1. Population Genetics and Evolution
Gene Pools
Hardy-Weinberg
5 Fingers of Evolution

2. The bell curve
Traits vary and can be mapped along a bell curve, which shows that most individuals
have average traits, whereas a few individuals have extreme traits.

4. What causes phenotype variations?
*Genetic variations cause variations in phenotypes
How do variations come about within the same species?
1) Mutations in gametes form new alleles
2) Sexual reproduction
-Crossing over in meiosis
-Independent assortment
-Fertilization

5. The Gene Pool
Gene Pool – all of the alleles for every gene of a particular population

6. Allele Frequencies
Allele frequency- how often an allele occurs in a populations gene. w W w w w w W w w w w w w w w w w w W w w w W w
Calculate the Allele frequencies for W and w!

7. Genotype Frequencies
Genotype Frequencies- the percent of the population that is homozygous dominant, heterozygous and homozygous recessive at any given time. Example: Population total: 2396 AA = 910 Aa=695 aa= 791 Calculate genotype frequencies…

8. Genotype Frequencies
Dimples are dominant to no dimples. 20% of the population has no dimples. How many people of a population of 5437 are homozygous recessive?

9. Hardy-Weinberg Equilibrium
It is a theoretical model of a population in which no
evolution occurs and the gene pool of the population is stable. Allele frequencies and genotype frequencies do not change.
5 Conditions for Equilibrium
1) Large Population (no genetic drift)
2) Random mating
3) No mutations
4) No gene flow – no immigration or emigration
5) No natural selection
If at least one of these conditions is NOT met, then the population is EVOLVING!

10. 5 Causes of Evolution 1) Genetic drift occurs in small populations
2) Sexual selection occurs when certain traits increase an individual’s success at mating
3) Mutations- a change in DNA changes allele frequencies
4) Gene flow- genes move in and out of the population due to immigration and emigration
5) Natural Selection (3 types)…

11. Gene Flow
Movement of fertile individuals between populations (immigration and emigration
-Gain/lose alleles from one population
-Reduce genetic differences between populations

12. Genetic Drift Genetic Drift 2 Types:
Bottle neck-A random event such as a fire or flood that causes change.
It kills individuals regardless of traits —any one can die or be lucky enough to survive
Founder Effect- Individuals leave a large population to establish a new population. Only alleles that came with the founders will be passed on.

16. Polydactyly in Amish population
Founder Effect
A few individuals isolated from larger population
Certain alleles under/over represented
Polydactyly in Amish population

17. 3 Types of Selection

18. The bell curve
Traits vary and can be mapped along a bell curve, which shows that most individuals
have average traits, whereas a few individuals have extreme traits.

19. Directional Selection
Favors the formation of more-extreme traits.

20. Stabilizing Selection
Favors the formation of average traits.

21. Disruptive Selection
Favors extreme traits rather than average traits

22. Natural Selection
Genetic Drift

23. Genetic Drift vs. Natural selection
-A random event such as a fire or flood that causes change.
It kills individuals regardless of traits —any one can die or be lucky enough to survive
Natural selection
-An prolonged or permanent change in the environment which causes individuals with certain traits to succeed and others to die

24. Big Ideas *Natural selection acts directly on phenotypes
*Gene pools and allele frequencies
change as a result of evolution