1. GENETIC CHANGE IN A POPULATION OVER TIME
EVOLUTION IS
GENETIC CHANGE IN A POPULATION OVER TIME
Population Dynamics
POPULATIONS IN ECOSYSTEMS

2. Types of evidence of evolution
Fossils
Homologies
Anatomical
Molecular
Developmental
Biogeography
Observable Events

3. Fossil Record Helps scientists understand pathway of evolution
Paleontology
Fossil
Remains: ex. bone, tooth, or shell
Traces: ex. burrow, footprint, or imprint
Photos by cbray

4. Fossil Record Most fossils are found in layered sedimentary rock
Oldest fossils are in the lowest layer
Newest fossils are in the top layer

5. Fossil Record Comparing fossils from different layers shows:
Life on Earth has changes
Increased number of life forms

6. Reduction of toes over time
Fossil evidence
Reduction of toes over time

7. Anatomical Homologies
Homologous Structures: Similar structure but different function
Shows:
Similar genes
Common ancestor
Turtle
Alligator
Bird
Mammal

8. Anatomical Homologies
Vestigial Structure: Body part reduced in function in a living organism but may have been used in an ancestor
Shows: Organisms evolutionary past
Whale pelvis & tailbone humans

9. Developmental Homologies
Shows:
Similar genes
Common ancestor

10. Developmental Homologies
Fish, reptiles, birds, & mammals (yes, even us!) all have a tail, limb buds & pharyngeal pouches in the early stages of development

11. Molecular Homologies DNA & the genetic code
DNA codes for amino acids proteins
“Universal” Genetic code
The similarity in DNA shows:
A probable common ancestor for all life on Earth
Genetic code table by cbray

12. Number of differences from human hemoglobin
Molecular Homologies
The amino acid sequence in a particular protein is compared between organisms. 8
125 45 27
Amino acid differences designed by cbray (with PPT clip art) 67 1
Number of differences from human hemoglobin

13. Amino Acid Difference in Hemoglobin Compared with Human
Molecular Homologies
Comparing amino acid sequence shows:
Closeness of relationship
A probable common ancestor
Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms.
Amino Acid Difference in Hemoglobin Compared with Human
Species
Difference
Gorilla 1
Rhesus Monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey
125
Amino acid differences chart by lpriddy
Human hemoglobin has 146 amino acids

14. Molecular Homologies
Amino Acid Difference in Hemoglobin Compared with Human
Species
Difference
Gorilla 1
Monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey
125
CLADOGRAM: diagram that shows the evolutionary relationship among a group of organisms. B A C D
Number of Amino Acid Differences
150
100 50 40 20 30 10
What organism belongs at each branch?
Where would the common ancestor be? E F
Amino acid differences chart by lpriddy G
Common ancestor

15. Biogeography Geographic distribution
organisms living far apart may be similar because they share a common ancestor

17. Observable Events
Some changes in species have been observed and studied
Shows: Evolution is an ongoing process
Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches
H. Kettlewell’s Study of Peppered Moth Color Shifts

18. Tempo of Evolution