Mutualism is a biological interaction between two organisms, where each individual derives a fitness benefit (for example increased survivorship). Similar interactions within a species are known as co-operation. It can be contrasted with interspecific competition, in which each species experiences reduced fitness, and exploitation, or parasitism, in which one species benefits at the expense of the other. Mutualism and symbiosis are sometimes used as if they are synonymous, but this is strictly… (More on Mutualism)