This animation shows how quickly an advantageous mutation can spread through a mouse population over multiple generations.

Mutations with even a small selective advantage can lead to rapid evolution of populations. This animation uses equations from population genetics to simulate how quickly a new, advantageous fur color spreads through a rock pocket mouse population. The selective advantage discussed in the animation corresponds to the selection coefficient (s). Even with only a modest advantage (a relatively small value of s), evolution can happen in as few as 100 generations.

This animation is a clip from a 2005 Holiday Lecture Series, Evolution: Constant Change and Common Threads. Depending on students’ background, it may be helpful to pause the animation at various points to discuss the different scenarios presented.