Speciation

In the 'hot tub' or hot springs as a salamander, conditions are small, clear, cool, and possess well-oxygenated streams and brooks with rocky bottoms. This luxurious form of living has its cons, including temperature and acidity dependency which results in limited to little capacity for survival in differing conditions.

The rocky bottoms of springs and brooks are layered with food sources including crustaceans, small frogs, and a variety of insects to suit your pallate preferences. Considering this, what do you think would be the most favorable inherited trait?