Evolution > interaction

The case of banded snails – Cepaea nemoralis and Cepaea hortensis – is a well-known example of natural selection. The adaptation of populations of species of this snail in different environmental conditions is used as a case study for evolution in action. Teachers can use Cepaea to encourage discussion about how species change, and to clarify misunderstandings about the natural processes leading to species change.

In this simple procedure, grains of rice are used to model small organisms, and students act as predators selecting food during limited time spans. Over a number of generations, the proportion of grains of rice of each colour in each population will change if students select one colour in preference to another. This is a simple model for natural selection resulting from predation.