1. EQ: What are the types of isolation that lead to speciation?

2. TYPES OF ISOLATION Reproductive isolating mechanisms
Prezygotic isolating mechanisms
Geographic isolation
Ecological isolation
Behavioral isolation
Temporal isolation
Mechanical isolation
Prevention of gamete fusion
Reproductive isolation
Postzygotic isolating mechanisms
Hybrid inviability or infertility

3. Geographic isolation- involves physical barriers that divide a population into two or more groups
Isthmus of Panama formed 3 million years ago
Ex: snapping shrimp on each side will not mate with one another they snap at each other instead

4. Grand Canyon speciation of squirrels due to geographic isolation

5. Populations can become isolated in several ways.
Behavioral isolation- is caused by differences in courtship or mating behaviors
Changes in chemical scents, mating dances, songs or signals can prevent mating
Ex: Fireflies produce patterns of flashes that attract their mates. Over 2000 species of FF are isolated based on the patterns of flashes

6. Ecological isolation
Ecological isolation. Individuals mate in their preferred habitat, and therefore do not meet individuals of other species with different ecological preferences.

7. Behavioral isolation
Blue-fotted boobies select mates after an elaborate courtship display
Will not mate with other boobies

8. Temporal isolation- when timing prevents mating/reproduction between populations
Ex: The Monterey Pine and the Bishop pine have different pollination periods. (February/April)
Bishop pine

9. Field crickets’ reproductive isolation due to temporal isolation

10. Mechanical isolation
Structure of the male and female copulatory organs may be incompatible
Bees may carry the pollen of one species on a certain place on their bodies; if this area does not come into contact with the receptive structures of the flowers of another plant species, the pollen is not transferred

11. Prevention of gamete fusion
In animals that shed gametes directly into water, the eggs and sperm derived from different species may not attract or fuse with one another
In plants, the growth of pollen tubes may be impeded in hybrids between different species

12. Reproductive isolation occurs when members of different populations can no longer mate successfully with one another
It is the final step of becoming separate species

13. ♀ ♂ Hybrid inviability or infertility sterile x =
Male donkey crossed with female horse = sterile mule.
Male horse crossed with female mule = sterile hinny.
sterile