Transcript Evidences of Evolution

EVIDENCES OF
EVOLUTION
Fossil Record
Biochemical
Comparative Anatomy
Biogeography
Observable Events
Artificial Selection
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
 Artificial selection
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
in the deeper
layers
 Life on Earth has
changed
 Increased
number of life
forms

Fossil Record
The fossil record is the history of life recorded by
remains from the past. Most fossils are at least
10,000 years old.
1. Body Fossils
2. Trace Fossils
2 - BIOCHEMICAL
 THE
GENETIC CODE
 Triplets
of DNA nitrogen-base
sequences that code for specific
amino acids
 The
sequences of
bases that
code for
amino acids
are 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 different mature forms
but develop from the same embryonic
tissue
 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
Homology
• Homology: a similarity between
species that is the result from the
inheritance of traits from a common
ancestor
•The features of every creature reflect
history as well as adaptation
• 3 types of homologies
- structural
- developmental
Homology vs. Analogy
Natural selection appears to have favored similar
adaptations in unrelated organisms in similar
environments--> these structures are analogous
Whereas homologous
structures
share structural similarity,
but not function, analogous
structures share function
but not structural similarity
since they evolved
independently
Genetic Homologies
All living organisms share
the same genetic code
Chromosome and gene similarities betw
species match evolutionary similarities
This is true for both coding regions and
“junk DNA”
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
 an organism’s evolutionary past
 a common ancestor with species
that have similar structures that
are still functioning

Vestigial Structures in
Humans
Tailbone
Wisdom Teeth
Appendix
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
 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
6. Artificial Selection

Process by which plants and animals
used by humans in agriculture,
horticulture, and companionship have
been derived from wild organisms

Humans use the best or more useful
traits provided by nature and pass on to
future generations
6. Artificial Selection
http://www.gly.uga.edu/railsback/1122/1122Dogs.jpeg
6. Artificial Selection
Picture depicting
how farmers have
cultivated wild
mustard and
selected the
desirable traits
Nature provides
the variations and
humans select
those variations
that they find most
useful
Works Cited

“Geographic Distribution of Organisms” photo:
Miller, Kenneth and Levine, Joseph. (2004).
Biology. Prentice Hall.

McGraw-Hill
http://pages.uindy.edu/~sdavis/b280/
lectures/3evidence1280.ppt.