This is due to the complex inter-connections of species in ecological webs. B in a two-species interaction. Keystone species are those which produce strong indirect effects. We will develop our understanding of species interactions in ecological communities based on these building blocks. A mutualism is an interaction where both sides benefit.
Pollination is a common mutualistic interaction.
Facultative mutualisms are beneficial but not essential to survival and reproduction of either party. Obligate mutualisms are those that are essential to the life of one or both associates. We will examine an example of each. A fascinating facultative mutualism involves the Boran people of Africa, and a bird known as the honey guide. According to rock paintings, humans have collected honey in Africa for 20,000 years.