Natural selection – light and dark peppered moths

Integrated ScienceGenetics & EvolutionAges 14–15

A moth population made up of light-colored individuals (dd) and dark-colored individuals (DD, Dd) rests on a tree trunk. Each generation, birds eat more of the moths that stand out against the bark; the survivors breed to produce the next generation, and the allele frequency and phenotype ratio shift gradually on the chart. Change the background color (tap the trunk, or let it darken gradually from industrial pollution) and the selection pressure to see the direction of evolution change.