1. Evidence for Evolution
Evidence from dead organisms
Evidence from living organisms

2. Fossils – remains of dead organism
Recognizable evidence of ancient life
Fossilized hard parts (most common) ex. Bones, teeth, shells, spores, seeds etc
Traces of fossils (indirect evidence), footprints, leaf prints, tracks, burrows.

3. Fossilization Organism becomes buried in ash or sediments
Rapid burial and a lack of oxygen aid in preservation
The organic remains become infused with metal and mineral ions

4. What Do Fossils Tell Us?
As a result of mutations, natural selection, and drift, each species is a mosaic of ancestral and novel traits
All species that ever evolved are related to one another by way of descent
Differences and similarities between fossils and living

5. How old are the fossils? Radiometric Dating
parent isotope in
newly formed rock
after one half-lives
after two half-lives

6. Continental Drift

7. Evidence from Biogeography
Continental Drift
Idea that the continents were once joined and have since “drifted” apart
Initially based on the shapes
Pangea: theoretical supercontinent: Explains the worldwide distribution of more ancient life MYA
Laurasia and Gondwanaland: Explains why certain life forms exist in the northern land and some only in the southern lands MYA

8. Evidence from biogeography

9. Evidence from Living things Comparative Morphology
Comparing body forms and structures of major lineages
Guiding principle:
When it comes to introducing change in morphology, evolution tends to follow the path of least resistance

10. Morphological Divergence due to1 2 3
Morphological Divergence due to
Adaptive Radiation
PTEROSARUR 4 1 2
CHICKEN 3
Homologous structures: evolved from a common ancestor (so similar in structure) but has changed (different environmental pressures) to serve different functions
STEM REPTILE 2 3
PENGUIN 1 2 3 4 1 5 2
PORPOISE 4 3 5 1 2
BAT 3 4 5 1 2 3 4
HUMAN 5

11. Morphological convergence due to convergent evolution
Analogous structures
Evolved from different ancestors
But serves the same purpose
Different ancestry but similar function
Q: Which structures here show convergent evolution and which show divergent?

12. Vestigial structures
Body parts that had a function in the ancestor but not anymore
Evidence of descent from a ancestor that used those parts.
Ex. Pelvic bones in snakes
Human appendix etc.

13. Comparative Development
During development, each animal or plant proceeds through a series of changes in form
Similarities in these stages may be clues to evolutionary relationships
Mutations that disrupt a key stage of development are selected against

14. Comparative Development

15. Comparative Biochemistry
Kinds and numbers of biochemical traits that species share is a clue to how closely they are related
All life contains DNA, makes proteins using RNA and similar biochemical processes
More similarity means species are more closely related

16. Comparing Proteins
Compare amino acid sequence of proteins produced by the same gene
Human cytochrome c (a protein)
Identical amino acids in chimpanzee protein
Chicken protein differs by 18 amino acids
Yeast protein differs by 56

17. Speciation & Natural Selection
Natural selection can lead to speciation
Speciation can also occur as a result of other microevolutionary processes
Genetic drift
Mutation
“Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.” Ernst Mayr