What is Coevolution ?
There is considerable evidence that supports an interesting theory that two individual species can affect each others evolution in reciprocal fashion. In other words, it is possible for two species to interact whereby an evolutionary change in Species #1, for instance, triggers a change in the Species #2 in response to the evolutionary change in the first species. Since they both evolve because of, or as a result of, evolutionary changes taking place in their relationship, the process is called coevolution.
In its simplest form, coevolution can be seen in predator-prey relationships. If a prey species evolves ways to avoid predation through the natural selection process, the predator species in response, will evolve its own more effective and efficient ways of capturing prey. Plants and animals have what many consider an intertwined evolution.
Some scientists believe that flying insects evolved in response to a change that first evolved among plants. According to this theory, natural selection favored plants that produced reproductive structures above the ground level, above the reach of foraging animals. In theory, any reproductive structures, which were not eaten could remain functional and survive to produce offspring. These offspring would have a higher probability of also possessing reproductive structures positioned out of the reach of ground animals. In time, and after many generations, the plant population would have evolved so that it formed a new and different species, one with reproductive structures located high off the ground.
The reproductive structures positioned up in the air provided a resource that served to select for only those insects that could fly. In this way natural selection of a plant was able to drive the selection of animals with flying abilities. These flying insects alternatively might have represented a beneficial selection force for plant to evolve flowers by acting as pollinators. In this way, a very selective and effective pollination process could have evolved from the coevolution that took place between plants and animals.
Coevolution is readily apparent in the relationships found between flowers and their pollinators. There are unique pollination relationships that exist between a single species of plant and a specific pollinator. Flowers may have specific structures that permit entry to only one species; they may have colors, patterns of color, or fragrances that are only identifiable by and correspond only to a specific pollinators characteristics. The evolutionary advantage of this specificity is that the plant does not have to produce pollen that is wasted on other plants, and on the other hand, the pollinator has a food source all to itself.