Every species needs its own "niche." This term is a combination of the role, function, and place of an organism in its environment. 

The extinction of dinosaurs about 65 million years ago opened many niches for new occupants that could become new species. When dinosaurs became extinct, the niches in which they lived became available for other species. Natural selection especially favored the existing small mammals because they were smarter than most other species and their warm-bloodedness allowed them to thrive in many climates. 

Jungles, like this one in Costa Rica, provide many niches for many plant and animal species. What would happen to these niches if we chopped down the trees in the jungle? ... or if there was a drought that dried up the swamps and river?

Do you think there would be as many niches in the desert?

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