1. 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.
Spur
How might natural selection bring about the evolution of this orchid and the moth?

2. KEY CONCEPT Evolution occurs in patterns.

3. REMEMBER: Evolution through natural selection is not random.
Natural selection can have direction.
The effects of natural selection add up over time.

4. The 3 patterns we’re going to discuss today are:
Coevolution
Convergent Evolution
Divergent Evolution
We’ll also look at how these might be seen in the fossil record 

5. Coevolution

6. 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.

7. Coevolution Species A evolves an adaptation in response to species B
Species B evolves in response to the adaptation of species A

8. Coevolution can occur with species that help or compete with each other

9. The Star Orchid
and the
Hawk Moth

10. 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
Discussion Questions:
How does the flower benefit from looking like the female wasp?
 The flower benefits because the male wasp lands on the flower expecting to mate and is covered in pollen. It then flies to another flower that looks like a female wasp and pollinates the plant.
Predict what would happen to the flower if the appearance of the female wasp began to change?
If the female wasp began to change in appearance so would the flower. Flowers that looked more like the changing female wasp would be pollinated, while those that did not look like the female wouldn’t. This would cause the flower population to look more like the female wasp.

11. Convergent Evolution

12. 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

13. Divergent Evolution

14. Divergent evolution describes evolution toward different traits in closely related species. Divergent evolution can lead to speciation.
kit fox
red fox
ancestor

15. Changes in the frequency of a gene in the gene pool initially leads to microevolution. Microevolution refers to a small change in a population over a short amount of time. Many small changes eventually lead to macroevolution. Macroevolution refers to the sum total of many changes that transform organisms over a long period of time. Macroevolution leads to speciation or the creation of a new species. When an evolving population can no longer interbreed with the original population, a new species is formed.

18. 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?

19. WHICH PATTERN IS IT? divergent evolution
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

20. coevolution 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

21. Convergent evolution 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

22. Adaptive radiation OR divergent evolution
WHICH PATTERN IS IT?
coevolution convergent evolution divergent evolution
Beaver
NORTH AMERICA
Muskrat
Capybara
SOUTH AMERICA
Coypu
Beaver and Muskrat
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.
Adaptive radiation OR divergent evolution
BIOLOGY by Miller and Levine Pearson Publishing

23. divergent evolution 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