1. Evolution and Speciation

2. Gene Flow
Gene flow- allele frequencies are changed by organisms migrating in and out of populations

3. Genetic Drift
Genetic drift- chance events that change allele frequencies (2 types)
Bottle Neck affect- a sudden random event in the environment can cause the population size to drop

4. Genetic Drift
Founder affect- a small portion of the populations is isolated and starts a new gene pool

5. Mutations
Mutations- random changes in DNA can change allele frequencies**

6. Speciation -speciation- the evolution of a new species
-species- organisms capable of interbreeding and producing healthy, fertile offspring

7. Speciation Categories
Allopatric Speciation- speciation due to geographic isolation (most common)
Sympatric Speciation- despite living in the same geographic area

8. Speciation
-geographic isolation- when a physical barrier divides a population, creating a new species.
(ex. Lava, earthquakes, etc)

9. Speciation
Reduced Hybrid Fertility- Two species can mate, but offspring are not capable of reproduction. (sterile)

10. Speciation
Behavioral Isolation- behaviors such as different courtship rituals prevent two species from mating

11. Speciation
-mechanical isolation- morphological differences prevent species from reproducing

12. Speciation
Temporal Isolation- The time line of breeding prevents species from mating. They mate during different times of day or seasons.

13. Speciation
Gametic Isolation – Incompatible gametes prevent two species from mating. (internal conditions vary, or gamete proteins don’t recognize one another)

14. Speciation
Reduced Hybrid Viability- Two species can mate, but offspring are not healthy and die.

15. Speciation
Hybrid Breakdown- Two species can mate, but when the Hybrids have offspring, the offspring are either sterile or unhealthy ( no grandkids)

16. Patterns of evolution Gradualism- evolution happens slowly over time
Punctuated equilibrium- evolution happens in quick bursts with long periods of no evolution in between.

17. Patterns of Evolution
Divergent evolution -(adaptive radiation)- species with a common ancestor become increasingly different (homologous)

18. Patterns of Evolution
Convergent evolution- unrelated species become similar (analogous)

19. Patterns of Evolution
Co-evolution- species evolve in response to each other