Peppered Moths

Name: ______Peppered Moths

Darwin’s Theory of Natural Selection was extensively criticized before becoming widely accepted. At the time, people wanted more proof and examples of how and why organisms evolve by natural selection. Luckily, the peppered moths of Great Britain provided a great example of natural selection. The peppered moth is a night-flying moth. It is found in many regions of the world. There are two variations of the peppered moth in Great Britain. There is a white-bodied and black-bodied peppered moth. Before the Industrial Revolution, the majority of peppered moths were white- bodied in Great Britain. Their body color helped them camouflage against light- colored trees. Before the Industrial Revolution, the bark of trees was light colored. The bark was covered in lichen. Lichen is a composite of fungi and algae that grow on trees. There were not as many black-bodied moths because they did not camouflage well in the environment. Predators easily spotted them and so they were easy prey. Black-bodied moths had a characteristic (body color) that made them less successful in the environment. The Industrial Revolution caused widespread pollution. Factories produced soot. The soot covered tress and killed the lichen. Now the light-colored moths were not easily camouflaged. Instead, the dark-colored moths were hidden when resting on the tree bark. Predators easily spotted the light-colored moths and so white- bodied moths died off. Because the dark-colored moths were camouflaged, they survived and reproduced more black-bodied moths. A British scientist named Bernard Kettlewell performed research on natural selection of moths. He showed why moths are darker colored in polluted areas. Other scientists studied peppered moths. However, Kettlewell was the one who proved light-colored moths were easier for predators, specifically birds, to spot against a dark, polluted background. That is what caused light-colored moth population to drastically decrease after the Industrial Revolution.

Evolution 11 © Stephanie Elkowitz

Peppered Moths Continued Applying Darwin’s Theory of Natural Selection to Peppered Moths The peppered moth is one of the best-known examples of natural selection. Before the Industrial Revolution, nature selected the light-colored trait to be more successful. Light colored moths were more successful because they were better camouflaged in the environment. They thrived and reproduced. For this reason, the frequency of the light-colored trait was greater and more individuals were light colored. However, the Industrial Revolution changed the environment. After the Industrial Revolution, nature selected the dark-colored traits to be more successful because the dark color of soot on trees better camouflaged the darker colored moths. These moths thrived, reproduced and the frequency of the dark-colored trait increased.

Evolution 12 © Stephanie Elkowitz Name: ______

Peppered Moths Coloring

Follow the directions below: 1. Color and label the pre-Industrial Revolution Tree grey. 2. Label the patches on the pre-Industrial Revolution tree lichen. 3. Which peppered moths were most successful before the Industrial Revolution: Light-colored or Dark-colored? If light colored moths were more successful, color the moths grey. If dark colored moths were more successful, color the moths black. 4. Color and label the tree during the Industrial Revolution black. 5. Color and label the moths on this tree the same as you did in the pre-Industrial Revolution tree. 6. Color and label the post-Industrial Revolution tree back. 7. Which peppered moths were most successful after the Industrial Revolution: Light-colored or Dark-colored? If light colored moths were more successful, color the moths grey. If dark colored moths were more successful, color the moths black.

Before the Industrial During the Industrial After the Industrial Revolution Revolution Revolution