AQA GCSE Speciation(Biology) - Science Worksheets

AQA GCSE Speciation (Biology)

Speciation

Speciation is the formation of new species from an existing species.

It usually happens when populations become separated and evolve differently over time.

Darwin and Wallace

Charles Darwin and Alfred Russel Wallace both developed the theory of evolution by natural selection.

Wallace independently came up with the same idea after his travels to Indonesia.

In 1858, they published their ideas together.

This led Darwin to publish his book “On the Origin of Species in 1859″.

Impact on biology:

This changed how scientists understand life on Earth, it showed species are not fixed and led to modern evolutionary biology.

Wallace and Speciation

Wallace collected evidence from around the world.

He studied:

-Animal colouration (e.g. warning colours)
-How species are distributed

He suggested that new species form when populations become separated.

His work helped develop early ideas of speciation, but modern evidence has improved the theory.

How Speciation Happens

1.A population has variation
2.A group becomes isolated (e.g. by a river, mountain, or distance)
3.Different environments cause different selection pressures

(Selection pressures are factors in the environment that affect an organism’s chances of survival and reproduction.)

4.Natural selection leads to different adaptations
5.Over time, genetic differences increase
6.The groups can no longer interbreed
7.A new species has formed

Theory of speciation developing over time

Early ideas from Darwin and Wallace contributed to the theory of speciation.

Darwin’s work laid the foundations because the idea of natural selection by evolution will eventually lead to a new species being formed if a population is isolated

More evidence later from:
-fossils
-genetics (DNA evidence)

Modern theory is more detailed and supported

The theory of speciation has developed over time as new evidence has become available.

Speciation is a result of evolution. Over long periods of time, small changes can lead to entirely new species.

Practice Questions

1.What is speciation?

2. A population of birds becomes separated by a river. Explain how this can lead to the formation of two species.

3.Describe the contribution of Alfred Russel Wallace to evolutionary theory.