Questions on Brook Trout (Salvelinus Fontinalus)

[Yiing Lin]

I have the following questions pertaining to brook trout 
(Salvelinus Fontinalus):

	1. Is it known around when brook trout became an
	   independent species?
	2. Where did brook trout reside/occur before they entered
	   the Great Lakes region?
	3. Are there any theories on when and where brook trout
	   entered the Great Lakes region?

I'm not sure if these questions are presently answerable, but
if someone could answer these questions and/or direct me to 
references which may be helpful in answering these questions, it
would be greatly appreciated!

						-Yiing
						 Cleveland, OH