1. Answer in writing: what is DNA? Where is yours?
A very long macromolecules that contains your genetic material. It’s found in the nucleus of each one of your cells.
Answer in writing: what is a gene?
A segment of DNA which codes for a protein, which determines a trait.

2. 4 Mechanisms of Evolution
Evolution: a change in gene frequencies in a population between generations
4 Mechanisms of Evolution
Gene flow (migration)
Genetic drift (population bottlenecks)
Mutation
Natural selection

3. Mechanisms of Evolution 1: Gene Flow (Migration)
The exchange of genes between populations
decreases variation in population emigrated from
increases variation in population immigrated to
a significant force in human evolutionary history (no speciation)
accelerated travel/gene flow in recent years
What was an example of gene flow in “the island of the colorblind?” Look at your video sheet and write “gene flow” next to it.

4. Polydactyly (Ellis-van Creveld syndrome)
Mechanisms of Evolution 2: Genetic Drift
occurs with isolation (absence of gene flow) and/or small population size
founder effect (e.g. first settlers on an island)
genetic bottlenecks (e.g. depopulation from catastrophe)
Polydactyly (Ellis-van Creveld syndrome)
What was an example of genetic drift in “the island of the colorblind?” Look at your video sheet and write “gene flow” next to it.

5. “The Island of the Colorblind” as an example of (three) forces of evolution:
a bounded population
a mutation: achromatopsia gene
arrival of a European achromatopsia gene in the 18th century: gene flow (migration)
isolation: genetic drift
the typhoon: genetic drift (population bottleneck)
religious practices (encouraged inbreeding): genetic drift

6. Forces of Evolution 3: Mutation
Mutation is the source of new genetic variation:
actual change in a portion of the DNA of an organism.
some harmful, some beneficial, most have no effect and are passed unnoticed to offspring.
most common type of mutation is caused by copying errors during meiosis (sex cell division)
mutations do not cause evolution, they provide the material upon which the other evolutionary mechanisms act. Only way to introduce genetic variation from within a population.
Example: sickle cell anemia: mutation of recessive hemoglobin gene. Misshapen red blood cells cannot transport oxygen to tissues.

7. Sickle-cell hemoglobin HbS HbS
1. Hemoglobin molecule
Normal hemoglobin
HbA HbA
valine
2. Hemoglobin beta chain
3. Red blood cells

8. Forces of Evolution 4: Natural Selection
mutation on its own has little effect on changing allele frequencies
but mutation + natural selection = rapid evolutionary change
sickle-cell carriers are protected from malaria
Distribution of malaria
Distribution of sickle-cell anemia

9. Forces of Evolution 4: Natural Selection
sickle-cell carriers are protected from malaria
What is evolution? - a change in genes frequency in a population between generations
- sickle-cell genes decline in frequency when malaria is not present
- ex: decrease sickle-cell genes in African American population

10. Forces of Evolution 4: Natural Selection
Natural selection: some individuals have genes that allow them to survive and reproduce more than other individuals.
These individuals have higher fitness (more offspring), and by producing more offspring, will pass on more genes to the next generation.
This increases the frequency of their genes in the population = natural selection!
Natural selection acts on the individual, although the population evolves.