If one population, such as lets say a hawk decreases the niche, or the importance of an animal or its effect in the ecosystem, on the mice. the mice population increases. or it can be lets say plants and bugs, the lady bug goes away and the other bugs eat the plant
There are so many examples for that in different areas, like TPT1 experiment carried out in our lab recently.Here's one link: http://www.alfa-chemistry.com/tpt1-cas-167218-46-4-item-290583.htm