Smith, an evolutionary ecologist, studies the interactions between evolution and ecology, while other K-State researchers study ecosystem ecology, allowing them to learn how living and nonliving parts in a habitat work together. Smith said the main approach of ecosystem ecology is to describe how the flow of energy and the cycling of minerals through the system works together. That's not the approach he takes, though.
Natural selection is a choice as to which one better uses the environment to make offspring.
You can ask why is this one better than the other. It's a way of approaching why rather than just describing how things are. It's hard to make a question that involves both in the answer. If you're asking different questions you do different things. And I'm asking different questions.