1. Ch. 19 Warm-Up
Compare and contrast natural selection vs. artificial selection.
What are the key ideas of natural selection?
Define and give an example for the following:
Homologous structure
Vestigial structure
Analogous structure

2. Descent with Modification Part B: Evidence for Evolution
Chapter 19
Descent with Modification
Part B: Evidence for Evolution

3. Recap main ideas of natural selection:
Evolution is change in species over time.
There is overproduction of offspring, which leads to competition for resources.
Heritable variations exist within a population.
These variations can result in differential reproductive success.
Over generations, this can result in changes in the genetic composition of the population.
Remember:
Individuals do NOT evolve! Populations evolve.

4. Evidence for Evolution:
Direct Observations
Homology
Fossil Record
Biogeography

5. Evidence for Evolution
1. Direct Observations
2. Homology
3. Fossil Record
4. Biogeography

6. Evidence for Evolution: 1. Direct Observations
Examples:
Insect populations become resistant to pesticides (DDT)
Antibiotic-resistant bacteria (MRSA)
Peppered moth (pollution in city vs. country)

7. The Rise of MRSA (methicillin-resistant Staphylococcus aureus)

8. Evidence for Evolution: 2. Homology
Homology: characteristics in related species can have underlying similarity even though functions may differ
Examples:
Homologous structures: similar anatomy from common ancestors (eg. forelimbs of human/cat/whale/bat)
Embryonic homologies: similar early development (eg. vertebrate embryos with tail & pharyngeal pouches)
Vestigial organs: structures w/little or no use (eg. flightless bird wings)
Molecular homologies: similar DNA and amino acid sequences

9. Homologous Structures

10. Embryonic Development

11. Vestigial Structures

12. Molecular Homologies
Compare DNA and amino acid sequences

13. Convergent Evolution
Distantly related species can resemble one another
Similar problem, similar solutions!
Analogous structures: similar structures, function in similar environments
Eg. Torpedo shape of shark, penguin, & dolphin

14. Evidence for Evolution: 3. Fossil Record
Fossils = remains or traces of organisms from past
Found in sedimentary rock
Paleontology: study of fossils
Show evolutionary changes that occur over time and origin of major new groups of organisms
Ankle bones

15. Prokaryotes (oldest fossils)  eukaryotes (fish – amphibians – reptiles – birds – mammals)
Transitional forms = links to modern species

16. Evolutionary Tree

17. Evidence for Evolution: 4. Biogeography
Biogeography = geographic distribution of a species
Species in nearby geographic areas resemble each other
Continental drift and Pangaea explains similarities on different continents and where oldest fossils are found
Eg. Oldest horse fossils are found in North America (before it was connected to South America)

18. Island Biogeography

19. Galapagos Tortoises

20. Endemic species: found at a certain geographic location and nowhere else
Eg. Marine iguanas in the Galapagos

21. Tree of Life

22. HHMI Short Film: Natural Selection & Adaptation
Rock Pocket Mice
Running Time: 10:25 min