Step-by-step explanation:
Environmental factors such as changes in weather, environment, and resources on survival can all vary in the outcome of genetic variation. Since every organism does not live under the same circumstances, they will have to adapt to the environments that they are in.
For example, if there was an island with nuts suitable for large-beaked birds to eat, then there will be a large population of large-beaked birds on the island. However, if the island flooded, the nuts would wash away, leaving the large beaked birds having to look for other resources for survival, so by evolution, their beaks would begin to vary in size depending on what they begin eating.
Another example can be peppered moths. Centuries ago, these species used to be light in color, as they lived on light-colored trees. However, due to the growth of industries and factories, trees in the environment began to discolor and turn dark, so these moths would stand out from the trees and be a targeted species for food. Therefore, they would need to evolve to a darker shade to blend in with the trees for survival.