The peppered moth ( _Biston betularia_) provides a textbook example of rapid evolution.
* Before the Industrial Revolution, the majority of peppered moths were light-colored, blending in with the lichen-covered trees they lived on. This coloration provided camouflage from predators like birds.
* During the Industrial Revolution, soot from factories darkened the trees, making the light-colored moths more visible.
* A darker, melanic form of the peppered moth arose, offering better camouflage on the darkened trees. These moths had a survival advantage and reproduced more successfully, passing on their genes.
* Over a few decades, the darker moths became the dominant form in polluted areas. This change in frequency of the two moth types (light and dark) occurred rapidly, demonstrating evolution in action.
Key factors:
* Natural Selection: The changing environment (darkened trees) favored darker moths, leading to their increased survival and reproduction.
* Genetic Variation: The existence of both light and dark forms of the peppered moth provided the genetic material for natural selection to act upon.
* Rapid Time Scale: The evolution of the peppered moth occurred over a relatively short period, demonstrating how quickly evolution can happen in the face of strong selective pressure.
This example highlights how evolution is not a slow, gradual process, but rather a dynamic response to environmental changes. The peppered moth story showcases the power of natural selection in driving rapid evolutionary changes.
