Fun fact: Grizzlies and Polar Bears are the same species according to the Biological Species Concept.
Meaning they interbreed in the wild (somewhat rare), and produce viable offspring that can have babies as well.
We’re actually noticing this happening more and more with climate change. As Grizzly populations move further and further north, they’re encountering polar bears more often and are more likely to mate. Some scientists actually think within the next couple centuries due to arctic sea ice pretty much disappearing polar bears will either go extinct, or interbreed with grizzlies so much that there isn’t a “pure” polar bear left. Most likely a mix of both.