1. Hardy Weinberg
What the heck is that?

2. Let’s look at Evolution
What is a gene pool?
includes all the alleles for all the genes present in the population
So what does this mean?
Means we can calculate different types of frequencies
Allele frequencies
Genotype frequencies

3. Suppose for example, that there are 1000 people in a population and they have the following genotypes for a trait:
Genotype Number AA 490 people Aa 420 people aa 90 people Total: 1000 people

4. What is the genotype frequency?
Genotype Number AA 490 ppl Aa 420 aa 90 Total: 1000
490/1000 = 0.49
420/1000 = 0.42
90/1000 = 0.09
Add all the genotype frequencies up and they should equal 1.0.

5. What is the phenotype frequency?
Genotype Number AA 490 ppl Aa 420 aa 90
910/1000 = 0.91
90/1000 = 0.09
Equals 1.0
There are 2 phenotypes
Dominant
Recessive
How many dominant individuals are there?
= 910
How many recessive individuals are there? 90

6. What is the allele frequency?
Genotype Number
AA ppl Aa aa
1400/2000 = 0.7
600/2000 = 0.3
Total is 1.0
There are 2 alleles A a
So how many individuals have A?
= 1400
How many individuals have a?
= 600

7. Yes, if evolution was occurring
Do you think these frequences (genotype, phenotype and allelic) would change over time?
Yes, if evolution was occurring

8. These frequencies _________ change if the population was in genetic equilibrium.
WOULD NOT

9. So these 2 guys, Hardy and Weinberg got together and said that if certain conditions are kept constant, large populations will not change their frequencies.
So what are these conditions?

10. Five conditions are: Random mating – no selection of mates
No net mutations
Large population size
No migration (immigration or emigration)
No natural selection – no favoring of phenotypes

11. The best thing about Hardy Weinberg is
It can be represented mathematically! And I know how much you guys LOVE math 

12. Symbols to memorize P = frequency of dominant allele (A)
Q = frequency of recessive allele (a)
And P+Q = 1; why?
Because all students in the population are either dominant or recessive

13. Equations to memorize P2 = frequency of homozygous dominant (AA)
2pq = frequency of heterozygous dominant (Aa)
Q2 = frequency of the recessive (aa)
Also, P2 + 2pq + Q2 = 1; why?
Because all people fall in one of those 3 groups above

14. So from our example earlier,
What is Q2?
What is Q?
What is P?
Does P + Q =1 in this example?
What is P2?
What is 2pq?
Does , P2 + 2pq + Q2 = 1 in this example?
0.09
Genotype Number
AA 490 ppl
Aa 420
aa 90
0.3
0.7; remember p+q=1
= 1; yes
P = 0.7, so (0.7)2 = 0.49
2(0.7)(0.3) = 0.42
= 1; yes