Here's why:
* Original State: Before the Industrial Revolution, peppered moths were mostly light-colored with black speckles. This camouflage helped them blend in with lichen-covered trees, making them harder for predators to spot.
* Environmental Change: During the Industrial Revolution, pollution darkened the trees. The lichen died, and the trees became soot-covered.
* Selection Pressure: The darker moths were now better camouflaged on the darkened trees, making them less likely to be eaten by birds. The lighter moths became more vulnerable.
* Evolutionary Change: Over time, the population of peppered moths shifted. The dark moths had a higher survival rate, reproduced more, and passed on their genes, resulting in a higher proportion of dark moths in the population.
This is a classic example of natural selection in action. The environmental change (pollution) created a pressure favoring a specific trait (dark coloration), leading to a shift in the population over time.
This shift in the peppered moth population is a relatively recent phenomenon that has been documented and studied extensively, providing strong evidence for the theory of natural selection.
