1

More Than An EyeWitness

Evidence for Evolution

2

Sources of Evidence

From the fossil record

From studies of anatomy

From studies of embryology

From studies of DNA

From observationBiochemistry

3

EVIDENCE FROM FOSSILS

From the fossil record

4

Transitional Organisms

• If evolution has occurred in the past there should be evidence of transitional organisms in the fossil record.

5

Archeopteryx

• Archeopteryx shows evidence of the evolution of birds from reptiles….there is evidence of feathers, a characteristic of birds, and claws, a characteristic of reptiles.

6

EVIDENCE FROM ANATOMY

From studies of anatomy

7

8

Did you write down all your Guesses?

IF SO: CLICK!!!!

9

10

Did you write down all your Guesses?

IF SO: CLICK!!!!

11

Identify how each organism uses its forelimb

Frog Lizard Bat Human Lion Sea Lion

bird

balance Walking flying Multiple

uses

walking swimming flying

12

Anatomical Studies show• Homologous parts – similar in structure but not

necessarily function – evidence of evolution from common ancestor

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

13

Anatomical studies show...

• Name two other organisms that have the ability to fly but have wings very different than those of the bird or the bat?

14

Analogous structures• Butterflies or insects have wings but they are very

different from the birds. These organisms do not have a common ancestor but have adapted to a similar environment. Again evolution explains the similarities.

Copyright © The McGraw Hill Companies. Permission required for reproduction or display

15

Anatomical studies show• Vestigial parts – why does a whale have a pelvis and

femur bones if it has no hind limbs?

16

Vestigial structures

• Why does this salamander have eyes if it never sees the light of day?

17

Vestigial structures

Ear muscles Wisdom teeth Appendix

Human vestigial structures

18

Did you write down all your Answers?

IF SO: CLICK!!!!

19

Why do these structures occur?

• These structures may be homologous to ones that had a function in the ancestors of these organisms thus suggesting their evolution from this common ancestor.

20

Anatomical Studies

• Anatomical studies of cells show a commonality in structure of the cell membrane among almost all living things. Does this suggest a common ancestor for all life?

21

EVIDENCE FROM EMBRYOLOGY

From studies of embryology

22

Embryology Studies• Even though it may not be apparent during the first stage (A)

these five organisms are very different when born and at later stages of embryonic development. Why do they look so similar initially?

Copyright © The McGraw Hill Companies. Permission required for reproduction or display

Stage

(A)

A B C D E

23

Did you THINK about it?

Did you write down all your Guesses?

IF SO: CLICK!!!!

24

Embryology Studies

• The organisms are:– Fish

– Salamander

– Chicken

– Rabbit

– Human

– Why would these five, so different looking organisms at birth, look so similar before birth?

25

More about embryological studies

26

EVIDENCE FROM BIOCHEMISTRY

27

Studies of Biochemistry

Species Sequence of Amino Acids in the Same part of the Hemoglobin Molecule

Human Lys-Glu-His-Iso

Horse Arg-Lys-His-Lys

Gorilla Lys-Glu-His-Lys

Chimpanzee Lys-Glu-His-Iso

Zebra Arg-Lys-His-Arg

28

Which organisms appear to be more closely related to each

other?Human and chimpanzee have no

differences in their amino acid sequence suggesting their close evolutionary

relationship, they have a more recent common ancestor. Studies of other

chemicals, like proteins used in digestion, show similar comparisons in these

organisms.

29

EVIDENCE FROM DNA

From studies of DNA

30

DNA

• The sequence of the nucleotides making up their DNA would also be similar because DNA determines the sequence of amino acids in proteins.

From studies of DNA

31

DIRECT OBSERVATION OF EVOLUTION OCCURRING IN MODERN DAY ORGANISMS

From observation

32

Observations of Evolution in modern organisms

• Mosquitoes resistance to insecticides

• Bacteria resistance to antibiotics

• New strains of Plasmodium that cause Malaria

• New strains of TB (tuberculosis)

• Peppered moth

• Darwin finches

33

Has and Does Evolution Occur?

• Scientists do not dispute that evolution does occur. Evolution is a FACT.

• How evolution occurs is not completely understood.• Charles Darwin explained how evolution occurred

through natural selection. Natural selection is a well documented THEORY uniting all of biology.

• Modern evolutionary theory uses ideas of genetics, particularly mutations, to help explain how evolution may occur. (Darwin didn’t know about mutations.)