Subraces
Beavers?
Those dwelling in Japan have become more accustomed to the cold and have become larger and more aquatic. Their more beaverish in appearance and mentality. Root based diet. More traditional values, making a home, raising a family, etc. Much more these are our ways and we’re happy with it. Proximity to rivers makes them more industrious and agriculturally based. Smaller families typically.
Ratses
Those dwelling in Australia are leaner, more lithe, more nimble, their proximity to the forest is more fruit and vegetable diet. More adventurous and more on wanting to encounter other people a lot more. More mouse, rat, etc. More nomadic and prolific, large families.