3. Charles Darwin
On his journey around the world,
Darwin found evidence of
gradual change (evolution).
Darwin cited
evidences he
found in fossil
records,
geographic
distribution and
homologous
structures.
4. Evidences of
Evolution
Today most evidences for
evolution are grouped into
four main categories:
Biochemical
Fossil Record
Comparative Anatomy
Observable Events
5. 1 - FOSSIL RECORD
Paleontology – study of fossils
Fossil – remains or traces of an
organism that lived long ago
Remains: ex. bone,
tooth, or shell
Traces: ex. burrow,
footprint, or
imprint
6. 1 - FOSSIL RECORD
Most fossils are found in layered
sedimentary rock
Oldest fossils
are on the
lowest layer
7. 1 - FOSSIL RECORD
Comparing fossils from different
layers shows:
🞾 Life on Earth
has changed
🞾 Increased
number of
life forms
8. 2 - BIOCHEMICAL
THE GENETIC CODE
Triplets of DNA nitrogen-base
sequences that code for specific
amino acids
The amino
acid triplet
is the
same in
almost all
organisms.
9. 2 - BIOCHEMICAL
The similarity of triplet DNA
codes making-up amino acids
shows:
🞾 A probable
common
ancestor for
all life on
Earth
10. 2 - BIOCHEMICAL
“Universal” GENETIC CODE
🞾 Similar genes
🞾 Over the ages, the genetic code
has passed
unchanged (or
nearly so) from
parent to
offspring.
11. 2 - BIOCHEMICAL
AMINO ACID SEQUENCING
The amino acid
sequence in a
particular
protein is
compared
between
organisms. Number of differences from
human hemoglobin
45
1
67
27
12. 2 - BIOCHEMICAL
Comparing amino acid sequence
shows:
Species Difference
Gorilla 1
Rhesus Monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey 125
Amino Acid Difference in
Hemoglobin Compared
with Human
Closeness of
relationship
A probable
common
ancestor
Human hemoglobin
has 146 amino acids
Amino Acid
Sequencing is
probably the
STRONGEST
evidence for
relationships
among
organisms.
13. 2 - BIOCHEMICAL
CLADOGRAM: diagram that
shows the evolutionary
relationship among a
group of organisms.
Species Difference
Gorilla 1
Monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey 125
Amino Acid Difference
in Hemoglobin
Compared with Human
Number of Amino Acid Differences
150
100
50
0
40
20
30
10
G
F
E
D
C
B
A
Common
ancestor
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14. 3 COMPARATIVE ANATOMY
HOMOLOGOUS STRUCTURES
structures with similar structure
but different function
ex: limbs of vertebrates (turtle,
alligator, bird, mammal)
Turtle
Alligator
Bird
Mammal
15. 3 COMPARATIVE ANATOMY
Homologous structures show
🞾 Similar genes
🞾 Descent from a common ancestor
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish
16. 3 COMPARATIVE ANATOMY
VESTIGIAL STRUCTURES
organs so reduced in
size that they are
nonfunctioning
remnants of similar
organs in other species
ex: human tailbone,
appendix, whale pelvis
17. 3 COMPARATIVE ANATOMY
Vestigial structures show:
🞾 an organism’s
evolutionary past
🞾 a common ancestor
with species that have
similar structures that
are still functioning
18. 3 COMPARATIVE ANATOMY
EMBRYOLOGY
Embryos of different species
may appear similar in early
stages of development
ex: vertebrate
development
19. 3 COMPARATIVE ANATOMY
Comparison of
similarities in
embryos can
show:
🞾 Relationship
to a common
ancestor
20. 4 - OBSERVABLE EVENTS
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
21. 4 - OBSERVABLE EVENTS
🞾 Observable events show that
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
22. Works Cited
“Geographic Distribution of Organisms” photo:
Miller, Kenneth and Levine, Joseph. (2004).
Biology. Prentice Hall.
