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Patterns of Evolution
Evolution Notes Part 3
• What is microevolution?
– Evolution on a small scale within a single
population
• Natural selection is a mechanism for
changes in populations that occurs when
organisms with favorable variations
survive, reproduce, and pass on traits to
the next generation.
• Artificial selection is the breeding of
certain traits over others.
Speciation
• What causes • Reproductive isolation – when
new species
populations are prevented in
to form?
some way from reproducing with
each other , their gene pools
adapt and evolve separately,
causing them to lose the ability
to cross breed
Reproductive Isolation
• What causes • Geographic isolation –
reproductive
mountains, rivers, canyons
isolation?
• Temporal isolation – active or
reproducing at different times of
day or times of year
• Behavioral isolation –
differences in mating rituals that
prevent reproduction between
groups
Anatomical
• Some adaptations involve changes in the
structure of body parts: mimicry and
camouflage.
– Mimicry enables an organism to copy the
appearance of another species.
MIMICRY
Anatomical
• Some adaptations involve changes in the
structure of body parts: mimicry and
camouflage.
– Camouflage is a structural adaptation that
enables an organism to blend in with its
surroundings.
CAMOUFLAGE
Physiological Adaptations
• Some adaptations are physiological or
changes in an organisms metabolic
processes.
– Keep in mind that all things are made up of
cells and the organelles are structurally and
functionally similar in most organisms.
Physiological Adaptations
• Organisms are constantly changing to
adapt to their environment. Take a look at
organisms that have been exposed to
antibiotic and pesticides. The organisms
that survive have become selected
because they are physiologically more
resistant.
Imagine that there are 10
bacteria growing on your
hand.
You use Germ-x to clean your
hand everyday.
After 4 days, there are still 3
bacteria on your hands that have
survived.
Is there anything special about
these bacteria?
Yes..they have something about
their DNA that has made them
different and strong enough to
survive.
So now what will happen?
Those 3 that are “resistant” will
undergo Mitosis.
And after a week, your hands will be
covered with tons of bacteria that
are ALL resistant to Germ-X. 
Macroevolution
• What is
• Large scale evolutionary
microevolution?
patterns and processes
occurring over long periods
• What is
of time
macroevolution?
• Transcends the boundaries
of a single species
Macroevolution
• What are the
1. Extinction
important topics 2. Adaptive radiation
in
3. Convergent evolution
macroevolution?
4. Coevolution
5. Punctuated equilibrium
6. Changes in developmental
genes
Extinction
• Why is
extinction
important?
• Several times in Earth’s
history, mass extinctions
wiped out ecosystems
– During these events, many
species became extinct
– Other species took advantage
of ecological opportunities as
habitats opened up
– This produced a burst of
evolution
Adaptive Radiation
• What is
adaptive
radiation?
• When a single species or
group of species evolve
through natural selection into
diverse forms that live in
different ways
Adaptive Radiation
• What are some • Darwin’s finches
examples?
• Wild mustard variations
Convergent Evolution
• What is
convergent
evolution?
• Unrelated organisms in
similar environments evolve
to look remarkably similar to
each other
• What are some • Similarities between
Australian marsupials and
examples?
placental mammals
• Similarity in form between
dolphins and sharks
Coevolution
• What is
coevolution?
• Two species evolve in
response to changes in each
other over time
• What are some • Plants develop pollination
methods that take advantage
examples?
of insect feeding adaptations,
and vice versa
Punctuated Equilibrium
• What is
punctuated
equilibrium?
• “Rapid” evolution after long
periods of equilibrium – often
occurs due to isolated
populations, migrations, or
mass extinctions
Developmental Genes
• What is meant
by changes in
developmental
genes?
• Homologous control genes
serve similar functions in
animals that have not shared
a common ancestor in
millions of years
What should I believe?
• Although evolution is widely accepted by scientists
and had broad supporting evidence, it is still a theory
• Remember, theories are well-supported testable
explanations of phenomena that have occurred in the
natural world
• There are differences of opinion about interpretation
and every person is entitled to his or her own opinion –
the experts are not always objective
• Our goal is to present the prevailing view and allow
you to reach your own conclusions
• Remember that everyone is entitled to their own
opinion – yours is no more right nor wrong than
anyone else’s