Transcript Aim: How does evolution occur by natural selection?

Aim: How does evolution occur
by natural selection?
Do Now: What is an adaptation?
Can adaptations be acquired?
Explain.
HW: January 2014 #13-48
Evolution 3
How Does Evolution Occur?
EVOLUTION is a slow change in a
_________
species over time.
 Evolution occurs by a process called
NATURAL SELECTION
_________________________.

Read this cartoon, what do you think NATURAL SELECTION
is?
Lamarck’s theory of Evolution
Lamarck believed that by the selective USE
or DISUSE of characteristics, organisms
lost or acquired certain traits that would be
passed on to the offspring.
Darwin

Considered the “_________”
father
of evolution.

Charles Darwin traveled to the
Galapagos
___________________
, an uninhabited
island
environment,
where he studied evolution
Darwin’s Finches
(_________________)
Natural Selection

KEY
NATURAL SELECTION is the _________
to Darwin’s theory.

According to this theory, evolution is
NATURE . Only the
controlled by __________
SURVIVE and
organisms that are able to ___________
REPRODUCE will pass on their genes.
________________
Natural Selection vs.
Artificial Selection
________
People select the
desirable traits that
will appear in the
Offspring.
____________
Environment selects
the desirable traits
that will appear in
the offspring.
Conditions that are vital to
Evolution:
 Overproduction
 Variation
 Struggle For Survival
 Best Adapted To Survive
 Darwin
did NOT have knowledge
genetic basis of
of the _________
inheritance
Overproduction
More offspring are produced than can
survive (most die young).
___________
Overproduction
leads
to
 Organisms such as bacteria, fish, insects,
COMPETITION!!
high
and rabbits have ________
reproductive
rates because the chance that their young
minimal
will survive is___________.

Variation
 Variation:
Individuals
differences in their
have__________
appearance, structure, or genes.

Source of variation:
Sexual Reproduction (sperm + egg)
 _______
Meiosis (Indp. Ass. & Crossing
 __________
Over)
Mutation
 __________ (Change in DNA)
Mutations
 Mutations
change the base
sequence of ________.
DNA
 Most
mutations are ___________,
HARMFUL
but some can help the organism
____________.
SURVIVE
Best Adapted To Survive
The __________________
ENVIRONMENT chooses
which traits have adaptive value.
 An individual that has traits favorable
in a certain environment will live to
reproduce
_____________
and pass on those
die out.
traits, others will _____

Adaptive Value

Adaptive Value: a change that produces a trait
survive
that helps an organism____________.
Camouflage
 Ex: _____________

If all the members of a species were the same
wipe outthe
then an environmental change would _______
entire species. VARIATION
____________ increases the
chance that some members of a species will
survive
_____________.
Struggle For Survival

“Survival of the fittest”

BEST suited will survive
Only those _________
finite (limited)
because of competition for ______
oxygen, water, food, and shelter
resources (___________________________)
Conditions that lead to Evolution:
Patterns Of Change
Species with ________
SHORT reproductive cycles
MANY offspring tend to
that produce ________
quickly than species with
evolve more ________
LONG life spans and ______
FEW
_________
offspring.
Types:
steadily
a) Gradualism – evolution occurs _________
through time (Slow & Continuous) .
b) Punctuated Equilibrium- species stay the
same for long periods of time and then
change _______.
rapidly
Examples of Natural Selection
 Industrial
Melanism
 Antibiotic / Pesticide Resistance
Antibiotic Resistance
Ex: Punctuated Equlibrium
When bacteria are exposed to an antibiotic
there is a chance that a few will have a gene
that makes themRESISTANT
____________.
 The bacteria WITHOUT
___________ the resistance
will be killed, while those that are
RESISTANT
survive and pass on their
__________ will ________
genes for antibiotic resistance.

The antibiotic is the selecting agent
Resistant
Bacteria
Antibiotic X
Why should we be concerned about
antibiotic overuse?
Why does evolution matter now?
http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html
Pesticide Resistance
Insect A- Has resistance to A
Insect B- Has resistance to B
Insect C- Has resistance to C
What would happen to the population if
insecticide A were sprayed on the
field?
The pesticide selected
only those flies that
were __________
resistant to
pesticide A to survive.
In other words, some
insects had a
__________
MUTATION that allowed
them to survive the
presence of the
insecticide. These
insects were then able
to ___________
reproduce and
pass their _________
mutation
into the next generation.
Extinction


disappearance of an entire species (ex.
The ______________
Dinosaurs)
It can be caused by
temperature changes, pollution, or
_______________________________________
landscape changes
___________________