Evolution:

1
Evolution

• Supporting Evidence

2
The following items demonstrate descent with
modification, as well as common ancestry.
(Darwins principle of common descent)
3
I -Fossil Evidence (descent with modifications)

• Horse fossils indicate changes in size,
• as well as the transition from toes to hooves.

4
I - Fossil Evidence Continued

• These mollusk
• fossils show
• the development
• of torsion, the
• twisting of
• their shells.

5
II -Homologous Structuresare fundamentally
similar in their makeup, position and
development, but are adapted to different
functions.

• Animal Forelimbs

6
(No Transcript)
7

• The Galapagos finch beaks are said to
• be homologous. They originated in a
• common ancestor and have adapted to
• various environments.

8
Homologous v. Analogous

• Whats the Difference?
• Homologous structures are features that
  originated in a shared ancestor. They have
  different mature forms, but develop from the same
  embryonic tissue.
• They are inherited from a common ancestor.

9

• Analogous Structures have features that have
  identical functions, and look somewhat alike, but
  they may be different in internal anatomy.
• The evolved independently after their point
  of common ancestry, so they were not inherited
  from a common ancestor.

A birds wing and a moths wing are
analogous. They allow the animals to fly,
but They have greatly different development and
internal structure.
10
Moth Wing Structure
11
(No Transcript)
12
Catoblepia berecynthia
13
Bird Wing Anatomy
Bones Feathers
14
Also Analogous Insect horse legs
15
III -Vestigial Structureswhich may have been
functional in an ancestor, are functionless and
underdeveloped in later generations

• Human tailbone
• (coccyx)
• Human Appendix

16
III - Vestigial Structures Structures that are
vestigial in one organism, may be functional in
others.

• Nictitating membrane
• Ear muscles

17
III - Vestigial Structures (continued)

• Limb bones
• in snakes
• Pelvic
• bones
• in whales

18
III Vestigial StructuresContinued

• Erector pili muscles
• which cause goose bumps
• in humans
• Human baby
• born with fleshy
• tail

19

• Does the tail
• really exist?

20

• Baby girl
• born in a hospital
• in Chile

21
IV -Embryological Similarities

• Various embryos in early stages show
• evidence of gills slits and tails.

22
V - Biochemical Evidence

• All organisms have DNA
• ( RNA)
• All organisms have ATP
• Similarities in cell respiration
• enzymes

23
V- Biochemical Evidence(Continued)

• All organisms have cytochrome c
• in the electron transport chain
• (The difference in A.A.s is proportional to the
  length of time that has passed since the two
  shared a common ancestor.)

24
VI Homeotic Genes

• Homeotic genes (Hox genes) regulatory genes that
  determine where certain anatomical structures,
  such as appendages will develop in an embryo.
  They seem to be master genes of development that
  determine the overall body organization.
• Common ancestry is demonstrated because
  animals share many of these Hox genes, which may
  control the development of similar regions.

25
(No Transcript)
26
In Summary

• Scientists have continued to observe examples
  of common ancestry and descent with modifications
  
• since Darwin observed finches on the
  Galapagos Islands so many years ago.