Lecture 10- Population genetics

Question 1

Requirements for natural selection to occur

Answer 1

• variation in traits
• traits vary in how the impact survival/ reproduction
• traits are heritable

Question 2

genetic variation

Answer 2

refers to the differences in genes or other DNA sequences among individuals

Question 3

phenotype

Answer 3

physical features expressed by the genotype

Question 4

Discrete traits

Answer 4

single gene determines phenotypic differences and can usually be classified on an either-or basis

Question 5

Quantitative traits

Answer 5

two or more genes usually vary the phenotype in gradations along a continuum

Question 6

Neutral variation

Answer 6

differences in DNA sequence that do not confer a selective advantage or disadvantage.

Question 7

synonymous mutations

Answer 7

change in the dna sequence that codes for amino acids but does not change the encoded AA

Question 8

Nonsynonymous mutation

Answer 8

change the protein sequences and are frequently subjected to natural selection

Question 9

what prevents natural selection from reducing genetic variation to only the favorable alleles?

Answer 9

• Recessive alleles hidden from selection i heterozygotes
• heterozygote advantage
• selection can preserve variation

Question 10

Sexual selection

Answer 10

individuals with certain inherited characteristics are more likely than others of the same sex to obtain mates

Question 11

intrasexual

Answer 11

individuals of one sex compete directly for mates of the opposite sex

Question 12

intersexual

Answer 12

individuals of one sex are choosy in selecting their mates from the other sex

Question 13

sexual dimorphism

Answer 13

a difference in secondary sexual characteristics between males and females

Question 14

frequency-dependent selection

Answer 14

fitness of a phenotype depends on how common it is in the population

Question 15

negative frequency dependent selection

Answer 15

rare genotypes have a fitness advantage

Question 16

positive frequency dependent selection

Answer 16

common genotypes have a fitness advantage

Question 17

relative fitness

Answer 17

contribution an individual makes to the gene pool of the next generation relative to the contributions of others

Question 18

relative fitness is determined by the

Answer 18

survival/ reproductive rate of a genotypic relative to the maximum survival/ reproductive rate of other genotypes

Question 19

Most fit genotype should always have a relative fitness of

Answer 19

1.0

Question 20

if reproductive rates are all equal (RF)

Answer 20

each survival rate divided by the highest survival rate

Question 21

If survival rates are all equal (RF)

Answer 21

each reproductive rate divided by the highest reproductive rate

Question 22

Selection coefficient (s)

Answer 22

the relative strength of selection acting against a genotype
- s= 1- w w= relative fitness

Question 23

selection coefficient of 0 means

Answer 23

genotype is not being selected against (strong)

Question 24

selection coeff of 1 means

Answer 24

total selection, individuals produce no viable offspring

Question 25

selection coeff of 0.1 means

Answer 25

individuals with that genotype produce offspring at 90% of the fittest genotype

Question 26

P (frequency of A) + q (frequency of a) =

Answer 26

1, this will always be true

Question 27

Hardy-Weinberg principle

Answer 27

predicts what genotype frequencies and allele frequencies will occur in the next generation

Question 28

the Hardy- Weinberg principle assumes evolution

Answer 28

is not occuring

Question 29

Assumptions of Hardy- Weinberg Equilibrium

Answer 29

1. NO selection
2. No mutation
3. No migration
4. Large population
5. random mating

Question 30

Gene pool

Answer 30

all of the alleles from all the gametes produced in each generation

Question 31

Calculate the frequency of alleles

Answer 31

[2(# homozygous individuals) + # of alleles from heterozygous individuals] / total # alleles

Question 32

After calculating p, how do you find q?

Answer 32

q= 1-p

Question 33

Calculate the expected frequency of
homozygous dominant

Answer 33

p^2

Question 34

Calculate the expected homozygous recessive

Answer 34

q^2

Question 35

Calculate the expected heterozygous frequency

Answer 35

2pq

Question 36

How to tell if a population is in HW equilibrium?

Answer 36

If the expected frequencies are equal to the observed frequencies.

Question 37

How to calculate the expected # of individuals for that genotype

Answer 37

Multiply the frequency by the total number of individuals

Question 38

Can you always calculate allele frequencies from genotype frequencies?

Answer 38

Yes you can because the genotype predicts the phenotype

Question 39

Can you always calculate genotype frequencies from allele frequencies?

Answer 39

sometimes, you can if the population is in HW equilibrium