Adaptation, Natural Selection and Evolution

What caused all of these?

Cystic Fibrosis Haemochromatosi

s

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 20 Suncream

SPF 25 Suncream

SPF 50 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

A

B

C

Which antibiotic was resistant?

A C

B

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 particularanimal.

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?