Answer to Question #101755 in Evolution for Nibedita Rudra

Question

Explain the concept of co-evolution theory with the help of an example of host-parasite relationship.

Answer 1

The term co-evolution is used to describe cases where two or more species affect each other's evolution in a mutually dependent manner . Each party in a co-evolutionary relationship exerts selective pressures on the other, thereby affecting each other's evolution. Co-evolution functions by reciprocal selective pressures on two or more species, analogous to an arms race in an attempt to out-compete each other.The host-parasite relationship is one of the most classic examples of co-evolution. Co-evolution of hosts and parasites involves the reciprocal evolutionary change that occurs specifically between these classic antagonists, and is predicted to be ubiquitous, given the intimate relationships that parasites share with their hosts and the strong selective pressures that each can exert on each other.

This co-evolution is driven by the reciprocal evolution of host resistance that inhibits parasite establishment or survival within the host and parasite infectivity. This antagonistic co-evolution between resistance and infectivity traits may lead to either increased or decreased host or parasite fitness.