Place the characteristics along a scale depending on how inherited and
environmental they are
Objectives
Outcomes
Explain how sexual reproduction
promotes variation.
3: Identify adaptations and describe
what natural selection is.
Explain how Natural selection
leads to evolution.
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.
Task
Outcomes
For the picture you have been
given identify all the adaptations.
3: Identify adaptations and describe
what natural selection is.
How do these adaptations help
species survival?
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.
Adaptations for insect pollination
How are flowers adapted for pollination by insects such as bees
and butterflies?
colourful,
nectar, a
scented petals
source of food
attract insects
for insects, is
deep within
the flower
stiff anthers
and stigmas
are positioned
where insects
must brush
past them
large, sticky
pollen grains
become
attached to the
insect’s body
Adaptations for wind pollination
How are flowers adapted for pollination by the wind?
small, dullcoloured petals
anthers hang
loosely outside
flower so wind
can blow pollen
huge numbers
of light, tiny
pollen grains
long, feathery
stigma hanging
outside flower so
pollen can be
trapped
Lion
https://www.youtube.com/watch?v=YX8VQIJV
pTg
How do variations and ultimately
adaptations come about?
Outcomes
3: Identify adaptations and describe
what natural selection is.
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.
Variation
All species exhibit variation between individuals.
discontinuous
continuous
limited number of traits,
no intermediate forms
range or gradation
of characteristics
controlled by a few genes usually with
multiple alleles
controlled by many
genes (polygenic)
environment has little effect on these
characteristics
environment has a significant effect
e.g. human blood groups, antibiotic
resistance
e.g. stem height in plants, milk yield in
cows
Genotype and environment can both determine phenotype.
The
origin
of
genetic
variation
Genetic variation is heritable. It is this variation that natural selection acts upon.
The causes of genetic variation are:
Mutation
Sexual recombination

deletion, addition or substitution of a  independent assortment of
nucleotide
chromosomes in meiosis

deletion or translocation of part of
a chromosome

aneuploidy – loss or gain of a
single chromosome

polyploidy – the addition
of whole chromosome sets.

crossing-over during meiosis

random fertilization.
Environmental causes of variation
Organisms can be affected by their environment. Variation caused by the environment is
not heritable, so it is not subject to natural selection.
However, the ability of organisms to develop differently in different
environments can be genetic. This means organisms can evolve to be flexible.
Plants are a good example of this. The
number of leaves, growth pattern and
size of any individual plant is dependent
on the environment, e.g. availability of
light and nutrients.
What is natural selection?
Outcomes
3: Identify adaptations and describe
what natural selection is.
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.
Natural selection
Outcomes
3: Identify adaptations
and describe what
natural selection is.
5: Explain how
variation and
environmental
pressures lead to
natural selection.
7: Evaluate the role of
variation and natural
selection in the
process of evolution.
Key terms: variation, inherited, natural selection, evolution.
Outcomes
3: Identify adaptations
and describe what
natural selection is.
5: Explain how
variation and
environmental
pressures lead to
natural selection.
7: Evaluate the role of
variation and natural
selection in the
process of evolution.
Key terms: variation, inherited, natural selection, evolution.
Outcomes
3: Identify adaptations
and describe what natural
selection is.
5: Explain how variation
and environmental
pressures lead to natural
selection.
7: Evaluate the role of
variation and natural
selection in the process
of evolution.
Key terms: variation, inherited, natural selection, evolution.
Natural selection is still classified
as a theory.
How much evidence is required
to support a theory?
What about to refute one?
Outcomes
3: Identify adaptations and describe
what natural selection is.
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.
Natural selection challenge
Outcomes
Using the instrument you have
been give you must gather as
much food as possible in the time
frame.
3: Identify adaptations and describe
what natural selection is.
Who was the most successful?
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Why was this?
5: Explain how variation and
environmental pressures lead to
natural selection.
How does this show us natural
selection?
Key terms: variation, inherited, natural selection, evolution.
The
conditions
for
evolution
There are three factors needed for a population of organisms
to be able to evolve:

Variation – There must be differences between
the individuals in a population.

Heredity – The differences between organisms
must be heritable.

Means of selection – There must
be a mechanism or pressure that
selects some variables for the next
generation at the expense of others.
How did the work by Darwin on
his theory of natural selection
show a paradigm shift?
Outcomes
3: Identify adaptations and describe
what natural selection is.
5: Explain how variation and
environmental pressures lead to
natural selection.
7: Evaluate the role of variation and
natural selection in the process of
evolution.
Key terms: variation, inherited, natural selection, evolution.