1. Starter
In pairs recall one example of natural selection that we saw in the last class and write down:
the name of the species
the characteristic that had been selected for
why it improves the fitness of that species

2. Natural selection and biodiversity
Learning outcomes
You will all be able to:
State that isolation can lead to different species being produced
Most of you should be able to:
Outline the mechanism of natural selection in relation to speciation
Describe and explain that speciation occurs as a result of reproductive and geographic isolation of populations.

3. What adaptations do these animals show that increase their fitness for their environment?

5. Summary Darwin’s finches - evolution on a small scale
Change in available food means finches with some beaks survive while others die out
This is natural selection
There are many different ‘pressures’ which can influence evolution - change in habitat, predators, mate preferences
Apply this on a worldwide scale….
....BIODIVERSITY
Darwin’s finches are a great example of a situation where the mechanism for evolution can be evident on a smaller scale.
In our example, natural occurrences such as a change in available food caused some beaks to be more successful – this is natural selection - because the spoon beak is ‘selected’ over the chopstick beak.
This is just one example of natural selection – other examples could be a change in available habitats, new predators (e.g. an introduced species), different mate preferences or simply something like geographical separation (e.g. the finches blown to the Galapagos by storms would become different to those still on the mainland).
Now imagine increasing the scale and timescale of this and applying it to the whole world – across all the different habitats, conditions and continents and the sheer number of different selection pressures that could occur by chance – is it any wonder that we have such a diverse number of animal species on the planet? We haven’t even touched on all the different forms of life e.g. plants, algae, fungi, micro-organisms….

6. Have a go at the finch worksheet…

7. Here are two sets of species who both came from the same ancestor – what happened to cause these two distinct species to develop from their ancestor?

8. So… How does this happen?
Geographic Isolation
In pairs - Explain what you can see happening at each stage of this diagram.

9. Geographic isolation

10. Both of these sets of organisms show examples of geographic isolation.

11. Reproductive isolation
Species might not be able to reproduce with one another because their reproductive organs no longer fit.
The size may make it impossible.

12. Why is this an example of reproductive isolation?
What behaviour are the birds of paradise showing (male and female)?
How have the birds of paradise changed as a result of natural selection?

13. Questions
Name 3 different ways in which isolation can cause speciation.
Explain why geographic isolation and the mechanism of natural selection causes speciation.

14. Switch papers and check your partners If they are missing any key points let them know Tell them what they have done well 1.
Reproductive organs no longer fit
Size of organisms
Reproductive behaviour
Geographic isolation
Land barrier
Water barrier 2.
Populations become separate through geographic or reproductive isolation
They are no longer able to interbreed
Gene flow between the two populations is interrupted
Two separate species develop in response to different selective pressures.
Even when the geographical barrier is removed the species have now changed so much that they can no longer interbreed.

15. Starter – In groups
Which species are more related? Have a look at the sheet and in your pairs try to decide which species you think are the most closely related. HINT: It might not be as easy as you think!!

16. Learning outcomes You should all be able to:
Identify that the planet has different layers
Outline natural selection as a mechanism for speciation.
Most of you should be able to:
Explain how plate activity has influenced evolution and biodiversity.

17. Short-beaked echidna - Platypus
Short-beaked echidna and platypus – many people think that the echidna is most closely related to the porcupine, as they both have spines, but this is not the case!
The short-beaked echidna and the platypus are both primitive mammals belonging to a group known as the ‘monotremes’ (these are egg-laying mammals).
Short-beaked echidna - Platypus
Ask students to provide answers and also give their reasoning as to why they have paired certain species.
Short-beaked echidna and platypus – many people think that the echidna is most closely related to the porcupine, as they both have spines, but this is not the case!
The short-beaked echidna and the platypus are both primitive mammals belonging to a group known as the ‘monotremes’ (these are egg-laying mammals).
These Australian mammals evolved after the continents divided, and any resemblance the echidna has to the porcupine has arisen due to convergent evolution – they have each independently evolved to fit a similar niche in their environment.
Monotremes

18. Odd-toed ungulates (Perissodactyls)
Lowland tapir and black rhinoceros – these are both odd-toed ungulates (ungulates are basically mammals with hooves)
Lowland tapir – Black rhinoceros
Lowland tapir and black rhinoceros – these are both odd-toed ungulates (ungulates are basically mammals with hooves)
Odd-toed ungulates (such as horses, tapirs and rhinos) are known as ‘perissodactyls’.
Odd-toed ungulates (Perissodactyls)

19. North African crested porcupine – American beaver
North African crested porcupine and American beaver - these are both rodents.
Rodents are characterised by a pair of continuously growing incisors in each of the upper and lower jaws. Need to gnaw to keep them shortened.
Rodents

20. African elephant - Rock hyrax
African elephant and rock hyrax - both of these species belong to an African species group called the afrotheria, and so are more closely related that anything else on the worksheet.
However, the closest relative of the elephant is actually the manatee – in fact, if you look closely at a manatee’s flippers, they look very similar to an elephant’s foot.
African elephant - Rock hyrax
African elephant and rock hyrax - both of these species belong to an African species group called the afrotheria, and so are more closely related that anything else on the worksheet.
Other afrotheria species include golden moles, elephant shrews and aardvarks.
However, the closest relative of the elephant is actually the manatee – in fact, if you look closely at a manatee’s flippers, they look very similar to an elephant’s foot (a squashed one!) as you can clearly see the toenails on the ends of the flippers.
Afrotheria

21. Mammalian species diversity exercise - answers
Blue whale - Moose
Although these species look nothing alike, the blue whale and moose are closely related.
They belong to a group called the Cetartiodactyls, which is a combination of cetaceans (whales and dolphins) and artiodactyls (even-toed ungulates such as pigs, deer, sheep, antelope and cattle).
Surprisingly, artiodactyls are more closely related to cetaceans than they are to the perissodactyls (the odd-toed ungulates like the rhino) – this means artiodactyls have a more recent common ancestor with the cetaceans than with perissodactyls.

22. Earth structure Draw the diagram and label the different parts.

23. The theory of plate tectonics

24. Plate Tectonics

25. Continental Drift

26. Divergent plate boundary
When a diverging boundary occurs on land a 'rift', or separation will arise and over time that mass of land will break apart into distinct land masses and the surrounding water will fill the space between them.
New crust is created as two or more plates pull away from each other. Oceans are born and grow wider.

27. Convergent plate boundary
Here crust is destroyed and recycled back into the interior of the Earth as one plate dives under another. These are known as Subduction Zones - mountains and volcanoes are often found where plates converge.

28. Transform plate boundaries
Transform Boundaries are where two plates are sliding horizontally past one another.
The San Andreas fault zone in California is a transform fault . The Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yr. 

29. Plate tectonics and speciation

30. Plate tectonics causing biodiversity
Based on what you now know about plate tectonics and natural selection…
Explain how you think plate activity has influenced evolution and biodiversity.