Polar bears and grizzly bears share a common ancestor (similar to you and your cousin sharing a grandparent); Describe some selective pressures that may have caused speciation between these two types of bears.

Lasting genetic similarities make the two bears biological sister species, more closely related to one another than to any others. ... But Ursus maritimus has also evolved to match its polar environment, growing a longer snout than brown bears' and larger, paddle-like paws, both of which aid polar bears in hunting seals.