Transcript Adaptation, Natural Selection and Evolution

National 4 Biology
Key Area 5:
Adaptations for survival
National 5 Biology
Key Area 4:
Adaptation, natural selection and
the evolution of species
Cystic
Fibrosis
Cystic fibrosis is a genetic
condition in which the lungs
and digestive system
become clogged with thick
sticky mucus
Haemochromatosis
A genetic disorder causing the body to
absorb an excessive amount of iron from
the diet: the iron is then stored in various
organs.
What caused all of these?
Huntington's disease is an inherited
disease of the brain that damages
certain brain cells.
This can affect movement, cognition
(perception, awareness, thinking,
judgement) and behaviour
Huntingdon’s
Disease
Tay-Sachs disease is a rare and usually
fatal genetic disorder that causes
progressive damage to the nervous
system.
Symptoms usually appear at around 6
moths old and most affected children
will die by the age of 3.
Tay-Sachs
Syndrome
All of these conditions were
caused by a spontaneous and
random change or mutation in a
persons’ DNA
This mutation was inherited from
their parents.
Do you know what this is?
Malignant Melanoma (Skin cancer)
Not all mutations are inherited. Exposure to certain
factors, 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.
Factors that can lead to
mutations
Exposure to some chemicals can also lead to a spontaneous
mutation in our DNA that can lead to cancer.
Mutations
A mutation is a spontaneous change to genetic
material.
A mutagenic agent is a factor such as radiation
(gamma or X-rays), UV light or some chemicals
(e.g. those in cigarette smoke) that can
increase the rate of mutations.
Antibiotic resistance
• Random mutations in the DNA of
some bacteria have made them
resistant to antibiotics
• The rise of the “superbug”
• Major health concern
The Black Plague
• In the 14th century the
black plague killed 30%
of the population of
Western Europe
• Why did the other 70%
not die?
They had a mutation
that made them
resistance to the plague
bacterium
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)
Adaptations
• An adaptation is an inherited characteristic that
makes an organism well suited to its
environment/niche. This can be physiological,
structural and behavioural and help an organism
survive and reporduce in their environment.
Adaptations
Each group has been given a set of cards.
Match up the organism with its
adaptations.
Check your matches are correct and
draw out the following table in your
jotter
Organism
Adaptation
Kangaroo Rat Adaptations
• Lives in a burrow
underground
• Nocturnal
• Produces very
concentrated urine
• No sweat glands
Bilby Bandicoot Adaptations
• Large ears to
radiate excess
body heat
• Lives in a burrow
underground
• Nocturnal
• Produces very
concentrated urine
Cacti Adaptations
Polar Bear Adaptations
Camel Adaptations
Extreme examples of
interdependence
• All living things depend
on each other
• Some plants and
animals have evolved
‘hand in hand’ to help
each other survive
• These relationships are
very important because
neither one can survive
without the other.
Bull horn Acacia and Acacia ants
“Beltian
Bodies”
• Bull horn acacia and ants
depend on each other in
the following ways:
• a. large thorns provide
nesting for ants,
• b. Beltian bodies (and
nectar) provide food for
ants,
• c. ants swarm to defend
anything eating the tree,
• d. the ants clear an area
around the base of the
tree to reduce
competition for nutrients
Yucca and the Yucca moth
• For more than 40 million years there has been a
relationship between yucca plants and yucca moths.
• The moth’s larvae depend on the seeds of the yucca
plant for food, and the yucca plant can only be
pollinated by the yucca moth.
Darwin & 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.
Where it all started …
• The Galapagos Islands
• Located approximately
1000km from the coast
of Ecuador, South
America.
Darwin explored these
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
27
25 years later in 1859 Darwin wrote
“On the Origin of Species by Means of
Natural Selection”
• Two main points:
1. Species were not created in their
present form, but evolved from ancestral
species.
2. Proposed a mechanism for evolution:
NATURAL SELECTION
Survival of the Fittest
What does this mean?
Can you think of any examples?