1. Genetic variation and Change in populations
Population Genetics
Genetic variation and Change in populations
Population: All Organisms in a geographic area that are the same species and capable of interbreeding.
Genetic Variation:
allele frequency changes over time
Exchange of genetic Material

2. Allele Frequency how often that allele form appears in a population (as a decimal)
Reminder!
Allele is a form of a gene
Each individual has 2 alleles for each gene so…
.5 = 50%, .62=62%, etc…
# of individuals = # of total alleles 2
OR…
# of alleles = # of individuals x 2

3. p + q = 1 P = frequency of the dominant allele
Q = Frequency of the recessive allele
In kermitfrogs the frequency of the dominant allele for being green is .84 (84%). What is the frequency of the recessive allele?

4. Hardy-Weinberg Equation: P2 + 2pq + q2 = 1
This equation tells you the frequency of genotypes in the population
P2 = Homozygous dominant genotype
2pq = heterozygous genotype
Q2 = homozygous recessive genotype
* P2 or 2PQ =Dominant Phenotype
* Q2 = Recessive phenotype

5. Hardy-Weinberg equilibrium Allele Frequency in non-changing populations
Must have all Five conditions
1. no natural selection
2. Completely random mating
3. no mutations
4. Large population size
5. no migration (in or out of the population)
When a population is not evolving the allele frequencies are not changing= genetic equilibrium.

6. Examples- yes, you should have these in your notes 
A population of rabbits may be brown or white (the recessive phenotype). Brown rabbits have the genotype BB or heterozygous. White rabbits are homozygous recessive. The frequency of the homozygous recessive genotype is .35.
What is the frequency of the recessive allele?
What is the frequency of the dominant allele?
What is the frequency of heterozygous rabbits?

7. Moths Example
In a population of peppered moths, 30% of the population shows the recessive phenotype of white.
Which of the variables does 30% represent?
Given this information, what is the frequency of recessive alleles in the population (q)?
What is the value of p? How do you know?
If this population had 1000 moths. How many moths would be Homozygous dominant? Heterozygous? Homozygous recessive?

8. Rh protein example
In the US, 27% of the population has Rh negative blood, which is a recessive trait. If the student population of lincoln High School was 2,000, how many students would you expect for each of the three possible genotypes? Find q first.

9. Video: Sickle Cell Disease
Answer the 3 questions on the board in your notes

10. Evolution: Change of allele frequency in a population over time
Studying how allele frequencies change in a population over time= studying how the population is evolving
Non- hardy Weinberg : 5 causes of evolution *Begins by change in allele frequency*
1. Small populations
2. non-random mating
3. mutation occurs
4. migration (new genes in or loss of genetic diversity)
5. natural selection acts on population

11. 1. Small population size = genetic drift
Genetic drift: Elimination or drastic change in allele frequencies due to small population size
Random events that eliminate genes from a Small population

12. Bottleneck Effect
When a populations size is dramatically reduced for at least one full generation
leaving small population of survivors chosen by chance, NOT genetic fitness to survive
Examples:
Human Caused: Blue Whale
Natural: Forest Fire, Tsunami, disease etc….

13. Founder Effect
Reduced genetic diversity when a small group separates from larger population
Example:  Dutch settlers in South Africa have higher instance of Huntington's because original settling population had high occurrence.

14. 2. non-random mating
Sexual selection – Individuals compete to mate and pass on their genes
WOWSERS! What a HOTTIE!!!
Intersexual Selection= One sex chooses the most attractive mate of the opposite sex
NO WAY DUDE!! SHE”S MINE!
That’s my Girlfriend!!
Intrasexual Selection=
Same sex individuals “battle” for mates

15. Mating systems can be either:
Monogamous= One male and one female paired for at least one breeding season if not longer
Polygynous= One male mates with several females
Polyandrous= One female mates with several males (by far the most rare)

16. 3. Mutations occur: Mutation = change in DNA
Either random or caused by environmental factors
Mutations can be beneficial, neutral, or harmful for the organism. Beneficial ones stick around, harmful do not!

17. 4. Migration occurs
Individuals and their genes moving from one population to another.
Example: Pollen being blown to a new destination, fish up a new stream, etc.
This is called “gene flow” and creates more genetic diversity

18. Emigration= leaving original population
Immigration= entering a new population

19. 5. Natural selection occurs
Nature selects who survives to pass on genes
“Survival of the Fittest” = struggle for survival
Best genes=best traits = survival and offspring= FITTEST
“FITNESS” in Evolution is not about being being in shape

20. Fitness (Survival of the Fittest)
The organism that is best suited to its current environment will live AND pass on its genes
Example:
The brown beetles have a greater fitness relative to the green beetles.

21. 3 Types of Natural Selection
Charles Darwin– Described Natural selection After observing nature on his “Voyage of The Beagle in 1830’s”
Published “Origin of Species” in 1859
Famous examples: Galapagos finches and torotoises
3 Types of Natural Selection
Directional Selection
Stabilizing Selection
Disruptive Selection

22. 3 Types of Natural Selection
1. Directional Selection – Environment causes an increase in the number of individuals with the trait at one end of the curve.

23. 3 Types of Natural Selection
Stabilizing Selection-Individuals in the center of the curve are more fit and thus the curve narrows

24. 3 Types of Natural Selection
3. Disruptive Selection-Individuals at the ends of the curve are more fit than the ones in the middle causing two curves to form and possible new species to form.

25. Formation of New Species=“Speciation”
Species= group of organisms that interbreed and produce fertile offspring
Created by evolution (Remember 5 causes!)
Boundaries between species can sometimes be unclear
Can also be determined by DNA, morphology, and niche
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

26. Central Concept of Evolution….
All life on earth shares a common ancestor

29. Evidence for Evolution:
Paleontology- fossil record shows change over time (depth=time)
Biogeography- similar species live near each other

30. Evidence for Evolution:
Genetics- similar species have more similar genes in common. We can see relation through DNA
Embryology- an embryo displays its ancestral past as it develops

31. Evidence for Evolution:
Morphology- (shape) shows species adapt ancestral structures for new uses
Homologous structures-from the SAME ancestral structure
Analagous structures- adapted for same purpose but not from the same ancestral structure (ex.- wings on moth, bird, bat