coevolution

The evolution of two or more interdependent species, each adapting to changes in the other. It occurs, for example, between predators and prey and between insects and the flowers that they pollinate.

Coevolution is a rare form of evolution. By definition, it requires that two species adapt to evolutionary changes occurring in each other. An example of this reciprocal adaptation would be the development of mutualistic relationships between plants and the insects that prey upon them. As the plant develops defenses (like the oils of species in the mustard family), the insects develop counter weapons (cabbage butterflies have metabolic adaptations that can safely break down these toxic compounds).

The process that occurs when two species influence each other during evolution. For example, an insect may evolve specialized parts that allow it to feed on a specific flower, whereas the flower evolves to facilitate pollination by that particular insect.