When hummingbird beaks become longer due to the neck of a flower becoming deeper, what pattern of evolution has occurred ?

Coevolution

Explanation:

Coevolution is a type of evolutionary change pattern that occurs when the interaction between two species of organisms brings about a change in the both species. In other words, both species of organisms evolve together as they interact together. The effect of the activity of one brings about a change in the other, and vice versa.

An example of coevolution can be seen in a flowering plant and pollinator relationship, just as seen between the hummingbird and flowering plants. The hummingbird evolve longer beaks in order to obtain nectar from the flower, while the flower in return evolve to grow deeper that contains sweeter nectars for the bird. Other pollinators without this adaptation of the hummingbird, like bees, would find it difficult to obtain this nectar from the flower.