The term evolution in biology refers to change of a species over time. Over time, as species adapted to changes in the environment, the species evolved into what we see today. Often these changes are small changes that occurred over many years.
Coevolution is a term that refers to the evolution of two species that are interdependent, each affecting the evolution of the other. Coevolution happens when the two species have a close relationship, such as in the following cases:
3. Species that are competitive
4. Species with a mutualistic relationship-a relationship where both species benefit from the relationship.
In predator/prey relationships, as the prey evolve to have more advanced skills to elude the predator, the predator has to evolve more advanced hunting skills. An example of a predator/prey coevolution is the African honey bee and the honey badger. The honey badger loves honey, and it evolved to have long claws to tear into hives and thick skin, making it nearly immune to the stings. So, the African honey bees evolved so that when attacked, they can create a massive swarm to attack the honey badger-as they die, they secrete a pheromone that calls the others to continue to attack.
Scientists believe that many plant/pollinator relationships are the result of coevolution. Plants have evolved over time to have bright flowers with stripes and patterns to attract specific insects or birds. In return the insects and birds have evolved so that they can efficiently extract nectar from the plants. One example would be the hummingbird with its long, skinny beak. It is perfectly adapted to extract nectar from flowers. Some plants even emit specific scents that attract insects. For example, orchids emit a smell that is akin to the pheromones secreted by female bees and wasps. Scientists believe plants evolved this ability at the same time that the insects were evolving.
Another common example of coevolution is specific to the Acacia plant and a species of ant known as the Acacia ant. These two species have evolved together so that the ants protect the plant from herbivores that would eat it. In return, the Acacia plant provides the ant with a place to build nests for larvae (hollow thorns).