Archipelago population, Eastern Polar Basin, Southern Canada, to the Western Polar Basin.