Reading 16-3 : The Process of Speciation

1. Define species: _______________________________________________________________________
2. As new species evolve, populations become reproductively ________________________ from each other.
3. What sops an eastern meadowlark from breeding with a western meadowlark? ______________________
4. Give an example (or description) of geographic isolation: _______________________________________
5. What are the two squirrel species that exist on opposite sides of the Colorado river and what is their color?
Squirrel 1 ________________________________ color: ___________________________
Squirrel 2 ________________________________ color: ___________________________
6. When two species cannot reproduce at the same time, it is called _______________________ isolation.
7. Examine Figure 16-3 and identify what each of the following finches eats:

Testing Natural Selection in Nature

8. Once Darwin discovered that the birds were all finches, he hypothesized that they descended from a
______________________ _______________________
9. Darwin's hypothesis relied on two testable assumptions:
1) There must be heritable __________________________ in those traits
2) Differences in shape must produce differences in ________________________

Peter and Rosemary Grant tested the hypothesis. Complete each statement about their observations.
10. The Grants measured and [ identified / tagged ] as many birds as possible.
11. They recorded which birds [ died / migrated ] and which succeeded in breeding.
12. The purpose of measuring the birds was to show that they have
[fitness / variation]
13. During a [ season / drought ], differences in beak size can mean the difference between life and death.
14. A feeding [ generalist / specialist ] is a type of bird that chooses food based on what its beak handles best.
16. Finches with [ large / small ] beaks were most likely to survive.
17. The next generation of finches had [ larger / smaller ] beaks.

Speciation in Darwin's Finches

19. Where did the first finches on the islands come from? _____________________________________
These first finches were called ____________________________________
20. Over time, populations on the island became ________________________ to their local environments.
21. How do finches choose their mates? __________________________________________
22. Most specialized birds have less __________________________________________ for food.
23. How many different finch species can be found on the Galapagos? ________________

Studying Evolution Since Darwin

24. New data from what three scientific fields supports the theory of evolution by natural selection?
______________________ _______________________ ____________________________
25. The Grants observed changes in beak size, but they didn't actually see what? _____________________
26. Define SCIENTIFIC THEORY: ___________________________________________________________