Download Parallel Evolution = when species develop from common ancestor

Goal 3.05d: Applications of Evolution
through Natural Selection
The process through which natural selection occurs
varies according to
the environment and the organisms involved.
Divergent Evolution = when species develop from a
common ancestor
evolutionarymodel.com
Convergent Evolution = when species develop similar
traits but are not evolutionarily connected.
pbs.org
Parallel Evolution = when species develop from
common ancestor along a parallel path without
diverging.
biologie.uni-hamburg.de
Coevolution = a change in the genetic composition of
one species (or group) in response to a genetic change
in another.
sdakotabirds.com
Three Types of Natural Selection
Stabilizing Selection = maintains an already existing system.
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>
>
>
eliminates organisms that deviate from the norm.
environment must remain unchanged.
explains why there are “living fossils.”
as long as environment doesn’t change, organisms
won’t change.
Ginkgo Tree
Horseshoe Crab
Directional Selection = favors one extreme or the other.
> eliminates organisms that are not in that extreme.
> eventually leads to changes in the population.
> occurs when organisms must adapt to a change in
their environment.
> may develop into a RESISTANCE (the ability of an
organism to withstand a harmful agent).
MALARIA
Directional Selection: PESTICIDE Resistance
Pesticide = kills insects (pests)
Insects with resistance live to reproduce…
Resulting in a new population of resistant insects.
This insect was not.
This insect was born with resistance.
• Malaria is a bacteria transported by mosquitoes.
• DDT (toxic pesticide) was used to kill mosquitoes.
• India 1959 DDT-resistant mosquitoes were
detected.
• When directional selection occurs, the resistant
mosquitoes survive to produce a new resistant
population.
Resistance is amplified by directional selection.
• The directional selection of malaria has led to a
change in the gene pool of persons living in malariainfested areas.
• Sickle-cell anemia is a disease of the blood in which
the hemoglobin does not develop properly and the
red blood cell is sickle-shaped.
• HEMOGLOBIN is the part of the red blood cell that
carries oxygen throughout the body.
Directional Selection: ANTIBIOTIC Resistance
Normal
Antibiotics = kill bacteria
Resistant
Some bacteria are
naturally resistant to
antibiotics and must be
killed by your body.
Your
Your doctor
doctor gives
gives you
you
antibiotics
antibiotics to
to help
help your
your
body
body kill
kill the
the normal
normal
bacteria.
bacteria. This
This allows
allows your
your
body
body to
to concentrate
concentrate on
on
the
the RESISTANT
RESISTANT bacteria.
bacteria.
Directional Selection and the Peppered Moth.
> Before industrial revolution = moths are peppered.
> After industrial revolution = moths are black.
> After pollution controls = moths are peppered.
Disruptive Selection = favors two extremes at one time.
> eliminates organisms that are more common.
> eventually leads to changes in the population.
African butterflies can
range from red to blue.
The red and blues are
foul-tasting to predators.
The other colors are
eaten more often
resulting in a selection in
favor of the extreme
colors.