How is it possible that landmass that once supported rabbits went from ecosystem to a snow covered tundra?

Question

The landmass could support a rabbit population ( among other things) of which 99% are brown coated. In addition there was a population of carrots. Through Some process, this landmass slowly enters the northern latitudes. Millions of years later the ecosystem has become an Arctic like tundra. the rabbit population is now composed of mostly white-coated rabbits; and there are no carrots, only a cold weather form of turnips.

Answer 1

This process is called species diversity. It has happen with many animals, and will continue to happen due to climate changes. The Arctic fox is another example of this process. They have the ability to change coat color when winter sets in.