[The flounder on four different backgrounds, showing that it assumes a colour pattern similar to that of the background. The change is accomplished by a visual stimulus transferred to the autonomic nervous system and stimulating the production of hormones which change the pigment cells.]

Generally when a biotic community reaches its climax stage it is stable. The stability of a community is directly proportional to the number of populations of different species present in it.

This is turn provides greater alternatives for food and shelter e.g. a large population of a species of eucalyptus or casuarina can be wiped out by a fungal disease or infection while when a mixture of many species is raised together only one may get affected while the others survive the disease.