The relationship of polar bears to other bears. (a) A rooted phylogenetic tree adapted from . Polar bears are thought to have diverged from brown bears from the ABC Islands in Canada after these brown bears had diverged from other brown bears. Black bears and other bear species are more distantly related to both polar bears and brown bears. The pictures show (b) a brown bear (not from the ABC islands) (Ursus arctos) and (c) a polar bear (Ursus maritimus). Original bear images courtesy of Peter Haase, Carl Lund and Michael Petersen (Copenhagen Zoo).