Worksheet 22:
Population genetics answers
Supplemental Instruction
Iowa State University / Leader: / Courtney
Course: / Bio 211
Instructor: / Boury
Date: / 11/7/12

1) What is an allele frequency?

Frequency of an allele (A or a)g in the gene pool

#of Aa+ 2(A)/2(total)

2) What is a genotype frequency?

Frequency of a genotype(AA, Aa or aa) in the population

#of AA/total

3) Write the Hardy-Weinberg equation.

P2+2pq-q2=1

P+q=1

P2= genotype frequency of AA homozygotes p= allele frequency of A

Q2= genotype frequency of genotype frequency of aa homozygotes q= allele frequency of a

2pq= genotype frequency of Aa heterozygotes

4) Find the allele and genotype frequencies of the following example.

You have 300 Flowers, 189 are red (RR), 79 are pink (Rr), and 32 are white (rr)

Allele freq=

AA= 189+2(79)/2(300)=.63=A

1-.63=.37=a

genotype frequency

AA= 189/30063%

Aa= 79/300 26%

Aa= 32/30010%

5) You have 300 flowers 90 are white (rr). How many are red (RR) ad how many are pink (Rr)

90/300=30%

q2=.3  white (90 individuals)

q= .54

p=.46

p2=.20  red (60 individuals)

2(.54)(.46)=.50% pink (150 individuals)

6) What are the requirements for hardy Weinberg?

Very large population

Isolation of population

No net mutations

Random mating

No selective pressures

7) What are the types of genetic drift, explain each one.

Genetic drift is changes in the allelic frequency due to random chance. Favors fixation or loss of an allele

Founder effect- pioneers of the pop. Move to a new area and start a new population

Bottleneck effect mass die off and survivors are a new population

8) What is gene flow?

Movement into or out of a populations

9) Define fitness

The likelihood the genotype will contribute to the genepool of the next generation, as compared to other genotypes . measures reproductive success

AA=5 Aa=4 aa=1

Set the most successful at 100%

5/5=100% 4/5=80% 1/5=20%

10) Define assortative and disassortative mating.

assortative mating= individuals wth similar phenotypes are more likely to mate, increases the homozygotes

disassortative mating= dissimilar phenotypes mate preferentially, favors heterozygosity