Transcript 3.1c Natural selection

Starter:
What does the following term mean to you?
“Natural selection by
survival of the fittest”
Natural Selection
Learning Intentions:
• Natural selection/survival of the fittest occurs
when more offspring are produced than the
environment can sustain.
• Only the best adapted individuals survive to
reproduce, passing on the genes that confer the
selective advantage.
Success Criteria:
• Describe and explain, with examples, how natural
selection is described as survival of the fittest.
Starter:
What does the following term mean to you?
“Natural selection by
survival of the fittest”
Survival of the fittest
• This means the species most adapted to their
environment will survive and pass their genes
onto the next generation.
• It takes many generations. For some species
this takes millions of years (e.g humans).
Other species reproduce much more quickly
and evolve much faster (e.g bacteria).
Twig on Glow: Survival of the fittest.
Twig on Glow: Mutations and adaptations
Natural Selection
• Natural Selection occurs when more offspring are
produced than the environment can sustain.
• Well-adapted individuals are those which have
inherited characteristics such as the ability to avoid
predators, compete strongly for food, or resist
disease.
• They survive and reproduce, passing on the genes
that make them successful. They are said to have a
selective advantage.
• Natural Selection is sometimes called survival of the
fittest or Darwin’s theory of evolution.
Natural Selection
Charles Darwin visited the
Galapagos Islands and
recorded his findings about
the different species of finch.
He found that:
On each Island, the landscape and food source for
the finches was different.
The finches had adapted to their environment by
changing their body size and beak shape so that
they could eat food and survive.
This resulted in 13 different species being formed
over millions of years.
Darwin’s finches
• Darwin saw
different beak size
and shape on each
island.
• He concluded each
bird beak was best
adapted for the
food available on
each island.
Darwin’s finches experiment
• In groups of 4 you will play the role of
different finches, trying to survive and
pass you genes onto the next
generation.
Millions of years ago there was an island with two
species of bird. One had a long thin beak and the
other had a wide beak.
The island had a variety of trees and plants.
Beak Adaptation Experiment
Get into groups of 4 and collect the following equipment: 1 container of
food, 4 paper plates, 1 stop clock, 1 big spoon, 1 small spoon, 1 forceps & 1
tooth pick.
Number yourselves bird 1, bird 2, bird 3, or bird 4 in your group.
You will carry out 3 feeding experiments, following the instructions on the
board as you go.
You will be given 30 seconds to collect as much food as you can from the
feeding container, you may only use the “beak” you have been given and you
must place your food on your own paper plate for counting.
Each food type has the following energy values:
Rice= 1KJ
Small beans= 5KJ
Large seeds= 7kJ
Broad bean= 10KJ
•Use a copy of the table for your group to calculate the energy values for
Beak Adaptation Results Table 1
Rice
(1KJ)
Small
beans
(5KJ)
Large
seeds
(7kJ)
Broad bean
(10KJ)
Total
energy
consumed
Bird 1
(big
spoon)
Bird 2
(forceps)
Record in the table how many of each food each bird successfully
picked up with their beak from the bowl in 30 seconds.
Who survived?
• You must have at least 40kj to survive
and reproduce.
• Which birds were best adapted to
survive and pass their genes onto the
next generation?
Mutation!
• A random mutation
(change in the DNA)
has caused two new
species to develop.
• One has a large beak
and the other a
smaller thinner beak.
Beak Adaptation Results Table 2
Rice
(1KJ)
Small
beans
(5KJ)
Large Broad bean
seeds
(10KJ)
(7kJ)
Total
energy
consumed
Bird 1
(big spoon)
Bird 2
(small
spoon)
Bird 3
(forceps)
Bird 4
(tooth pick)
Record in the table how many of each food each bird successfully
picked up with their beak from the bowl in 30 seconds.
Who survived?
• You must have at least 40KJ to survive
and reproduce.
• Which mutations were advantageous?
• Which birds would have survived and
which would have eventually become
extinct?
Volcano!
• A volcano has erupted
and split the island in
two.
• One island has formed
where the beans grow.
• The other island has
formed where the seeds
grow.
• Half the class is on each
island.
Beak Adaptation Results Table 3
Rice
(1KJ)
Small
beans
(5KJ)
Large Broad bean
seeds
(10KJ)
(7kJ)
Total
energy
consumed
Bird 1
(big spoon)
Bird 2
(small
spoon)
Bird 3
(forceps)
Bird 4
(tooth pick)
Record in the table how many of each food each bird successfully
picked up with their beak from the bowl in 30 seconds.
Who survived?
You must have at least 40KJ to survive
and reproduce.
• Island 1- which birds got enough energy
to survive AND pass their genes on?
• Island 2- which birds got enough energy
to survive AND pass their genes on?
Bird Island Evolution
• On the original island the _________ beak bird was
best adapted to survive.
• Two new birds developed through random
___________ . These are changes to the ________.
• The new species most likely to survive was
_________.
• The birds best adapted for survival on the bean
island were________ and _________.
• The birds best adapted for survival on the _____and
_____ island were __________ and __________.
Natural Selection
Learning Intentions:
• Natural selection/survival of the fittest occurs
when more offspring are produced than the
environment can sustain.
• Only the best adapted individuals survive to
reproduce, passing on the genes that confer the
selective advantage.
Success Criteria:
• Describe and explain, with examples, how natural
selection is described as survival of the fittest.
Starter:
On a show me board write a short
conclusion about the Darwin’s Finches
experiment.
Natural Selection
Learning Intentions:
• Natural selection/survival of the fittest occurs
when more offspring are produced than the
environment can sustain.
• Only the best adapted individuals survive to
reproduce, passing on the genes that confer the
selective advantage.
Success Criteria:
• Describe and explain, with examples, how natural
selection is described as survival of the fittest.
More Examples of Natural
Selection: Peppered Moths
Peppered Moths can
be found in two
colours- black and
white forms.
• In unpolluted
areas, where
lichen grows on
trees. The white
form are
camouflaged.
More of the black
form are eaten by
predators.
In polluted areas trees become blackened by
soot and pollution. Lichen don’t grow. The
black form are camouflaged. More white
form are eaten by predators.
Peppered Moths and Natural Selection
• Peppered Moths can be found in two colours- _____and
w_______ forms.
• The black form arose from a r________ mutation.
• In unpolluted areas, where l_______ grows on tree’s, the
w_______ form are camouflaged. More of the b_____
form are eaten by predators, less can pass their g_____
onto the next generation. The next generation are mainly
white form.
• In industrial areas, tree’s become b_______ by soot and
pollution the black form are camouflaged. More w_____
form are eaten by predators, less can pass their genes
onto the next generation. The next generation are mainly
black form.
Peppered Moth Simulation
http://biologycorner.com/worksheets/pep
peredmoth.html
http://peppermoths.weebly.com/
Evolutionary biologists
• Some scientists think that competition
drives evolution.
• This theory is known as the Red Queen
Theory.
The Red Queen hypothesis
Literacy
• Red Queen refers to Alice in Lewis
Carroll's Through the Looking-Glass and
her explanation of the nature of
Wonderland:
• “Now, here, you see, it takes all the
running you can do, to keep in the same
place.”
The Red Queen Hypothesis
• The Red Queen hypothesis states that
the rate of evolutionary change is
dependant on the rates of change in
another species.
OR
• As one species adapts, a co-dependant
species also adapts.
Red Queen Example
• As the rabbits who are fastest survive to pass
on their genes, the whole rabbit population
becomes faster in the next generation.
• The next generation of fox only the fastest are
able to catch the faster rabbits. Therefore the
fox population also becomes faster.
Literacy
Are red heads becoming extinct?
• Read through the newspaper article.
http://www.dailymail.co.uk/sciencetech/
article-476430/Redheads-extinct-100years.html
• Answer the following questions…
Are red heads becoming extinct?
1. When does the article say red hair could
become extinct?
2. According to National Geographic, how much
of the worlds population has red hair?
3. What do you think the writer means by “ the
gene can be dormant”
4. According the article, what proportion of
Scots carry the red gene?
5. Where in the world do you think the red hair
mutation might have first arisen (Northern
Europe/ Africa/ America/ Australia/ Asia)?
Natural Selection
Learning Intentions:
• Natural selection/survival of the fittest occurs
when more offspring are produced than the
environment can sustain.
• Only the best adapted individuals survive to
reproduce, passing on the genes that confer the
selective advantage.
Success Criteria:
• Describe and explain, with examples, how natural
selection is described as survival of the fittest.