1. 1 Review What is geographic isolation Predict A newly formed lake divides a population of beetle species into two groups. What other factors besides isolation might lead to the two groups becoming separate species 2 Review What types of reproductive isolation may have been important in Galapagos finch speciation- explain Apply Concepts Explain how the vegetarian tree finch. Which feeds on fruit might have evolved

2. Ch 17 Evolution of Populations
17.3 The Process of Speciation

3. How does one species become two?

4. Speciation Formation of a new species
Species- group of organisms that are similar enough to mate and to produce fertile offspring.

5. Speciation Steps Part of population breaks off and becomes separated
Barrier prevents two groups from coming in contact with each other
Groups adapt separately to their own environments
Adaptations occur and add up until the two groups become different enough where even if barrier is removed the groups do not interbreed.

6. Lion and Tiger

7. Polar Bear and Grizzly Bear

8. Reproductive Isolation
Inability of one group to mate successfully with any other group.

9. Behavioral Isolation
Two populations that are capable of interbreeding develop differences in courtship rituals or other behaviors.

10. Geographic Isolation
Two populations are separated by geographic barriers such as rivers, mountains, or bodies of water.

11. Temporal Isolation
Two or more species reproduce at different times.

12. Speciation in Darwin’s Finches
Founding of a new population
Geographic isolation
Changes in the new population’s gene pool
Behavioral isolation
Ecological competition.

13. Founders Arrive
Many years ago a few finches (species M) arrived from South America.

14. Geographic Isolation The island had a unique environment
Founder effect, geographic isolation, and natural selection resulted in a new species
Species A.

15. Changes in Gene Pools
Populations on each island adapted to local environments
Two distinct populations evolved A and B.

16. Behavioral Isolation Some species B finches go back to first island
Enough time has passed where the two species remain isolated
Sexual selection keep them from mating.

17. Competition and Continued Evolution
Species evolve in a way that increases the differences between them, and new species may evolve C, D, and E
More specialized birds have less competition for food.