Evidence of Evolution

1
Evidence of Evolution

• This PowerPoint was revised Jan 1, 2010 for Unique

2
EVOLUTION IS

• GENETIC CHANGE IN A POPULATION THROUGH TIME.

3

• EVIDENCES OF EVOLUTION

4
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.

5
Evidences of Evolution

• Today most evidences for evolution are grouped
  into five main categories

• Biochemical
• Fossil Record
• Comparative Anatomy
• Biogeography
• Observable Events

6
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

7
FOSSIL RECORD

• Most fossils are found in layered sedimentary rock

• Oldest fossils are on the lowest layer

8
FOSSIL RECORD

• Comparing fossils from different layers shows

• Life on Earth has changed
• Increased number of life forms

9
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.

10
BIOCHEMICAL

• The similarity of triplet DNA codes making-up
  amino acids shows

• A probable common ancestor for all life on Earth

11
BIOCHEMICAL

• Universal GENETIC CODE
• Similar genes
• Over the ages, the genetic code

• has passed unchanged (or nearly so) from parent
  to offspring.

12
BIOCHEMICAL

• AMINO ACID SEQUENCING

• The amino acid sequence in a particular protein
  is compared between organisms.

Number of differences from human hemoglobin
13
BIOCHEMICAL

• Comparing amino acid sequence shows

Amino Acid Difference in Hemoglobin Compared with
Human

• Closeness of relationship
• A probable common ancestor

Amino Acid Sequencing is probably the STRONGEST
evidence for relationships among organisms.
Species Difference
Gorilla 1
Rhesus Monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey 125
Human hemoglobin has 146 amino acids
14
BIOCHEMICAL
Amino Acid Difference in Hemoglobin Compared with
Human
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
What organism belongs at each branch?
Where would the common ancestor be?
E
F
G
Common ancestor
15
COMPARATIVE ANATOMY

• HOMOLOGOUS STRUCTURES

• structures with similar structure but different
  function
• (ex turtle, alligator, bird, mammal)

16
COMPARATIVE ANATOMY

• Homologous structures show

• Similar genes
• Descent from a common ancestor

17
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

18
COMPARATIVE ANATOMY

• Vestigial structures show

• an organisms evolutionary past
• a common ancestor with species that have similar
  structures that are still functioning

19
Analogous Structures
COMPARATIVE ANATOMY

• Unrelated species have evolved to have similar
  adaptations

20
COMPARATIVE ANATOMY

• EMBRYOLOGY
• Embryos of different species may appear similar
  in early stages of development

• ex vertebrate development

21
COMPARATIVE ANATOMY

• Comparison of similarities in embryos can show

• Relationship to a common ancestor

22
BIOGEOGRAPHY

• GEOGRAPHIC DISTRIBUTION OF ORGANISMS

• organisms living widely apart (even different
  continents) may be similar because they share a
  common ancestor

• Shows common ancestor

23
OBSERVABLE EVENTS

• Some changes in species have been observed and
  studied

Peter Rosemary Grants Study of Beak Size Shift in Darwins Finches H. Kettlewells Study of Peppered Moth Color Shifts

24
OBSERVABLE EVENTS

• Observable events show that evolution is an
  ongoing process

Peter Rosemary Grants Study of Beak Size Shift in Darwins Finches H. Kettlewells Study of Peppered Moth Color Shifts

25
Works Cited

• Miller, Kenneth and Levine, Joseph. (2004).
  Biology. Prentice Hall.