Unit 3 * Evolution Lesson 1 * Mutations and Artificial Selection

What is evolution and why is it important?
The mechanism that drives evolution is
natural selection.
Natural Selection: the way in which nature
favours the reproductive success of some
individuals within a population over others.
Genetic diversity must be present for nature
to favour some individuals over other
Mutations are the source of genetic variation
What mechanisms have we studied that
increases this genetic diversity?
A substitution is a mutation that exchanges one
base for another (i.e., a change in a single
"chemical letter" such as switching an A to a G).
-Such a substitution could cause a small change in
the protein produced.
For example,sickle cell anemia is caused by a
substitution in the beta-hemoglobin gene, which
alters a single amino acid in the protein
Heritable disease
Chronic pain caused
by RBCs moving
through blood
Stroke, other
Insertions are mutations in which extra base
pairs are inserted into a new place in the
Deletions are mutations in which a section of
DNA is lost, or deleted.
Neutral mutation - a mutation that does not
result in any selective advantage
or disadvantage.
Harmful mutation - any mutation that reduces
the reproductive success of an individual and is
therefore selected against; harmful mutations
do not accumulate over time
Beneficial mutations - are favoured by natural
selection and accumulate over time
Artificial selection - directed breeding in which
individuals that exhibit a particular trait are
chosen as parents of the next generation;
artificial selection is used to produce new
breeds or varieties of plants and animals
1. Choose a useful species that can be bred in
2. Breed a large number of individuals.
3. Choose a trait that you wish to favour, such as
large size, a particular colour, or sweetness.
4. Identify individuals that exhibit the favoured
trait most strongly.
5. Breed only these individuals to produce the next
generation of individuals.
6. Repeat Steps 4 and 5 over many generations.
Artificial Selection is limited by the genes that
are present in the current population.
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