I've expanded to the dawn tree before goals were out, the only thing it unlocked was a white dawn goal. When i click on the tree, it shows this goal which is to have 10 white epic dragons, reward I presume is the light habitat booster. Other boosters were unlocked by other goals, not this one, and I think they are similar goals in the sense of getting a red booster unlocked if you have 10 epic red dragons... etc