Transcript Mechanisms of Evolution

 HAPPY WEDNESDAY 
Explain in 32 words what is
happening in this
PEDIGREE comparing
long-necked giraffes vs
short-necked giraffes.
Essential Question: How do
evolutionary mechanisms other than
natural selection affect adaptation and
diversity?
Standard 7F: Analyze and evaluate effects of
other evolutionary mechanisms.
It is widely accepted that the first living things
on Earth were prokaryotic cells (bacteria). How
did prokaryotic cells turn into eukaryotic ones?
The answer is The Endosymbiotic Theory.
K. The Endosymbiotic Theory is the theory that
eukaryotic cells formed from a symbiosis (two
organisms live together) among several
different prokaryotic organisms.
Co-evolution
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Sometimes organisms that are closely connected
to one another by ecological interactions evolve
together.
An evolutionary change in one organism may also
be followed by a corresponding change in
another organism.
The process by which two species evolve in
response to changes in each other over time is
called coevolution.
Coevolution can occur with species
that help or compete with each other
Mimicry is another example of
coevolution
• Mimicry occurs when one organism evolves to
look like the other in order to benefit itself.
The mimic benefits from the situation while the
organism it mimics in unaffected.
Example: Orchid flowers
that mimic female wasps
Convergent Evolution
Convergent Evolution
• Convergent evolution describes evolution toward similar
traits in unrelated species.
• When two species are similar in a particular characteristic,
it’s only convergent evolution if their ancestors were not
similar
Divergent Evolution
• Divergent evolution describes evolution
toward different traits in closely related
species.
• Divergent evolution can lead to speciation.
kit fox
red fox
ancestor
Scenarios
Mix-Freeze-Group
Genetic
Mutation
Natural
Selection
Small
Population
Non-Random
Mating
• I am going to survive! Because I have the best genes for my
environment.
• I am HUGELY affected by genetic drift.
• I am VERY picky. I will only choose you, because your traits
are most attractive to me.
• I am a mistake in the DNA sequence
1. Amish people are required by their religion to
only marry and have children with other
Amish people.
2. The DNA sequence in a bird is changed from
ATT CCG TTG to TTA CCG TTG which changes
the beak shape from long and thin to short
and fat.
3. Peppered moths are eaten by birds. The moth
color varies from light to dark. Light colored
moths can blend in with a nearby species of
tree. In the 1800s factories released large
amounts of soot, which changed the tree color,
so the birds were able to more easily find the
lighter moths instead of the darker moths.
4. Northern elephant seals were hunted almost
to extinction by people in the 1890s. The
remaining population has reduced genetic
variation.
5. A lioness joins a new pride and has cubs with
the male lion.
6. A small group of birds flies from the mainland
to an island and starts a new colony. (The
birds never return to the mainland.)
http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T014608A.gif
WHICH PATTERN IS IT?
coevolution
convergent evolution
divergent evolution
The Galápagos finches evolved through natural
selection from a common ancestor into a wide
variety of different looking species with different
kinds of beaks
divergent evolution
WHICH PATTERN IS IT?
coevolution
convergent evolution
divergent evolution
Hummingbirds have a beak just the right length
to reach the nectar in a cardinal flower and as
they feed their foreheads bump into the pollen
structure. Cardinal flowers are red which
hummingbirds can see, but bees can’t, and their
pollen structure is at just the right height for
the hummingbird to pick up pollen as it feeds.
coevolution
WHICH PATTERN IS IT?
coevolution
convergent evolution
divergent evolution
Whales, sharks, and penguins all have
streamlined
bodies and fins/flipper for moving in water
even though they belong in different animal
groups
(mammals, fish, and birds)
Convergent evolution
WHICH PATTERN IS IT?
coevolution
convergent evolution
Beaver
Beaver
NORTH
AMERICA
Muskrat
Muskrat
Beaver
and
Muskrat
Capybara
SOUTH AMERICA
Coypu
Coypu
divergent evolution
BIOLOGY by Miller and Levine Pearson Publishing
divergent evolution
Beaver in North
America and capybara
in South America are
closely related species
living in very different
environments that have
evolved to look
different
over time.
WHICH PATTERN IS IT?
coevolution
convergent evolution
divergent evolution
The tortoises on the Galapagos islands share
a
common ancestor, but over time they have
become
adapted for obtaining food in different habitats
on different islands by having different
neck lengths
divergent evolution