1. The Evolution of Populations and Speciation
Chapter 16
The Evolution of Populations
and Speciation

2. Stabilizing, Directional, and Disruptive Selection

3. Map of Homo sapiens Migration

4. Comparing Hypotheses on Rates of Evolution

6. Spatial barriers

7. Example of Speciation

9. Archipelagos: founder effects and adaptive radiation
“Darwin’s Finches”
obs: finches w/similar body morphology to common S.Am. sp. have widely varying beak morphologies and behaviors

11. Analogy Adaptive Convergence
Similarities due to similar environments not common ancestors

12. Convergences
Whale - mammal
Shark - fish

13. Under what conditions would change not occur?
Mechanisms of Change
Under what conditions would change not occur?

14. Mechanisms of Change Gene Frequency Illness Vector Gene Pool
Artificial Selection
Gene Shuffling
Inheritable Variation
Genetic Drift

15. Hardy-Weinberg Theory Assumptions
Evolution will not occur if there is:
A large population (gene pool), or large enough that there are no sampling errors
Random mating
No selective advantage for genotypes - no selective breeding
No mutations
No migration in or out of the population
No genetic drift

16. Hardy-Weinberg Formula
p2 + 2pq + q2 = 1
p = dominant allele frequency
q = recessive allele frequency
1 = gene pool of that trait

17. Variations or Diversity Result from
Genetic drift - change in gene pool due to chance.
Founder effect - new gene pool established by founding population
Bottleneck effect - natural disaster wipes out most of the population. Survivors establish a new gene pool.
Be sure to refer to the text, because it gives good examples of all of these methods of establishing diversity.

18. Genetic bottlenecks: cheetahs
only remnant populations remain
high degree of genetic similarity among individuals.
shared “bad”alleles: low sperm quantity and quality
lowered disease resistance

19. Don’t forget it isn’t just change in animals!
Ecological Succession!
Change in habitat from bare rock to forest
Bare rock (like after a landslide or volcano eruption)
Lichens and mosses are first inhabitants
Grasses move in as rocks start to break down and soil starts to build
Low shrubs and brushes follow
Then bigger brushes and willows and some trees
Trees and then mature forest take over until next the disaster