Download WHICH PATTERN IS IT?

Bellwork
Imagine that you are traveling in
Madagascar when you find the plant to the
left. You see that the plant has an
unusually large spur containing nectar in its
tip. You remember learning in science class
that some moths feed on nectar. Draw a
picture of what you think a moth may look
like that feeds on this plant.
How might natural selection bring about the
evolution of this orchid and the moth?
Today’s WHAT:
I will evaluate and analyze
mechanisms and patterns of
evolution.
Today’s HOW:
I will write notes. I will read and
discuss scenarios with a partner.
KEY CONCEPT
Evolution occurs in patterns.
REMEMBER: Evolution through natural selection is
not random.
• Natural selection can have direction.
• The effects of natural selection add up over time.
The 3 patterns we’re going to discuss
today are:
1. Coevolution
2. Convergent Evolution
3. Divergent Evolution
– We’ll also look at how these might be seen in the
fossil record 
Coevolution
Co-evolution
•
•
•
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
Coevolution can occur with species
that help or compete with each other
The Star Orchid
and the
Hawk Moth
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
Changes in the frequency of a gene in a gene pool
leads to
Microevolution: small change over a period of time
leads to
Macroevolution: total of many changes that transform
organisms over a long period of time.
leads to
Speciation: creation of 2 different species from 1 original
species
How does this affect the fossil
record??
So what about the fossil record…
Things to Consider:
• Stasis - The organisms in the fossil record looks the
same from when they appear to when they
disappear;
• Sudden appearance - When a species does not arise
by gradually changing steadily from its ancestors; it
appears all at once and fully formed.
• Sequential nature – Based on the layers of rock, we
sequence organisms in the fossil record.
• What might cause stasis or sudden appearance?
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
divergent evolution
Beaver
Beaver
NORTH
AMERICA
Muskrat
Muskrat
Beaver
and
Muskrat
Capybara
SOUTH AMERICA
Coypu
Coypu
divergent evolution
BIOLOGY by Miller and Levine Pearson Publishing
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