1. Evidence for Evolution

2. 1. Fossil Record Age & Behavior patterns
Show changes in climate & geography
Shows evolution & adaptation
Problems: Incomplete fossils & Imperfectly preserved

3. 1. Fossil Record Shows evolution & adaptation
Problems: Incomplete fossils & Imperfectly preserved

4. What similarities do you see among the forelimbs of these animals?
If you said “yes” then you just made a type of observation that scientists use to establish evolutionary relationships among organisms.

5. Homologous structures – similar internal structure found in different groups of organisms

6. Homologous structures
May or may NOT look the same on the outside
May have a different function
Shows common ancestor
Ex. forelimbs of vertebrates

7. What is a similar feature of these 2 organisms?

8. Analogous Structures
Structures w/similar function, but different internal structure
Any body part that is similar in function but different in structure is an analogous structure.

9. Shows evolution
But NOT by a common ancestor
Ex: wings – bats, insects, & birds

10. 3. Vestigial Structures Structures/organs that are no longer used
May have been used by ancestor
Indicate a change has occurred

11. Examples
Ostrich wings
Human appendix
Cave fish eyes

12. 4. Embryology
Many different animals have the same organs when they are embryos
Ex: embryos of fish, reptiles, birds & mammals all have gills.
Suggests evolution from a common ancestor
zebrafish chicken dog human skunk

13. 5. Genetic Comparisons
Shows evolutionary relationships using DNA sequences
Ex. DNA sequence for ATP is the same for all living organisms
Ex. Homologous structures require similar DNA

14. Which 2 species are most similar? Least similar?

15. Evolutionary Diagrams
Phylogenic trees and Cladograms –
Diagrams that shows evolutionary relationships of organisms based on similarities and differences in their physical or genetic characteristics.

16. Common Ancestor