1.   Fewer plants equate to fewer ecological niches and fewer species of animals to fill them.

2.   Old ecological niches were destroyed in the process and new ones opened up.

3.   Some thing or things have to happen for a microbe to escape its previously harmless ecological niche and reach critical Mass.

4.   This in turn has led to rapid evolution to fill the vacant or new ecological niches.

5.   They had fulfilled various ecological niches which were occupied on the American continents by other birds.

6.   But biological studies show that no matter how many coyotes are killed, they reproduce rapidly, and quickly fill every ecological niche available.

7.   Color vision is a complicated evolutionary development, and it evolved in a specific ecological niche for a specific purpose.

8.   In that case, as Hasiotis speculated, flowering plants did not so much open up new ecological niches for insects, including bees and wasps.

9.   Most strikingly, the survival of the forest has depended on them, for the tigers occupy the ecological niche of weeding out trespassers there.

10.   My goal was to make it as self-sustaining as possible, by treating the tub as an ecosystem and making sure that every ecological niche was filled.