1. Hardy-Weinberg Principle
Evolution
Hardy-Weinberg Principle

2. Intro Last day we left off talking about populations…
Populations geneticists are able to quantify the total number of alleles within a population ==this is known as the gene pool
They are able to accomplish this by measuring each allele frequency, which is the proportion of gene copies in a population for a given allele
Therefore evolutionary changes in populations can be quantitatively measured by looking for changes in allele frequencies

3. Example

4. Hmmm…
In terms of evolution, would the dominant form of a moth wing become more and more common over time?
Do allele frequencies remain constant or change over time?
These questions were answered independently (think Darwin vs. Wallace) by a mathematician named Hardy and physicist named Weinberg== thus Hardy-Weinberg principle

5. The Principle
Allele frequencies will not change over time (generation-generation) if the following conditions are met:
The population is very large
Mating opportunities are equal
No mutations occur
No migration occurs
All individuals have an equal chance at reproductive success==no natural selection

6. Equation
The H-W-P is often expressed using the following equation (for a gene with only 2 alleles==A/a):
let p=frequency of A and q=frequency of a, then
p+q=1
(p+q)2= 1
p2 + 2pq + q2 = 1, where
p2 = frequency of AA; 2pq= frequency of Aa; and q2 = frequency of aa

7. Moth example
Note: genotype frequencies will remain the same from generation to generation as long mating is random

8. Reference
Pgs Pg 549 PP’s #1-3 Quiz Tomorrow -self quiz -review #1-4, 7, 8, 10, 15