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Bellwork: Read the information below and follow the directions as given.
Spur
Imagine that you are traveling in
Madagascar when you find the flower to
the left. You see that it has a large spur
containing nectar in the tip. You
remember learning in science class that
some moths feed on nectar. Draw a
picture of what you think a moth
would look like that feeds on this
plant.Now answer this question:
How do you think natural selection
could help the flower and the moth
evolve together?
HOMEWORK TONIGHT!
• Watch the video “Cladograms” by Bozeman Science.
• http://www.youtube.com/watch?v=ouZ9zEkxGWg• Complete the homework page you picked up
on the way in.• Bring your homework to class tomorrow!
CO: I will evaluate and analyze mechanisms and patterns of evolution.
LO: I will take notes about evolution, and discuss scenarios with my group.
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. Coevolution2. Convergent Evolution3. Divergent Evolution
– We’ll also look at how these might be seen in the fossil record
• 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.
1. Co-evolution
Species A evolves an adaptation in response to
species B
Species B evolves in response to the adaptation
of species A
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 is unaffected.
Example: Orchid flowers that mimic female wasps
Mimicry is another example of coevolution
• 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
2. Convergent Evolution
• Divergent evolution describes evolution toward different traits in closely related species.
• Divergent evolution can lead to speciation.
kit fox
ancestor
red fox
Speciation: creation of 2 different species from 1 original species
Macroevolution: total of many changes that transform organisms over a long period of time.
Microevolution: small changes over a period of time
Changes in the frequency of a gene in a gene pool
leads to
leads to
leads to
Things to Consider:• Stasis - The organisms in the fossil record look 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?
So what about the fossil record?
WHICH PATTERN IS IT? coevolution convergent evolution divergent
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
http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T014608A.gif
WHICH PATTERN IS IT? coevolution convergent evolution divergent
evolution
coevolution
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 forthe hummingbird to pick up pollen as it feeds.
WHICH PATTERN IS IT? coevolution convergent evolution divergent
evolution
convergent 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)
WHICH PATTERN IS IT? coevolution convergent evolution divergent
evolution
divergent evolution
Beaver in North America and capybara in South America are closely related species living in very differentenvironments that have evolved to look differentover time.
Beaver
NORTH AMERICA
Muskrat
CapybaraSOUTH AMERICA
Coypu
Beaver
Muskrat
Beaver andMuskrat
Coypu
BIOLOGY by Miller and Levine Pearson Publishing