1. The Process of Speciation
Unit 16 Part 2
The Process of Speciation

2. Introduction Speciation is the formation of new species
Different species can not interbreed to produce fertile offspring.
Individuals in different species have a different gene pool.

3. Reproductive isolation:
When members of the two different species do not interbreed and produce fertile offspring.
Populations must be reproductively isolated from each other for a new species to evolve.
Three ways that reproductive isolation occurs.
1. Behavioral isolation
2. Temporal isolation
3. Geographic isolation

4. Behavioral isolation
occurs when populations are capable of interbreeding BUT have differences in courtship rituals or other types of behavior.
Example: Eastern and Western meadowlarks
-Their regions overlap
-They can interbreed but do not
-Different courtship rituals (attracted by different songs)

5. Geographic isolation - can occur when populations are separated by geographic barriers such as rivers, mountains, or bodies of water.
Example: -The Kaibab squirrel evolved from the Abert squirrel when it was isolated from the main population by the Colorado River.
Kaibab
Abert

6. Temporal Isolation
Occurs when two or more species reproduce at different times.
Example: three similar species of orchid in the same rain forest releases pollen on different days.

7. Testing Natural Selection in Nature
How could differences in beak size lead to reproductive isolation?
Birds with the same beak size prefer to mate with each other.
Since, big-beaked and smaller-beaked birds would not choose to mate with each other, their gene pools would remain isolated.
Studying Evolution Since Darwin
Why is the study of evolution important in the scientific world?
By understanding evolutionary theory, we have been able to respond to changes in the living world in ways that have improved human life.