Transcript Evidences of Evolution

TEACHER NOTES
 This
PowerPoint was revised
January 3, 2005.
EVIDENCES OF
EVOLUTION
Fossil Record
Biochemical
Comparative Anatomy
Biogeography
Observable Events
EVOLUTION IS
Genetic change in a
population through time.
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.
Evidences of Evolution
Today most evidences for
evolution are grouped into five
main categories:
 Biochemical
 Fossil
Record
 Comparative Anatomy
 Biogeography
 Observable Events
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
1 - FOSSIL RECORD
 Most
fossils are found in layered
sedimentary rock
 Oldest
fossils are on
the lowest
layer
1 - FOSSIL RECORD
 Comparing
fossils from different
layers shows:
 Life on Earth
has changed
 Increased
number of
life forms
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.
2 - BIOCHEMICAL
 The
similarity of triplet DNA
codes making-up amino acids
shows:
 A probable
common
ancestor for
all life on
Earth
2 - BIOCHEMICAL
 “Universal”
GENETIC CODE
Similar genes
Over the ages, the genetic code
has passed
unchanged (or
nearly so) from
parent to
offspring.
2 - BIOCHEMICAL
 AMINO
ACID SEQUENCING
 The
amino acid
sequence in a
particular
protein is
compared
between
organisms.
45
27
67
1
Number of differences
from human hemoglobin
2 - BIOCHEMICAL
 Comparing
amino acid sequence
shows:
Amino
Acid of

Closeness
Sequencing
is
relationship
probably the
 A probable
STRONGEST
common
evidence
for
ancestor
relationships
among
Human hemoglobin
organisms.
has 146 amino acids
Amino Acid Difference in
Hemoglobin Compared
with Human
Species
Difference
Gorilla
1
Rhesus Monkey
8
Mouse
Chicken
Frog
Lamprey
27
45
67
125
2 - BIOCHEMICAL

CLADOGRAM: diagram that
shows the evolutionary
relationship among a
group of organisms.
B
A
Where
would the
What organism
common
belongs
at each
ancestor
be?
branch?
Common
ancestor
150
C
D
Species Difference
Gorilla
1
Monkey
8
Mouse
27
Chicken
45
Frog
67
Lamprey
125
E
F
G
10 0
20
30
50 40
100
Number of Amino Acid Differences
3 COMPARATIVE ANATOMY
 HOMOLOGOUS
STRUCTURES
 structures
with similar structure
but different function
 ex: limbs of vertebrates (turtle,
alligator, bird, mammal)
Turtle
Alligator
Bird
Mammal
3 COMPARATIVE ANATOMY
 Homologous
structures show
Similar genes
Descent from a common ancestor
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish
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

3 COMPARATIVE ANATOMY
 Vestigial
structures show:
an organism’s
evolutionary past
a common ancestor
with species that have
similar structures that
are still functioning
3 COMPARATIVE ANATOMY
 EMBRYOLOGY
 Embryos
of different species
may appear similar in early
stages of development
 ex:
vertebrate
development
3 COMPARATIVE ANATOMY
 Comparison
of
similarities in
embryos can
show:
Relationship
to a common
ancestor
4 - BIOGEOGRAPHY

GEOGRAPHIC DISTRIBUTION
OF ORGANISMS
 organisms living
widely apart
(even different
continents) may
be similar
because they
share a common
ancestor
Shows common
ancestor
Beaver
Muskrat
Beaver and
Muskrat
Coypu
Capybara
Coypu and
Capybara
5 - 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
5 - 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
Works Cited

“Geographic Distribution of Organisms” photo:
Miller, Kenneth and Levine, Joseph. (2004).
Biology. Prentice Hall.