1. Bellringer
What is genetic drift? What are two mechanisms (ways it is caused) of genetic drift?
Once done answering the bellringer question on your sheet, please add questions (2 per page) and a summary to your Darwin and Natural Selection Notes.
Summary
3 things you learned
2 things you found interesting
1 question you still have

2. Evidence for Evolution

3. Learning Targets
Explain three ways natural selection can change the distribution of a change in a population
Explain the evidence for evolution with regards to the fossil record, geographic distribution of organisms, anatomical structures, embryology, and molecular biology.
Be able to compare and contrast homologous, analogous, and vestigial structures.

4. Review of Natural Selection
Remember Darwin came up with the Theory of Evolution.
Natural selection leads to Descent with Modification – traits are passed down from generation to generation and sometimes undergo changes or modifications over time

5. Three ways natural selection can change the distribution of a population  
Disruptive

6. This is __________ Selection:
Favors phenotypes at one extreme of a trait’s range.
1. Directional

7. This is __________ Selection:
Intermediate phenotype favored and becomes more common in population
2. Stabilizing

8. This is __________ Selection:
Occurs when BOTH extreme phenotypes are favored, intermediate phenotypes selected against.
3. Disruptive

10. Evidence for Evolution
Evidence for Evolution
Fossil record
Shows change over time.
Fossils of extinct species provide evidence of shared ancestry and how organisms and the environment have changed over time.
Biogeography
Differences and similarities between organisms in different locations around the world.
Provides evidence of how modern species share a common ancestor but have evolved to fit environments in different locations.

11. Evidence for Evolution
Anatomical strucures
comparing body structures, similarities and differences.
Molecular record
comparing protein & DNA sequences.
The greater the similarities in DNA and protein sequences, the more likely two organisms share a common ancestor.
Universal genetic code (ATGC) provides evidence that ALL life forms are related.

12. Evidence for Evolution
Embryology
comparison of stages of embryonic development between organisms of different species.
Embryos of closely related species have similar stages of development.

14. Anatomical Structures
Anatomical Structures
Homologous structures-structures that come from the same origin, but have different functions.
homo- = same
-logous = information
Forelimbs of human, cats, whales, & bats
same structure
on the inside
same development in embryo
different functions
on the outside
evidence of common ancestor
Divergent Evolution (similar ancestor, but due to isolated environments evolve to adapt best to environment)

15. Anatomical Structures
Anatomical Structures
Analogous structures:  structures that have a similar function but do NOT have similar internal structure.
look similar
on the outside
same function
different structure & development
on the inside
different origin
no evolutionary relationship
Convergent Evolution (similar living environments, adapted in similar way).

16. Convergent evolution (Analogous structures)
Convergent evolution (Analogous structures)
evolving similar solutions to similar problems
3 groups with wings
Does this mean they have a recent common ancestor?

17. Analogous or Homologous?
Dolphins: aquatic mammal
Fish: aquatic vertebrate
both adapted to life in the sea
not closely related

20. Anatomical Structures
Vestigial Structures: Remnants of structures that may have had important functions in an ancestral species but have no clear function in the modern species  shows common ancestry with adaptations to changing environments.

21. Discuss with a Partner What are the Main Evidences for Evolution?
Which do you feel is the strongest support of Natural Selection?
Why?