1. Q.Q. 4/3/19
Within which level of biological organization is evolution occurring?
Organism
Ecosystem
Community
Population

2. Chapter 23- Population Genetics

3. Population Genetics and Evolution
Population- Localized group of individuals that are capable of interbreeding and producing fertile offspring

5. Key Terms:
Microevolution- The change in genetic makeup from generation to generation (Individuals are selected, populations EVOLVE!)
Modern Synthesis- Integration of many other fields of study into evolution (such as statistics, botany, etc…)
Gene Pool – ALL alleles at all loci of a population

7. Hardy-Weinberg Theorem
Frequency of alleles and genotypes in a population gene pool will remain CONSTANT from generation to generation- if ONLY Mendelian segregation and recombination of alleles are at work.
It would be a NON-EVOLVING POPULATION!
*Equilibrium = stays the same

8. Hardy- Weinberg Equilibrium- Genotypic frequencies can be predicted using the following formulas:

10. Hardy-Weinberg Equilibrium
IE- 500 wildflowers will have 1000 genes for color
CRCR = Red = 320 flowers x 2 =640 CR genes
CWCW = White = 20 flowers x 2 40 CW genes
CRCW = Pink = 160 flowers x 1= 160 CR genes, 160 x 1 CW genes

11. Hardy-Weinberg Equilibrium
CR = = CW = = 200
800/1000 = .8 = 80% = p /1000 = .2 = 20% = q
Statements that can now be made-
- 80% chance that a wildflower will carry CR
- 20% chance that a wildflower will carry CW

12. Determining Genotype frequencies using Hardy- Weinberg Equilibrium:
Chance of:
CR CR = .8 x .8 = OR CAN BE WRITTEN:
p x p = OR CAN BE WRITTEN:
p2 = .64
.64 = 64%

13. Hardy-Weinberg Equilibrium
CW CW = .2 x .2 = OR CAN BE WRITTEN:
q x q = OR CAN BE WRITTEN:
q2 = .04
.04 = 4%

14. Hardy-Weinberg Equilibrium
CWCR = .2 x .8 = .16 OR CAN BE WRITTEN: q x p = .16 = 16% CRCW = .8 x .2 = .16 OR CAN BE WRITTEN: p x q = .16 = 16% *same!

15. Hardy-Weinberg Equilibrium
Overall- p2 + 2pq + q2 = 1 (or 100%)

18. 5 Conditions required for Hardy- Weinberg Equilibrium:
1) Large population size
2) No gene flow between populations (no immigration/emigration of organisms within populations)
3) No mutations
4) Random mating (no selection for certain traits; i.e. coloring, patterns,etc)
5) No natural selection

19. *Do these conditions TRULY exist in any biological system?
NO, but conditions in a stable population are usually very close to these conditions and close enough to use Hardy- Weinberg Equilibrium as a tool to make predictions.

20. Example Problems:
IE- PKU is an inherited disorder that 1 in 10,000 people are born with (homozygous recessive). How many people in a this population would be carriers of PKU?
*REMEMBER: recessive = letter q so homozygous recessive = q2
q2 = 1/10,000 = .0001
To determine frequency- √.0001 = .01 = q (or 1% of population will have PKU allele)

21. p = 1 – q = .99 = p (or 99% of the population will carry the dominant allele) How many are carriers (heterozygous)??

22. Hardy-Weinberg Equilibrium
2pq = 2 x .99 x .01 = (or about 2% of the population will be heterozygous)

23. More H-W Practice Problems
Complete the last 2 word problems in your notes!

24. Changes in Gene Pools
Mutations that can cause changes 1- Point Mutations 2- Chromosomal Mutations

25. Change We can predict mutation rates, but NOT the actual mutation
Sexual recombination can cause change in a population

26. The three factors that alter allele frequency and cause the most evolutionary change are:
1) Natural Selection

27. 2 types of Genetic Drift:
The three factors that alter allele frequency and cause the most evolutionary change are:
2) Genetic Drift- Fluctuation in allele frequency based on a finite population size and chance.
2 types of Genetic Drift:
Bottleneck Effect- Sudden change in environment reduces size and only several individuals survive. These individuals may not be reflective of the original gene pool.

29. 2nd type of Genetic Drift (continued)
Founder Effect- Individuals become isolated from a population and establish a new population.

30. The three factors that alter allele frequency and cause the most evolutionary change are:
3) Gene Flow- Genetic additions/subtractions from a population resulting in a “movement” of a trait. IE- Pollen from one island flower moves to another island and spreads its genes to that new location. *immigration/emigration

31. More about natural selection:
Genetic variation-
Phenotypic polymorphism- two or more distinct morphs represented in highly notable frequencies
Average heterozygosity- Average heterozygous loci in a population.
IE- 1,920 of 13,700 of a certain loci are heterozygous = 17%

32. More about natural selection:
Geographic variation- Differences in gene pools of separated populations (perhaps separated by a mountain range)
Clines- Graduated change in a trait along a geographic axis

34. Fitness
Fitness- The contribution an individual makes to the gene pool of the next generation.
- Usually ranges from 0  1
- If an individual has a fitness of “0” they do not pass on any traits (no reproduction)
- If an individual has a fitness of “1” the entire next generation is composed entirely of those individuals genes/traits

35. Selection
Selection-
1) Directional Selection- Environmental change or a migration shifts the frequency curve
2) Disruptive Selection- Favors variants and removes intermediates
3) Stabilizing Selection- Removes extreme variants and favors intermediates

37. Sexual Selection
Sexual Selection- Natural selection for mating success
Intrasexual- IE- Males fighting males for the right to breed with females
Intersexual- Mate choice. Usually female choosing the “best” male

38. Sexual Reproduction
Sexual Reproduction is “inferior” to asexual reproduction.
- Asexual individual population will outgrow that of the sexual individuals.