1. Starter Activity:
On a show me board sketch a short story board to describe natural selection using one of the examples you have learnt about so far.

2. Speciation Learning Intention:
Natural selection brings about speciation.
Different factors can separate species and cause new species to evolve.
Success Criteria:
Explain what speciation is and what causes it to happen.

3. What does the word species mean?

4. Species
A species is a group of organisms that can reproduce to produce fertile offspring. Twig on Glow: Species (glossary)

5. The Tree of Life
Optional homework task: note the web address and look it up at home – noting down at least 5 key points (about how all life is connected) to share with the class.

6. What is speciation?
Twig on Glow: Origin of Species Watch the video clip and note down any key words on your show me board.

7. What is speciation?
Speciation is the formation of new species and natural selection is the mechanism that causes it to happen. This is the basis of the theory of evolution.

8. Factors involved in speciation
Speciation is the formation of a new species from existing species.
This depends on random mutations causing changes in genotype (genes) and phenotype (physical appearance) of some individuals.
The change allows these organisms to exploit the environment they are in, helping them to survive and pass on their genes to the next generation.

9. Factors involved in speciation
For speciation to occur three factors need to be involved:
Isolating mechanisms (to create sub-groups)
Random mutations (favourable)
Natural selection

10. Large population of one species
Sub-population A
Sub-population B
Mutation occurs
Isolation by a barrier
Species A
Species B
mutant
Natural Selection
Two species evolve
Barrier removed. Species A cannot breed with Species B. Speciation has occurred.

11. Isolating mechanisms 1. Geographical
Can you think of any geographical barriers
that might prevent species
from exchanging genes?

12. Isolating mechanisms 1. Geographical mountains rivers deserts
Oceans and seas 12

13. Isolating mechanisms 2. Ecological
Can you think of any ecological barriers
that might prevent species
from exchanging genes? 13

14. Isolating mechanisms
2. Ecological
temperature pH
humidity

15. Isolating mechanisms 3. Reproductive
Can you think of any reproductive barriers
that might prevent species
from exchanging genes?

16. Isolating mechanisms 3. Reproductive
Organisms like to reproduce at different times of year.
Lack of attraction
Sex organs are the wrong size
Pollinating mechanisms fail

17. What is speciation and what causes it?17

18. Discuss the meaning of each underlined word with your partner.
Speciation Summary
Speciation occurs after part of a population becomes isolated.
Mutations occur in each sub-population.
Natural selection selects different mutations in each group, due to different selection pressures.
Each sub-population evolves until they become so genetically different they are two different species.
Key Words
Discuss the meaning of each underlined word with your partner.

19. Speciation Learning Intention:
Natural selection brings about speciation.
Different factors can separate species and cause new species to evolve.
Success Criteria:
Explain what speciation is and what causes it to happen.

20. Research and presentation task…
Scottish Speciation
Research and presentation task…
Scottish examples of isolation leading to speciation:
Arran Whitebeam St. Kilda Wren Arctic Char
Choose one of the examples above and find out how isolation has caused it to evolve as a new species. You may present your work any way you like but you must work towards the following success criteria:
You must include… Where the organism is found and information about it’s habitat.
You should include… How the organism is adapted to where it lives.
You could include… Explanation about how speciation has caused this new species to evolve: What are it’s ancestors? Is it linked to another species? Why is it classed as a new species? Any other interesting facts?
Optional extension task