1. Evolution Part 2
Evidence & Types

2. Common Descent with Modification
Darwin proposed that organisms descended from common ancestors
Organisms change over time, diverging from the common form
Caused speciation: evolution of new species

3. Descent With Modification
Takes Place Over Long Periods of Time
Natural Selection Can Be Observed As Changes In
Body Structures
Ecological Niches (role of the organism in its environment)
Habitats

4. Descent With Modification
Implies
All Living Organisms Are Related
Single Tree of Life
DNA, Body Structures, Energy Sources
Common Descent - All Species, Living & Extinct, Were Derived From Common Ancestors

5. Theory of Evolution Today
Supporting Evidence

6. Evidence of Evolution 1. Fossil Record:
Fossil = any preserved remain or imprint of once-living organisms found in layers of sedimentary rock
strongest evidence

7. The fossil record is the ordered arrangement in which fossils appear within sedimentary rocks.
These rocks record the passing of geological time and provides an actual record of the Earth’s past life forms

8. DETERMINING FOSSIL AGE
Relative Dating = estimating a fossil’s age compared with that of other fossils
Gives an approximate age of fossils
Fossils in lower layers are older than fossils in top layers
Radiometric Dating = calculating the age of a sample based on the amount of remaining radioactive isotopes it contains
Half-life = the length of time required for half of the radioactive atoms in a sample to decay

10. Evidence of Evolution 2. Homologous structures
Structures that are similar because of common ancestry (comparative anatomy)
Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure
May Differ In Form or Function
Limb Bones Develop In Similar Patterns
Arms, Wings, Legs, Flippers

12. Evidence of Evolution 3. Analogous structures
Structures that are similar NOT due to a common ancestor but instead a common environment or habitat
Type of comparative anatomy

13. Evidence of Evolution 4. Vestigial Structures
Structures that are no longer used by the organism that have decreased in size and/or function
Examples: whale leg, ostrich wing, human appendix

14. Evidence of Evolution Comparative Embryology
Study of structures that appear during embryonic development.
Organisms that are of a common ancestry will develop in a similar fashion

16. Evidence of Evolution 6. Geographic Distribution of Life forms
Different Animals On Different Continents But Similar Adaptations To Shared Environments

17. Evidence of Evolution 7. Molecular biology (biochemistry):
Study of DNA and proteins (amino acids)
Organisms that are more closely related will have DNA that is more similar

19. Types of Evolution
Microevolution – the change of allele (DNA/gene) frequencies with in a population; small scale
Exp: Peppered Moths
Macroevolution – large scale evolutionary changes
5 Patterns of macroevolution
Mass extinctions
Adaptive Radiation
Convergent Evolution
Coevolution
Punctuated Equilibrium (and gradualism)

20. 5 Patterns of Macroevolution
1. Mass Extinctions
More than 99% of all species that ever lived are now extinct
Mass extinctions wiped out food webs and ecosystems
Exp: Dinosaurs were killed by an asteroid. Could have been many factors (volcanoes & continental drift)

21. 5 Patterns of Macroevolution
2. Adaptive Radiation (Divergent evolution)
A species or group of species evolves into many new species with different adaptations
Exp: Darwin’s finches

22. 5 Patterns of Macroevolution
3. Convergent Evolution
Unrelated species may evolve to resemble one another if they live in very similar environments. Show analogous traits
Example:
1. Ostrich (Africa) and Emu (Australia).
2. Shark, and dolphin (have streamlined bodies that allow them to swim rapidly)

23. 5 Patterns of Macroevolution
4. Coevolution
Evolutionary change, in which one species act as a selective force on a second species, inducing adaptations that in turn act as selective force on the first species.
Example:
Humming birds and plants with
flowers with long tubes

24. 5 Patterns of Macroevolution
5. Punctuated Equilibrium
Patterns of rapid evolution after long periods of equilibrium (balance)
Why? Migration, mass extinctions, isolation

25. 5 Patterns of Macroevolution
How does it appear that GRADUALISM is different?
Gradualism is selection and variation that happens more gradually.