1. How populations change over time
Population Genetics
How populations change over time

2. Hardy-Weinberg
States that without outside factors acting on a population, allele frequencies would remain the same = NO EVOLUTION
Factors affecting evolution:
Genetic drift
Gene flow
Nonrandom mating
Mutations
Natural selection

3. Genetic Drift ANY change in allele frequencies Founder Effect:
occurs when a small sample of the population is separated from the rest
Bottleneck Effect:
Population declines to a very low number and then rebounds
BOTH RESULT IN
Organisms breed with one another
Might see new/uncommon traits emerge

4. Gene Flow
Individuals are always moving into and out of habitats based on competition and/ or predation
Immigration and emigration
Causes NEW allele frequencies

5. Gene Flow
Introduced species Purple loosestrife, originally brought to North America accidentally on cargo ships, reproduces very quickly and aggressively, often crowding out species like the cattail.

6. Nonrandom Mating
Organisms mate with individuals in close proximity  promotes inbreeding
Could lead to a change in allele frequencies (mutations)

7. Nonrandom Mating
ALSO includes sexual selection  mate chosen based on “best” genes
Mating call/dance
Gifts
Fighting

8. Mutation Random change in genetic material May be harmful or lethal
Might ALSO be beneficial

9. Natural Selection
Acts to select the individuals that are best adapted to their environment
Changes allele frequencies and phenotype
Stabilizing: neither extreme is good  human baby weight
Directional: influenced by environment Peppered Moth’s response to pollution
Disruptive: both extremes work for different habitats  retains individuals expressing extreme traits

10. Speciation Species diverge when they are isolated
Allopatric ( physical barrier)
Sympatric (no physical barrier)

11. Rate of Speciation
Punctuated Equilibrium
Gradualism