Evolution > selection

The case of the peppered moth (Biston betularia) is a commonly reported example of the change in a species from one form (or morph) to another, as a result of natural selection in different environments. It serves as a good introduction to the process of evolution by natural selection and a good example of population dynamics.

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.

Artemia salina (brine shrimps – commonly known as 'sea monkeys') kept in a brightly-illuminated aquarium provide an easily-observed and sustainable ecosystem for classroom-based ecological and behavioural studies by students at Key Stages 3 and 4 or Scottish Stages S1–S4 (Dockery and Tomkins, 2000).

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.

This involves placing baits of different colours (the ‘worms’) in a place where birds are known to search for food. Uneaten ‘worms’ are collected (or counted) regularly and the ‘worm population’ is restored with more coloured bait in the same proportions as the bait that remains. After several cycles of predation and breeding, the proportions of each colour in the population will have changed – simulating directional