Transcript Evidences of Evolution

In your own words, how
would you define
Evolution?
Can you think of an
example of Evolution?
How do you know when
something has
evolved?
EVOLUTION IS
GENETIC CHANGE
IN A POPULATION
THROUGH TIME.
EVIDENCES OF
EVOLUTION
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:
 Fossil
Record
 Biochemical
 Comparative Anatomy
 Biogeography
 Observable Events
FOSSIL RECORD
 Paleontology
 Fossil
– remains or traces of an
organism that lived long ago
 Remains: ex. bone,
tooth, or shell
 Traces: ex. burrow,
footprint, or
imprint
FOSSIL RECORD
 Most
fossils are found in layered
sedimentary rock


Oldest fossils are
in the lowest
layers
Newest fossils
are in the top
layers
FOSSIL RECORD
 Comparing
fossils from different
layers shows:
 Life on Earth
has changed
 Increased
number of
life forms
BIOCHEMICAL
 DNA
& the genetic code
 One
codon codes for one amino
acid – it works the same way in all
species
 The codon
code for
each amino
acid is the
same in
almost all
organisms.
BIOCHEMICAL
 The
similarity of the way DNA
codes for amino acids shows:
 A probable
common
ancestor for
all life on
Earth
BIOCHEMICAL
 “Universal”
GENETIC CODE
Similar genes
Over the ages, the genetic code
has passed
unchanged (or
nearly so) from
parent to
offspring.
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
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
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
COMPARATIVE ANATOMY
 HOMOLOGOUS
STRUCTURES
 structures
with similar structure
but different function
Turtle
Alligator
Bird
Mammal
COMPARATIVE ANATOMY
 Homologous
structures show
Similar genes – similar proteins
Descent from a common ancestor
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish
COMPARATIVE ANATOMY
 VESTIGIAL
STRUCTURES
organs so reduced in
size that they are
nonfunctioning
remnants of similar
organs in other species
 ex: human tailbone,
appendix, gallbladder,
whale pelvis

COMPARATIVE ANATOMY
 Vestigial
structures show:
an organism’s
evolutionary past
a common ancestor
with species that have
similar structures that
are still functioning
BIOGEOGRAPHY

GEOGRAPHIC DISTRIBUTION
OF ORGANISMS

organisms living far apart may be
similar because they share a
common ancestor
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
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