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Inheritance, variation and evolution

The theory of speciation

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Explainer Video

Tutor: Holly

Summary

The theory of speciation

In a nutshell

Populations of the same species can become isolated from one another. Over time, natural selection can cause the populations to become so different that they can no longer interbreed and produce fertile offspring. This is speciation.

Speciation

Definition

Speciation is the development of a new species. A species is a group of similar organisms that can interbreed to produce fertile offspring. Speciation happens when different populations of the same species become so different that they can't interbreed to produce fertile offspring anymore.

Causes of speciation

1.	Speciation occurs when populations of a species are separated. This may be due to a physical barrier. Example An earthquake or flood may cause a physical barrier.
2.	The different populations of the same species are now geographically isolated from one another.
3.	The conditions in the two areas may be different. Example They may have different climates or they may have different food sources.
4.	Natural selection will cause different characteristics to become more common in the two populations.
5.	Eventually, natural selection will have caused the populations to be so different that they won't be able to interbreed to produce fertile offspring. Therefore, the two populations are now considered two different species.

Example

Biology; Inheritance, variation and evolution; KS4 Year 10; The theory of speciation

1.	Two populations of a species live together.
2.	The two populations are separated by some mountains that have formed due to tectonic activity.
3.	One side of the mountain is very sunny but the other has a very wet climate. Over many generations, natural selection will cause different characteristics to become more common in these two populations.
4.	Eventually the populations to be so different that they won't be able to interbreed to produce fertile offspring. So, the two populations are now considered two different species.

Learn with Basics

Length:

Unit 1

The process of natural selection

Unit 2

Evolution by natural selection

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Unit 3