Transcript Outline natural selection, isolation, plate activity without videosx

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://animals.nationalgeographic.com/animals/mammals/brown-bear/
http://animal.discovery.com/mammals/camel/
http://worldwildlife.org/species/polar-bear
http://www.skjoldenllamas.net/en/index.php
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://animals.nationalgeographic.com/animals/mammals/brown-bear/
http://animal.discovery.com/mammals/camel/
http://worldwildlife.org/species/polar-bear
http://www.skjoldenllamas.net/en/index.php
So… How does this happen?
Geographic
Isolation
In pairs Explain what
you can see
happening at
each stage of
this diagram.
http://www.dr-evans.com/advancedbiology/evolution.html
Geographic isolation
Both of these sets of organisms show examples of geographic isolation.
http://animals.nationalgeographic.com/animals/mammals/brown-bear/
http://animal.discovery.com/mammals/camel/
http://worldwildlife.org/species/polar-bear
http://www.skjoldenllamas.net/en/index.php
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 partners
If they are missing any key points let them know
Tell them what they have done well
1.
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•
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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 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
Monotremes
-Lowland tapir and black rhinoceros – these are both odd-toed ungulates (ungulates are
basically mammals with hooves)
Lowland tapir – Black rhinoceros
Odd-toed ungulates (Perissodactyls)
North African crested porcupine – American beaver
Rodents
-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
Afrotheria
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
Draw the diagram
and label the
different parts.
http://www.earthonlinemedia.com/ebooks/tpe_3e/earth_materials_structure/earth_interior.html
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
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
New crust is created as two or
more plates pull away from each
other. Oceans are born and grow
wider.
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
http://www.leeds.ac.uk/ruskinrocks/Plate%20tectonics.html
Transform Boundaries are where two plates
are sliding horizontally past one another.
http://www.platetectonics.com
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.
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.