1. Origins Of Biological Diversity
Chapter 15

2. Species
A population or group of populations whose members have the ability to breed with one another and produce fertile offspring

3. Macroevolution
Dramatic biological changes that include the origin of different species
Diversity Increases

4. Speciation The formation of new species
For new species to form there must be a barrier between the same species to make the group genetically isolated.

5. Kaibab squirrel Abert squirrel
Speciation
Kaibab squirrel Abert squirrel

6. Genetic Isolation
Reproductive Barriers
Geographic barriers

7. Reproductive Barriers
Prevents closely related species from interbreeding
Timing
Behavior
Habitat

8. Timing Similar species have different breeding seasons
Eastern Spotted Western Spotted
Skunk Skunk

9. Behavior
Similar species may have different courtship or mating behaviors.
Ex: Eastern & Western meadowlarks almost identical in color shape & habitat, but difference in courtship rituals differ different species

10. Habitat
Species remain reproductively isolated because they are adapted to different habitats.
Ex: Stickleback fish one is a bottom feeder, one spends time in the top open layers of lakes in British Columbia, Canada

11. Geographic barriers
A physical barrier that separates a population into groups.
Can be
Mountains
Islands with water in between Darwin’s 13 finches on Galapagos
Valleys caused by lava flow

12. Mountains

13. Geographical isolation

14. Patterns of Evolution
Divergent Evolution
Convergent

15. Divergent Evolution
Related organisms become less alike through Adaptive Radiation
Ex: Galapagos Finches common ancestor on the main land blown to different islands naturally selected into a new species

16. Darwin’s Finches

18. Convergent Evolution
Unrelated species resemble each other due to adaptation to similar environments
Environment has an important selective effect on the evolution of species

19. A Hummingbird Moth
A Humming Bird

20. Rate of Evolution Evolution occurs very slowly Gradualism
Punctuated Equilibrium

21. Gradualism Gradual changes in species over time
Evidence of many intermediate forms in fossil records

22. Punctuated Equilibrium
Scientists found remains of intermediate forms but also saw that populations remained the same over large periods of time then suddenly changed