If you hopes to know, then you have to have your eyes open:
http://www.freerepublic.com/focus/f-backroom/1343600/posts
They tracked mutations in the microbes which rendered them more successful at the higher temperatures.
They then started with a brand new unmutated batch of critters and did it again. Same mutations cropped up.
Furball, do you know the link?
Also, try Googling for the term "nylon bug."
Not good enough to display the whole panoply of macroevolution in vivo, but certainly good enough for a "proof of concept"...
Cheers!