1. Outline 16-3: The Process of Speciation
4/24/2019

2. The formation of a new species
What is speciation?
The formation of a new species
4/24/2019

3. 4/24/2019
I. Speciation
A. Formation of new species 1. A species is a group of organisms that breed with one another and produce fertile offspring. 2. The gene pools of two populations of a species must become separated for them to become new species.
4/24/2019

4. The Process of Speciation
What does it mean for two species to be reproductively isolated from each other?
Members of the two species cannot interbreed and produce fertile offspring.

5. They will have separate gene pools.
4/24/2019
3. As new species evolve, two populations can become so different from each other that the populations eventually become reproductively isolated from each other
a. When members of two populations cannot interbreed & produce fertile offspring, reproductive isolation has occurred.
They will have separate gene pools.

6. The Process of Speciation
List three ways that reproductive isolation occurs.
Behavioral isolation
Temporal isolation
Geographic isolation

7. Be ready to discuss each type of isolation
I will be pulling a card!
Behavioral isolation
Temporal isolation
Geographic isolation
4/24/2019

8. a. Behavioral Isolation
4/24/2019
4. Reproductive isolation can develop in a variety of ways:
a. Behavioral Isolation
Organisms are capable of inter breeding but have differences in courtship rituals or other reproductive strategies.
Examples:
Meadowlarks, blue-footed boobies, albatross, firefly flash patterns
4/24/2019

9. Eastern & Western Meadowlarks have different mating songs
4/24/2019
Song
Song
Eastern & Western Meadowlarks have different mating songs
Blue-footed boobies have specific courtship rituals

10. Firefly flash patterns
4/24/2019

11. 4/24/2019
b. Geographic Isolation Two populations are separated by geographic barriers such as rivers or mountains & thus can’t interbreed Examples: Kaibab & Abert squirrels Wrasse fishes
4/24/2019

12. 4/24/2019
Grand Canyon

13. Kaibab squirrel Abert’s squirrel
4/24/2019
Kaibab squirrel Abert’s squirrel

14. 4/24/2019
c. Temporal Isolation Occurs when two or more species reproduce at different times. Examples: Wood & leopard frogs mate at different times; orchids release pollen on different days
4/24/2019

15. Amphibian temporal isolation
4/24/2019

16. Orchid temporal isolation
4/24/2019
Orchid temporal isolation
Release pollen on different days

17. The Process of Speciation
Is the following sentence true or false?
Eastern and Western meadowlarks are an example of behavioral isolation.
True

18. The Process of Speciation
Fill in the blank:
Abert and Kaibab squirrels in the Southwest are an example of _______ isolation.
geographic

19. Testing Natural Selection in Nature
Is the following sentence true or false?
The basic mechanisms of evolutionary change cannot be observed in nature.
false

20. Testing Natural Selection in Nature
Studies showing natural selection in action involve descendants of the finches that Darwin observed in the Galápagos Islands.
The finches Darwin saw were different, but he hypothesized that they had descended from a common ancestor.
Copyright Pearson Prentice Hall

21. II. Natural Selection in Darwin’s finches
4/24/2019
II. Natural Selection in Darwin’s finches
Detailed genetic studies have shown that these finches evolved from a species with a more-or-less general-purpose beak. 

22. 4/24/2019

23.  Beaks became larger & more massive at such times
4/24/2019
A. Studied by Peter & Rosemary Grant ( )
1. Results of Study:
a. During wet years, when food is plentiful, bird beak size doesn’t matter much (All beaks work on plentiful small, soft seeds)
b. During dry years, plants make fewer seeds & more of them are larger and harder to open
 Beaks became larger & more massive at such times

24. 4/24/2019

25. III. Speciation in Darwin’s Finches
4/24/2019
III. Speciation in Darwin’s Finches
A. Speciation of Darwin’s finches is an example of adaptive radiation.
1. Single species evolves into several different ones
B. Occurred by
1. founding of a new population
2. geographic isolation
3. changes in new population's gene pool
4. reproductive isolation
5. ecological competition
4/24/2019

26. Complete the flowchart to show how speciation probably occurred in the Galápagos finches.

27. Speciation in Darwin's Finches
4/24/2019
Founders Arrive 
A few finches —species A—travel from South America to one of the Galápagos Islands.
There, they survive and reproduce.
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species.

28. Speciation in Darwin's Finches
4/24/2019
Speciation in Darwin's Finches
Geographic Isolation
Some birds from species A cross to a second island.
The two populations no longer share a gene pool.
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species.

29. Speciation in Darwin's Finches
4/24/2019
Changes in the Gene Pool
Seed sizes on the second island favor birds with large beaks.
The population on the second island evolves into population B, with larger beaks.
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species.

30. Speciation in Darwin's Finches
4/24/2019
Reproductive Isolation
Population B birds cross back to first island. They will not mate with birds from Pop. A.
A & B are now separate species.
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species. B

31. Speciation in Darwin's Finches
4/24/2019
Ecological Competition
Species A & B compete for seeds on first island & continue to evolve differences.
New species - C - may evolve.
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species. B C

32. Speciation in Darwin's Finches
4/24/2019
Continued Evolution
These processes continue across the entire Galapagos island chain until 13 species evolved. G D E
Speciation in the Galápagos finches occurred by founding of new populations, geographic isolation, gene pool changes, reproductive isolation, and ecological competition. Small groups of finches moved from one island to another, became reproductively isolated, and evolved into new species. B F C