Narrator: This is Science Today. An analysis of seven tropical forests around the world reveals that nature encourages diversity by selecting for less common trees as the trees mature. Biology professor, Christopher Wills, of the University of California , San Diego , led the study.
Wills: People of course have been questioning why diversity should be maintained. They've been proposing theories for why it should be maintained, but there's been very little good hard evidence about what impact is going on at the ecosystem level. So our study shows that these processes really are happening in a wide variety of different ecosystems in the tropics.
Narrator: In forests throughout the New and Old World tropics, Wills found that older trees are more diverse than younger ones – meaning, diversity is actually selected for as each of the forests mature.
Wills: Now that we've established that there are active processes going on, we can begin to ask how can we decide among the various theories that help to explain this diversity?
Narrator: For Science Today, I'm Larissa Branin.