1) Much of the theory and understanding in ecology, however, comes from ecosystems that are not undergoing rapid change.
2) The present study used this rationale to gain a better understanding of the female adolescents' social experience.
3) Perhaps these responses arrive to a greater understanding about humanity: beauty becomes the thing needed.
It depends a lot on context. 'understanding' collocates with many prepositions. Of course, 'of' is by far more common.