Download Adaptation, Natural Selection and Evolution

Adaptation, Natural
Selection and Evolution
Cystic
Fibrosis
Haemochromatosis
What caused all of these?
Huntingdon’s
Disease
Tay-Sachs
Syndrome
Do you know what this is?
Malignant Melanoma (Skin cancer)
Investigating the effect of
varying suncreams on UV beads.
No
suncream
SPF 50
suncream
SPF 20
Suncream
SPF 25
Suncream
Time how long it takes for each
bead to change colour.
SPF Factor
Number of beads which
have changed colour over
time.
2
4
6
8
10
0
20
25
50
Plot a graph of your results and draw a valid
conclusion.
Mutations
A mutation is a random change to genetic
material.
Factors such as radiation and UV light can
increase the rate or mutations.
Antibiotic Resistance
B
A
C
Which antibiotic was resistant?
B
A
C
Is mutation a good thing?
• In the 14th century the black plague
killed 30% of the population of Western
Europe
• Why did the other 70% not die?
Mutations
Advantageous – bacterial resistance to
antibiotics.
Neutral – Ear lobes/no ear lobes.
Disadvantageous – Malignant Melanoma
(skin cancer)
Why are mutations
important?
Mutations are important because they
increase variation within a species.
This allows species to adapt to be better
suited their environment.
Think, pair, share
An animal you know about and how
it is
adapted to it’s environment?
Adaptations
Each group has been allocated a particular
animal.
You must find out;
- how your animal is adapted to it’s
environment?
- how does this adaptation affect the
animal’s survival?
Survival of the Fittest
What does this mean?
Can you think of any examples?
Natural Selection
• Organisms which are best adapted to
their environment are more likely to
survive and reproduce.
• This means they pass on the most
desirable genes to the next generation.
Natural Selection - Steps
• Individuals in a species show variation
caused by mutations.
• Some individuals survive and breed.
• Advantageous genes are passed on from
generation to generation. Giving the new
generation and selective advantage.
Question Time!
1. Darwin used the term “survival of the
fittest”. Explain what this means.
2. Pet shops sell white and brown rabbits.
White rabbits are easily seen by foxes.
Use Darwin’s theory of evolution to
explain why white rabbits are rare in
the wild.
Speciation
• The process by which a new species is
formed.
• What is the definition of a species?
Speciation – Step by Step
Two parts of a population become isolated from each
other by an isolation barrier.
This can be geographical, ecological or reproductive.
Speciation – Step by Step
Geographical – rivers, mountains, sea.
Ecological – extreme changes in temperature, pH or
humidity.
Reproductive – a lack of attraction between the
populations.
Speciation – Step by Step
Different mutations take place in each
population.
Speciation – Step by Step
Different selection pressures on each
population cause the advantageous
mutations to become more frequent in
the population.
Speciation – Step by Step
Following more natural selection the
two populations become genetically
different to each other.
Speciation – Step by Step
Population A cannot breed with population
B.
A new species has been formed.
Question Time!
1. Name 3 isolation mechanisms.
2. Wallace found two species of monkey
on either side of the Amazon river.
How did Wallace explain that they
came from a common ancestor?
3. Lemurs evolved on Madagascar but not
in Africa. Explain why?