Chapter 20: Population genetics, evolution at the population, species, and molecular levels

Question 1

What is the definition of a population?

Answer 1

group of organisms of the same species living in the same geographical area

Question 2

What is the definition of the gene pool?

Answer 2

all alleles of all the genes present in a population

Question 3

Describe genotypic frequency

Answer 3

proportion of individuals in a population with a specific genotype

Question 4

describe allelic frequency

Answer 4

proportion of a particular allele in a population

Question 5

What does hardy-weinburg principle allow us to ask

Answer 5

What affects the frequencies of alleles in a population

Question 6

Describe the peppered moth phenomenon

Answer 6

wild type moths can blend into the lichened tree trunk?????????

Question 7

Describe the conditions that will determine if allelic frequencies will remain constant?

Answer 7

• population is so large that allelic variations do not occur by chance
• mating is random
  -all genotypes have equivalent fertility and viability
  ———natural selection does not occur
  -mutation does not occur
  -migration into or out of the population is absent
  -genetic drift is absent

Question 8

Describe the allelic equation

Answer 8

p + q = 1

P= frequency (f) of alleles = 1
p = (f) of 1st allele (dom)
q = (f) of 2nd allele (rec)

(homo/hetero doesnt matter)

Question 9

Describe the genotypic equation

Answer 9

p2 + 2pq + q2 = 1
p2 = pp = frequency of 1st homozygous genotype (dom)
2pq = frequency of heterozygous genotype
q2 = qq = frequency of 2nd homozygous genotype (rec)

Question 10

Describe how to solve a codominance problem?

Answer 10

MM, MN, NN, total = 100
Q = frequency of each allele

frequency of M allele = (MM x 2) + (MN) / 200
frequency of N allele = (NN x 2) + (MN) / 200

Question 11

describe how to solve a dominance problem?

Answer 11

Q = frequency of hetero and homozygous dominant genotypes?

% of species resulting from homozygous recessive allele
1: q^2 = (% in decimal form)
2: q = sqrt(q^2)
3: p = 1 - q
4: 2pq = heterozygous
5: p^2
6: p = sqrt(p^2) = homozygous

Question 12

describe how to solve an X- linkage problem?

Answer 12

Q = what is the expected frequency of carrier (heterozygous) females

1: q = fraction of affected (ex: 1/50)
2: p = 1 - q
3: 2pq = carrier (hetero)

Q= frequency of affected (homozygous) females?
1: q^2 = affected (homo)

Question 13

What are some factors that affect allele and genotypic frequencies?

Answer 13

• mutations
• genetic drift
  —-chance factors… changes in allele frequencies
  —-smaller populations

Question 14

What is the founder effect?

Answer 14

an example of genetic drift… small portion of population is separated

ex: church of the brethren

Question 15

Describe the bottleneck effect?

Answer 15

genetic drift… a portion of the population is gone

Question 16

Describe the case of the cheetahs?

Answer 16

Example of bottleneck effect, the cheetahs mating within groups that were cut off from the rest of the population
- were mating with close relatives… developed inbreeding depression

Question 17

Describe the case of the hapsburg jaw?

Answer 17

Another example of bottle necking…