1. Evolution Evidence
Chapter 22
Part 2 – Revised AP Bio.

2. Questions (Page 1 of 2) 1. What is evolution?
2. What is the dominant (most common mode) of evolution?
3. Can evolution arise without natural selection?
4. Name 2 purposeful mechanisms of evolution that do not include natural selection.

3. Questions (Page 2 of 2) 5. Name 2 “random” mechanisms of evolution.
6. How do individuals evolve resistance to bacteria or viruses?
7. Name 2 sources of evidence for evolution.
8. What are the 2 principles that underlie natural selection?
9. How does microevolution differ from macroevolution?

4. Evidence for Evolution
Direct observation of Evolutionary change
Antibiotic-resistant bacteria & drug-resistant virus populations
The Fossil Record
Paleontology – study of fossils
Fossils show that evolutionary changes have occurred over time
Punctuated equilibrium instead of gradualism
Long periods of stasis punctuated by brief bursts of evolutionary activity

5. Evidence for Evolution (Page 2)
Homology and Convergent Evolution
Homology – structural similarity resulting from common ancestry
Homologous structures – anatomical signs of evolution
Embryonic homologies
Early stages of animal development reveal many anatomical homologies that are not present in the adult form
In vertebrates, Ontogeny recapitulates Phylogeny

6. Anatomical Homologies

7. Ontogeny recapitulates Phylogeny

8. Evidence for Evolution (Page 3)
Vestigial organs
Structures of dubious utility
Remnants of previously important structures
Appendix (humans)
Limb remnants (snakes)

9. Evidence for Evolution (Page 4)
Molecular homologies
Homologies at the molecular level
Everything uses DNA & RNA
Humans & Chimps – 99% same DNA (bonobos = 98.7%)
Amino acid sequences in hemoglobin in primates is extremely similar (common ancestor)
Convergent Evolution
Two organisms develop similarities as they adapted to similar environments
Analogous structures result, not homologous

10. Stingrays – were dorsoventrally flattened, so they lie on their belly
 Note the midline location of the “backbone” column
Flounders – laterally flattened, so they lie on their sides
 Note the vertebral column on the right

11. Homology v. Analogy Homologous structures show evidence of relatedness
Whale fin/Bat wing
Analogous structures show similar solutions to similar problems, but do NOT indicate relatedness
Ray and flounder ventral orientation

12. Biogeography The geographical distribution of a species
Closely related species tend to be found in the same geographical region
Continental drift – breakup of pangaea
Can explain species similarity in disparate geographic regions
Endemic species
Species found in one geographic location and nowhere else
Example: marine iguanas in Galapagos

14. Artificial Selection
Human controlled selecting and breeding of organisms to produce desirable traits (for humans)
Selective breeding of domesticated plants and animals influenced Darwin’s thinking
Crop plants and animals often bear little resemblance to their wild ancestors
Artificial selection can change much in a short period of time. Natural selection may be able to do so as well