Evolution through natural selection
Evolution through natural selection

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Evolution through natural selection

3 Natural selection in the guppy

3.1 Introduction

The purpose of this section is to consolidate your understanding of the theory of evolution through natural selection by looking at a specific example. The guppy (Poecilia reticulata) is a small fish whose natural habitat is small streams in northern Trinidad, but it is also a popular aquarium fish. Male and female guppies are very different in appearance (Figure 2); they are said to show sexual dimorphism as male guppies are very much more brightly coloured than females. We will consider how natural selection influences bright coloration in male guppies, and we will do so by considering each of Darwin's four propositions in turn.

Figure 2
Figure 2 A variety of guppies produced by selective breeding by aquarists. The two females in the foreground are relatively plain. The four brightly coloured males show variation in the number, size and colour of the spots on their bodies.

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus