Download adaptation-natural-selection-and-evolution12

National 4 Biology
Key Area 5:
Adaptations for survival
National 5 Biology
Key Area 4:
Adaptation, natural selection and
the evolution of species
Quick Question
1. Name one biotic factor that can affect
biodiversity.
Food Availability or Predation or Grazing or Disease or competition
2. Name the piece of sampling equipment
used to measure light intensity
Use a light meter
3. Describe one precaution to be taken
when using this piece of equipment
All group members should stand well clear of the meter to prevent
shadows
National
5
outcomes
By the end of the lesson you
will be able to …..
• Define the word Mutation.
• Give examples of different mutations
• Give examples of mutagenic agents
Do you know what this is?
Malignant Melanoma (Skin cancer)
Not all mutations are inherited. Exposure to certain
factors (e.g. UV light in sunlight) can cause spontaneous
mutations that lead to cancer.
Factors that can lead to
mutations
• We now know that exposure
to most radiation (UV, gamma
and even X-rays) can be
carcinogenic.
• X-ray technicians will either
leave the room during an Xray or wear a lead lined vest
Mutations
A mutation is a random and spontaneous change to
genetic material (DNA).
A mutagenic agent is a factor that can increase the rate
of mutations
E.g.
• Radiation (X-rays),
• High temperatures
• some chemicals (e.g. mustard gas).
Quick Question
1. Describe what is meant by a mutation.
A mutation is a random and spontaneous change to genetic material
(DNA).
2. Match up the mutagenic and its possible
effect on living tissue:
A. UV radiation
1. Lung Cancer
B. Chemicals in cigarette
smoke
2. Mouth Cancer
C. Mustard Gas
3. Skin Cancer
Some mutations are ‘neutral’
• Evidence of the mutations may be
visible
• Makes no difference to the overall
health of the organism
Mutations can be….
Advantageous: e.g. bacterial resistance to
antibiotics.
Neutral:
e.g. Free Ear lobes or
attached ear lobes.
Disadvantageous: Malignant Melanoma
(skin cancer)
Why are mutations
important?
• Mutations are the only source of brand
NEW GENES (alleles) in a population.
• Mutations are important because they
increase variation within a species.
• This allows species to adapt to be
better suited their environment.
Mutations – The Science of
Survival (45 minutes)
(Up to 21 minutes)
Can you now ….
• Define the word
Mutation.
• Give examples of
different mutations
• Give examples of
mutagenic agents
Quick Question
1. Give two examples of mutagenic agents.
UV light or X rays or the chemicals in cigarette smoke
2. Match up the mutation and its effect on
survival:
A. Advantage
1. Widow’s peak hairline
B. Disadvantage
2. Cystic Fibrosis
C. Neutral
3. Antibiotic Resistance in
Bacteria
National
4
outcomes
By the end of the lesson you
will be able to …..
• Define the word ‘adaptations’
• Give examples of behavioural,
physiological and structural adaptations
Variation in a species
• All populations show variation in appearance
and in genetics.
What type of
variation is show
in the beetle
population?
• Variation in a population is caused by a random
spontaneous mutation
• It may or may not give that organism an advantage
Adaptations in Action!
Watch this clip and write down any adaptations
that you see….
BBC Hunting & Escaping : Camouflage
(6:39)
Amazing Animal Adaptations and
Evolutionary Problem Solving (1 hour)
Adaptations
• An adaptation is an
inherited characteristic
that makes an organism
well suited to its
environment.
• This increases their
chances of survival and
being able to reproduce.
• Adaptations can be:
– structural
– physiological
– behavioural
Predator, e.g. a lionGood eyesight for
hunting prey
Strong jaws and sharp
teeth for ripping flesh
Sharp claws for gripping
prey
Hunting Lesson - Wildlife Specials: Lions - Spy in
the Den - BBC
Prey, e.g. rabbit
Ability to
move quickly
Good
hearing for
detecting
predators
Bat
Uses sound
to detect
prey
Skin
between its
fingers to
form a wing
Bats hunting their prey - Top Bat - BBC
Eagle
Strong and hooked beak to kill and
tear flesh off of their prey
Large talons to grip onto prey
Pelican
Large ‘pouch-like’
beak for scooping
up fish from the
water
Webbed feet for swimming
Finding Nemo Pelicans & Seagulls Scene
Quick Question
1. Which bird would eat the rabbit and why?
Can you now ….
• Define the word
adaptations
• Give examples of
behavioural,
physiological and
structural
adaptations
Key Area Assessment
• You are now ready for your next
National 4 Key Area Assessment
• This will be one question on Key Area 5
“Adaptations for survival”
• This will be done during your next lesson
Quick Question
1. What food are the animals adapted to eat
and why?
Lion
Fish
Pelican
Seeds
Finch
Meat
National
5
outcomes
By the end of the lesson you
will be able to …..
• Describe how animals become adapted
to their niche
• Give an example of animal that has done
this
Natural Selection
Charles Darwin (1809 – 1882)
Theologist and self-taught
naturalist.
Believed living things evolved.
Suggested evolution happed by
natural selection or “survival
of the fittest”.
Gathered detailed evidence from
voyages (e.g. The Galapagos
Islands) to support his theory.
Darwin did not provide an
explanation of how features
were passed on.
Darwin explored the
Galapagos Islands from
April through October
1835.
Inspired by the nature of
the island chain
When and where he started
thinking about what was to
become his theory of
evolution by natural
selection.
Animals live there that are
found nowhere else on
earth.
This makes them endemic
30
Endemics
Unique adaptations of
Galapagos endemics inspired
Darwin
– 13 species of finches
– 1 penguin species
– 1 giant tortoise species
– 1 marine iguana species
– 7 species of lava lizard
– 14 species of sea cucumber
– 1 species of sea lion
– 1 species of hawk
– several species each of
mockingbirds, doves, owls,
flycatchers, and yellow
warblers
31
Darwin’s Finches
•Darwin was most inspired by the birds in the
islands
•He observed that finches had adapted to have
different types of beak.
•He proposed that they all evolved from a
common ancestor
Darwin’s Finches
• Darwin proposed that the Finches had all evolved from a common
ancestor but had developed a different shape and size of beak.
• This allows the finches to eat different types of food. This
reduces competition.
• This gave them a “selective advantage”.
1.
2.
3.
4.
5.
Different beaks for different
niches
Copy the table below
Using chopsticks, transfer as many of the grains of the rice into a
plastic beaker as you can in 60 seconds
Calculate the total number of grains transferred by your group
Enter the number in the table in you jotter
Repeat 2-4 using a teaspoon and then a spatula
Chopsticks Beak
Group 1
Group 2
Group 3
Group 4
Total Average
Teaspoon Beak
Tweezers Beak
Different beaks for different
niches
1. Which “beaks” were best and least adapted for
picking up the grains of rice?
Best – teaspoon, Least - chopstick
2. Which group had an advantage over the others?
Teaspoon beaks
3. How could results have been more reliable?
Repeat for Reliable Results
4. As an 18 year old, you transfer populations of
each type of finch to an island where the only
food source is rice. You return to the island as a
98 year old. Using the term “natural selection”,
predict the numbers of each type of finch on
your return to the island.
Teaspoon – high, tweezers – moderate, chopsticks – extinct.
Quick Question
1. Decide if each statement is true or false. If it is
false then correct the underlined word.
Statement
T or F
Correction
A mutation is a random and
spontaneous change to protein.
F
Genetic material
OR DNA
Adaptations can be structural,
physiological or behavioural.
Darwin’s Finches evolved
different shapes and sizes of
beaks to increase competition
T
F
Decrease OR
reduce
National
4&5
outcomes
By the end of the lesson you
will be able to …..
• Explain what the phrase “survival of the
fittest” means.
• Describe the process of natural
selection
Survival of the Fittest
•Darwin proposed that organisms better
adapted to their environment survive.
•He called this ‘survival of the fittest’
Natural Selection
Is a process in which individuals that
are better adapted to their
environment survive and breed, whilst
those less well adapted die before
reproducing.
Charles Darwin (1809 – 1882)
Theologist and self-taught
naturalist.
Believed living things evolved.
Suggested evolution happed by
natural selection or “survival
of the fittest”.
Gathered detailed evidence from
voyages (e.g. The Galapagos
Islands) to support his theory.
Darwin did not provide an
explanation of how features
were passed on.
genotype
Word
Selective
pressure
phenotype
Selective
advantage
Meaning
The type of genes an organism has, e.g. a
gene for blue eyes.
The physical appearance of an organism.
An aspect of the environment that
selects one characteristic over another,
e.g. climate, predators or disease.
The characteristic of an organism that
enables it to survive and reproduce
better than other organisms in a
population in a given environment
Natural
Selection
Sexual reproduction results in more offspring
than environment can support
Offspring show inherited variation. They have
different genotypes and phenotypes.
Struggle for Survival:
Exposure to different selection pressures
Some
rabbits
die of
disease
Struggle for Survival:
Exposure to different selection pressures
Some
rabbits with
thinner
coats die of
exposure
Some
rabbits die
of starvation
Some slower
rabbits are
caught by
Those rabbits poorly adapted to their environment die before predators
reproducing.
Rabbits with the
selective advantage
(best adapted to their
environment) survive and
reproduce.
The alleles (genes) that give the selective advantage are passed on.
Eventually, the species changes over time.
Quick Question
1. Darwin used the term “survival of the fittest”.
Explain what this means.
Organisms better adapted to their environment survive!
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.
White rabbits easily seen and eaten by foxes
Die before reproducing
Brown rabbits are best adapted to avoid predation – have selective
advantage
Brown rabbits survive and reproduce, passing on genes to give selective
advantage
National
5
outcomes
By the end of the lesson you
will be able to …..
• Give an example of ‘high speed’ natural
selection
Natural Selection in Action
• He was wrong!
• Two ‘modern’
day, high speed
examples are:
– The evolution of
antibiotic
resistance
bacteria
– The Peppered
moth
Natural selection
occurs far too
slowly to be
witnessed in a
man’s lifetime.
The Story of The Peppered Moth
Once upon a time in pre-industrial
England……
Birch tree
with pale
bark
Moths with light wings were
camouflaged on trees
Can you spot the
pale moth????
Moths with dark wings were easy
to spot by predators
What would you expect to happen
to the ratio of each type?
Along came the industrial
revolution – and lots of pollution
Tree trunks were discoloured by
pollution
Can you spot the
dark moth????
Now the black moths had the
selective advantage
What would you expect to happen
to the ratio of each type?
As coal burning stopped the trees
returned to their natural colour
Moths with light wings were camouflaged
on trees again
Paragraph 1….
• Before the industrial revolution in Britain, most
peppered moths were pale.
• Pale moths were well camouflaged against the pale
trees that they rest on.
• Moths with a mutant dark colouring were easily
spotted and eaten by birds.
• This meant the pale moths were better adapted to
their environment, giving them the selective
advantage over the darker variety.
• Therefore the pale variety survived to reproduce
and their numbers increased.
Paragraph 2….
• Pollution in industrial areas blackened the
birch trees with soot.
• This meant that the mutant dark moths were
now camouflaged, while the pale variety
became more vulnerable to predators.
• This meant the dark moths were now better
adapted to their environment, giving them
the selective advantage over the paler
variety.
• Therefore the dark variety survived to
reproduce and their numbers increased.
Quick Question
1. Use these 6 bullet points to write a
brief paragraph about Natural Selection
– variation exists
– struggle for survival
– best adapted organisms survive
– reproduce
– inherited characteristics are passed on
– species change over time
• Variation exists in natural populations.
All organisms struggle for survival. The
best adapted organisms survive and
reproduce. This means their inherited
characteristics are passed on. As this
process is repeated the species change
over time to become as well adapted to
their environment as they can be.
Quick Question
1. Decide if each statement is true or false. If it is
false then correct the underlined word.
Statement
T or F
Correction
Evolution a process in which individuals
that are better adapted to their
environment survive and breed
F
Natural Selection
A characteristic of an organism that
enables it to survive and reproduce
better than other organisms is a
selection pressure.
F
Selective
advantage
A species is a group of interbreeding
organisms whose offspring are fertile.
T
National
5
outcomes
By the end of the lesson you
will be able to …..
• Define the word species
• Describe the process of speciation
Species
Think back
to
biodiversity!
• 8.7 million named species at last count (2011)
• Estimates between 13 - 100 million in total
• A group of interbreeding organisms whose
offspring are fertile
Different Species
STERILE
OFFSPRING
X
ZEBRORSE
Young that are unable to
produce more of their own
kind on reaching maturity
• Some species are closely related meaning that they
can interbreed.
Species
• 8.7 million named species at last count (2011)
• Estimates between 13 - 100 million in total
• A group of interbreeding organisms whose
offspring are fertile
Where have all these species come from?????
National
5
outcomes
By the end of the lesson you
will be able to …..
• Define the word species
• Describe the process of speciation
Speciation
• A species is “a group of interbreeding
organisms whose offspring are fertile”
• Speciation is the process by which a
new species is formed.
Speciation – Step by Step
1.
1. A large population of interbreeding
organisms of the same species live
together in the same habitat.
1.
2.
The population is divided into 2
smaller groups by an isolation
barrier.
2.
The sea acted
as a
geographical
barrier for the
endemics on the
Galapagos
Islands.
72
Geographical Barrier
Geographic isolation occurs when two populations
are separated by geographic barriers such as
rivers, mountains or the grand canyon.
Kaibab
Abert
Copyright Pearson Prentice Hall
Ecological barrier
• Ecological barriers cause a change in the
environment.
• This change is caused by an abiotic factor,
e.g. temperature, O2 concentration and pH.
E.g. fish living in different
positions in the water
column.
Reproductive Barriers
Reproductive barriers may occur when:
• two or more species reproduce at
different times.
Reproductive Barriers
Reproductive barriers may occur when:
• Changes in courtship behaviours make them
‘unattractive’ to the opposite
Copyright Pearson Prentice Hall
This can be:
Geographical  rivers, mountains, sea.
Ecological
 extreme changes in
temperature, pH or humidity.
Reproductive  a lack of attraction between
the populations
1.
2.
2. The population is divided into 2
smaller groups by an isolation
barrier.
Speciation – Step by Step
3.
3. Different random and spontaneous genetic
mutations take place in each population.
This may or may not give the organism a
selective advantage.
Speciation – Step by Step
4.
4. Different conditions exist on either side of the
barrier.
This creates different selection pressures on each
population.
Individuals with a selective advantage survive and
reproduce.
Speciation – Step by Step
5.
5. Following more natural selection the two
populations become genetically different to each
other. The isolation barrier is removed.
Population A cannot produce fertile young with
population B. A new species has been formed.
• Look at how ONE
species change
changes over
time!
Great Speciation Video
• http://www.youtube.com/watch?v=Q2vs
G77PZ80