1. Evidences of Evolution

2. Genetic change in a population over time
Evolution
Genetic change in a population over time
Population Dynamics
POPULATIONS IN ECOSYSTEMS

3. Charles Darwin
On his journey around the world, Darwin found evidence of gradual change (evolution).
Darwin cited evidences he found in fossil records, homologous structures, and geographic distribution.

4. Evidences of Evolution
Today most evidences for evolution are grouped into five main categories:
Fossil Record
Biochemical
Comparative Anatomy
Biogeography
Observable Events

5. Fossil Record Paleontology- the study of fossils
Fossils – remains or traces of organisms that lived long ago
Remains: ex. bones, teeth, or shells
Traces: ex. burrows, footprints, or imprints
Photos by cbray

6. Most fossils are found in layered
Fossil Record
Most fossils are found in layered
sedimentary rock
Layers diagram by cbray
Oldest fossils are
on the lowest layer

7. Fossil Record The fossil record is incomplete
Some environments are less likely to cause fossil formation
Bodies of some organisms decay faster than others
The fossils that have formed present strong evidence that evolution has taken place
Relative and radiometric dating

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

9. Biochemical Evidence Universal Genetic Code
Triplets of DNA nitrogen-base sequences that code for specific amino acids
The similarity of triplet DNA codes making-up amino acids shows:
a probable common ancestor for all life on Earth
Genetic code table by cbray

10. Number of differences from human hemoglobin
Biochemical Evidence
Amino Acid Sequencing
The amino acid
sequence in a
particular protein is
compared between
organisms.
Species that have few
differences are thought to
have shared a common
ancestor more recently. 8
125 45 27
Amino acid differences designed by cbray (with PPT clip art) 67 1
Number of differences from human hemoglobin

11. Amino Acid Difference in Hemoglobin Compared with Human
Biochemical Evidence
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

12. Number of Amino Acid Differences
Amino Acid Difference in Hemoglobin Compared with Human
Biochemical Evidence
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
Where would the common ancestor be?
What organism belongs at each branch? E F
Amino acid differences chart by lpriddy G
Common ancestor

13. Ancient lobe-finned fish
Comparative Anatomy
Homologous structures- structures that share a common ancestry; similar structures with different functions
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish
Homologous structures show:
an organism’s evolutionary past
and common ancestry

14. Comparative Anatomy
Vestigial structures- structures that are present but diminished in size or function
Vestigial structures show:
an organism’s evolutionary past
a common ancestor with species that have similar structures that are still functioning
Examples: Human tailbone, snake pelvic bones and limb bones, and some cave-dwelling salamanders have eyes even though members of the species are completely blind.

15. Comparative Anatomy
Embryology- embryos of different species may appear similar in early stages of development
Example: vertebrate development
Tail buds and pharyngeal pouches
Embryo drawings by cbray

16. Comparative Anatomy Comparison of similarities in embryos can show:
relationships to a common ancestor
Embryo drawings by cbray

17. Geographic Distribution of Organisms
Biogeography
Geographic Distribution of Organisms
Beaver
Muskrat
Beaver and Muskrat
Coypu
Capybara
Coypu and Capybara
Organisms living widely apart (even different continents) may be similar because they share a common ancestor

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