The Case of the Peppered Moth

1. The Case of the Peppered Moth E. Coleman 2008

2. English Countryside - Pre-Industrial Revolution. Predominant tree species had light-colored bark or were covered with light-colored lichen. 2. Peppered moths were almost all light in color.

3. Though it was rare, occasionally a dark-colored peppered moth would appear. What have we observed about traits within populations?

4. What allows for different variations of colors in these peppered moths? Mutations • Mutations are changes in the genetic material (DNA) of an organism. • They sometimes result in offspring that are very different from their parents. • They are rare. The mutation that results in the dark form of the peppered moth occurs about 1 in every 200,000 offspring or .0005% of the time. • Mutations are the ORIGINAL source of all variation in species.

5. By the mid-1800’s the Industrial Revolution was in full force. Throughout England factories were spewing soot and smoke into the air.

6. The bark of trees and the lichen growing on them darkened from the accumulated soot and pollution. • And observers noticed more and more peppered moths were of the dark variety.

7. PRIMARY PREDATOR OF THE PEPPERED MOTH ? BIRDS ! Where are the moths?

8. Within a few decades “dark” became the predominant form of the Peppered Moth. BEFORE: Light bark, mostly light moths • What caused the change in coloring of the Peppered Moth? • How would Darwin explain it? • These are the questions you will explore in this activity. AFTER: Dark bark, mostly dark moths

9. WHAT IS HAPPENING TO PEPPERED MOTHS NOW? • Graph shows % dark moths, 1800 - present. • What has happened since about 1960?