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

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.

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

http://animal.discovery.com/mammals/camel/http://www.skjoldenllamas.net/en/index.php

http://animals.nationalgeographic.com/animals/mammals/brown-bear/http://worldwildlife.org/species/polar-bear

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

Have a go at the finch worksheet…

http://archives.focus.hms.harvard.edu/2006/090106/genetics.shtml

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?

http://animal.discovery.com/mammals/camel/http://www.skjoldenllamas.net/en/index.php

http://animals.nationalgeographic.com/animals/mammals/brown-bear/http://worldwildlife.org/species/polar-bear

Geographic Isolation

In pairs - Explain what you can see

happening at each stage of this diagram.

http://www.dr-evans.com/advancedbiology/evolution.html

So… How does this happen?

Geographic isolation

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

http://animal.discovery.com/mammals/camel/http://www.skjoldenllamas.net/en/index.php

http://animals.nationalgeographic.com/animals/mammals/brown-bear/http://worldwildlife.org/species/polar-bear

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.

1. Why is this an example of reproductive isolation? 2. What behaviour are the birds of paradise showing (male and female)?3. How have the birds of paradise changed as a result of natural selection?

Questions

1. Name 3 different ways in which isolation can cause speciation.

2. Explain why geographic isolation and the mechanism of natural selection causes speciation.

Switch papers and check your partnersIf 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.

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!!

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.

Short-beaked echidna - Platypus

Monotremes

-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).

Lowland tapir – Black rhinoceros

Odd-toed ungulates (Perissodactyls)

-Lowland tapir and black rhinoceros – these are both odd-toed ungulates (ungulates are basically mammals with hooves)

North African crested porcupine – American beaver

Rodents

African elephant - Rock hyrax

Afrotheria

-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.

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.

Earth structure

http://www.earthonlinemedia.com/ebooks/tpe_3e/earth_materials_structure/earth_interior.html

Draw the diagram and label the different parts.

The theory of plate tectonics

http://www.leeds.ac.uk/ruskinrocks/Plate%20tectonics.html

Plate Tectonics

Continental Drift

http://www.classroomatsea.net/general_science/plate_tectonics/cont_drift.html

Divergent plate boundary

New crust is created as two or more plates pull away from each other. Oceans are born and grow wider.

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.

http://www.platetectonics.com

http://gomyclass.com/geology10/files/lecshare1/html/web_data/file50.htm

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.

http://www.platetectonics.com

http://www.platetectonics.com http://www.platetectonics.com

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.

http://www.platetectonics.com

http://www.leeds.ac.uk/ruskinrocks/Plate%20tectonics.html

Plate tectonics and speciation

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.