Amazingly beautiful animals. Makes me think of polars. Did you know they have black skin?
I had not even thought of that, but you are right!
It shows how sensitive colour is in changing from its population group. Its not a big deal.
So why not just a wee trigger could switch colours and make it stick? Within biolgy/genes there must be a trigger. in these errors it shows how close the trigger is perhaps. likewise explain human color change that happened within a generation or so of the flood/babel.