1. Evolution: the Evidence
Biology
Evolution: the Evidence

2. Do Now 3/21/16 List 2 pieces of evidence for evolution

3. Evolution: The Evidence
Fossil Record
Geographic Distribution
Similarities in Structure
Similarities in Development
Molecular Biology

4. Fossil Record
Fossils = preserved remains or markings left by organism that lived in the past
Found in sedimentary rock
Buildup of sand and silt over long period of time
Deposited by rivers and compress sediment below

5. Sink to bottom and are buried in sediment
Aquatic organism
Sink to bottom and are buried in sediment
Land organism
Swept into rivers, lakes or swamps
Others covered by dust, sand or volcanic ash

6. Rock layers Younger rock strata on top of older ones
Position of fossils with the layers determine relative age
Chronological record life’s remains

7. Fossil Record Provides evidence of Earth’s changing life
Oldest fossil evidence = chemical traces in rocks 3.8 billion years old
Prokaryotes (bacteria & archaebacterial) have been found in rocks 3.5 billion years old
Data fits with evidence that prokaryotes are the oldest life forms
Younger fossils record evidence of eukaryotic organisms

8. Fossils provide evidence to link past to present
Ex: Whales evolved from land-dwelling ancestors that had 4 limbs

9. Geographic Distribution
Darwin noted that there are similarities and differences among species located in different parts of the world
Suggests these organism evolved from common ancestor

10. Geographic distribution
Why do some species share similar characteristic to other species found in a different ecosystem
Why are there so many marsupials in Australia verses placental animals

11. Geographic distribution
Just as fossil records provide evidence to the past Geographic distribution provides clues to how organisms may have evolved

12. Similarities in Structure
Similarities in structure among species provide clues to evolutionary history
Forelimb of mammals consist of same skeletal parts
Same parts but different functions
Called homologous structures

13. Homologous structures
Homologous structures = similar structures in species that share a common ancestor

14. Homologous structures
Homologous structures provide evidence that evolution is a remodeling process
Structures that functioned one way in an ancestral species changes over time as it takes on new functions
Darwin called this “descent with modification”

15. Vestigial structures Vestigial structures
Are remnants of structures that may have had important functions in ancestral species but no clear function today’s species
Goosebumps
Dewclaws in dogs and cats
Appendix

16. Vestigial structures

17. Vestigial structure of Human

18. Similarities in Development
Development of organisms and the similarities provide clues to evolutionary history
Embryos of similar closely related organisms have similar stages of development
Supports homologous structures

19. embryology

20. Molecular Biology DNA sequencing
Reading genetic codes enable closer comparison of organism
The more similarities or matches the closer the organisms are related
The more differences among the DNA sequence the less related and less likely they share a common ancestor

21. Molecular biology

23. Evidence for Evolution
Molecular Biology
Similariities in Develop-ment
Evidence for Evolution
Similariities of Structure
Geographic distribution
Fossil Record