On this topic in a biology class. A good example of this process is the relationship between a particular type of occasion plant and a certain type of ant. The occasion need some ways to protect itself against herbivore,animals that eat plants. In this end, it provides the occasion with this protection. This is how it works. The occasion has two large hollow thorns, extending from it's leaves that provide the ant with a great place to live.And in return,the ant protects the occasion by attacking and stinging any animals that tries to eat the plant as far as the ant's concerned. It's guarding its house.So the plant in the insect basically protect each other.
But the key here is,this is really crucial,the key is that long ago the occasion did not have these enlarged hollow thorns in the ants originally did not attack animals this way. But as time went on occasions and ants that lived in the same geographic area, develop these traits that are specifically designed to help each other out. We know this because other close relatives of these ants and the occasion plants do not possess the same traits that is other occasions located elsewhere do not have the hollow thorns and other ants related to the answer we've been talking about, do not attack animals in the same way. Only these two specific and in occasion species developed in this way.