Mutualism is a type of symbiotic relationship between two species in which both species benefit from the interaction. Unlike predation, parasitism, and commensalism, mutualism involves a close and mutually beneficial relationship between the two interacting species. In this type of relationship, both species rely on each other for survival and reproduction.

Mutualism is not included in the group of predation, parasitism, and commensalism because it is a unique type of interaction that differs from these three types. While the other three types of relationships involve one species benefiting at the expense of the other, mutualism involves both species benefiting.

Examples of mutualism include the relationship between bees and flowers, where bees collect nectar and pollen from flowers and in turn, help to pollinate the flowers. Another example is the relationship between bacteria in our gut and our digestive system. The bacteria break down food that we cannot digest on our own, and in turn, we provide them with a habitat and nutrients to survive.

In conclusion, mutualism is not included in the group of predation, parasitism, and commensalism because it is a unique type of symbiotic relationship that involves both species benefiting from the interaction.