1. Speciation and Extinction
Big Idea 1: The process of Evolution drives the diversity and unity of life

2. 1C3: Populations in nature continue to evolve.
Essential Knowledge
1C1: Speciation and extinction have occurred throughout the Earth’s history.
1C2: Speciation may occur when two populations become reproductively isolated from each other.
1C3: Populations in nature continue to evolve.

3. Species
A group of individuals capable of interbreeding and exchanging genetic info to produce viable, fertile offspring.
YES Panda Babies!
NO Dog-Cat Babies!

4. Speciation Creation of a new species
Usually occurs when 2 pops diverge from a common ancestor

5. Speciation Can Be Slow….
Very gradually, over a long time, the population changes (gradualism). Change is slow, constant, and consistent (Darwin).

6. Speciation Can Be Fast…
Bursts of change followed by quiet periods (Punctuated Equilibrium, Eldredge and Gould, 1972)

7. What Could Cause Bursts??
Sudden, quick changes in the environment leads to more available niches!

8. Speciation is the reason for diversity of life!

9. Geographic Isolation
Separation of pops by a geographic barrier exposes species to new environmental conditions.

10. TPS: What Other Items May Be Geographic Barriers?

12. Reproductive Isolation
Biological factors (barriers) that stop 2 species from producing viable, fertile offspring
Can be pre/post zygotic barriers

13. Example: Polyploidy More than 1 set of chromosomes.
Ex: Wheat: strains that are diploid (2 sets), tetraploid (4 sets) durum or macaroni wheat, hexaploid (6 sets) bread wheat. 
Will not interbreed with each other.
Done through human hybridization and selection…sometimes made in nature thanks to meiosis mistakes..nondisjunction.

14. Prezygotic Barriers Goal: To impede mating/fertilization!
Blue Footed Booby Dance
Goal: To impede mating/fertilization!
Habitat isolation: no/rare contact
Temporal isolation: mate at diff. times of yr.
Behavioral isolation: behavior mating rituals.
Mechanical isolation: Morphological differences

15. What Kind of Prezygotic Barrier is This?

16. Goal: Prevent a hybrid zygote from being a viable adult
Postzygotic Barriers
Goal: Prevent a hybrid zygote from being a viable adult
Frail/Weak Hybrids
Sterile Hybrids

18. Occurs rapidly at times of ecological stress.
Extinction
Occurs rapidly at times of ecological stress.

19. Habitat Loss/ Habitat Fragmentation

20. Hunting/Poaching

24. Overfishing

25. 5 Major Mass Extinctions
Then why is there 6??? What is that 6th one?

26. On a Positive Note..
Extinction opens up available niches (jobs) and leads to new species creation.

27. Evolution Continues to Occur…
Activity in class…