Exam 3 pt 3

Question 1

balancing selection

Answer 1

not evolving toward allele fixation or elimination (more of a flat bell curve)

Question 1

balacing selection

Answer 1

not evolving toward allele fixation or elimination (more of a flat bell curve)

Question 2

balancing selection occurs because of a

Answer 2

• heterozygote advantage
• negative frequency dependent selection

Question 3

selection coefficient

Answer 3

looks at the degree to which a genotype is selected against
s = 1 - w

Question 4

heterozygote advantage will reach equilibrium when

Answer 4

s_AAp = s_aap

Question 5

negative frequency dependent selection

Answer 5

rare individuals have a higher fitness than more common individuals
* selection always favors less numerous genotypes
* drives towards balance

Question 6

disruptive selection

Answer 6

favors survival of two or more different genetypes with different phenotypes

Question 7

disruptive selection typically acts on

Answer 7

traits determined by multiple genes

Question 8

disruptive selection is likely to occur

Answer 8

in populations with diverse/different enviroments

Question 9

stabalizing selction

Answer 9

extreme phenotypes are selected against

Question 10

stabalizing selection tends to

Answer 10

decrease genetic diversity
* elimination of alleles that cause variation in phenotypes

Question 11

genetic drift

Answer 11

random changes in allele frequencies due to random fluctuations

Question 12

genetic drift

Answer 12

random changes in allele frequencies due to random fluctuations

Question 13

over the long run, genetic drift

Answer 13

favors either the loss or the fixation of an allele

Question 14

_ populations have more chance of fixation due to genetic drift

Answer 14

smaller

Question 15

expected number of new mutations

Answer 15

= 2N mu

N - number of indi
mu - mutation rate

Question 16

a new mutation is more likely to occur in a

Answer 16

large population

Question 17

the probability of fixation is

Answer 17

the same as the initial allel frequency in the population

Question 18

when N is large

Answer 18

• higher chance of new mutations
• higher chance of mutations being eliminated

Question 19

when N is large

Answer 19

• higher chance of new mutations
• higher chance of mutations being eliminated

Question 20

when N is small

Answer 20

• lower chance of new mutation
• new mutatiosn have a larger chance of being fixed

Question 21

average number of generations to achieve fixation

Answer 21

t = 4N

Question 22

alelle fixation takes longer in

Answer 22

large populations

Question 23

bottle neck effect

Answer 23

population randomly eliminates genotypes, no selection, diversity goes down

could be due to a natural disaster

Question 24

founder effect

Answer 24

a small group of individuals seperates frrom a larger group and starts its own popiulation that all originate from that small group

Question 25

consequences of founder effect

Answer 25

* founding population has less genetic variation than original population * allelic frequencies of founder population differ from the original population

Question 26

gene flow

Answer 26

the transfer of alleles from donor population to recipient population

Question 27

consequences of bidirectional migration

Answer 27

1. reduces allel frequencies differences between populations 2. enhances genetic diversity within a population

Question 28

assortive mating

Answer 28

individuals do not mate randomly * positive: mate bc of similar phenotypes * negative: mate bc of dissimilar phenotypes

Question 29

inbreeding coefficient

Answer 29

probability that teo alleles for a given gene in an individual will be identical because of a common ancestor

Question 30

inbreeding coeficient

Answer 30

sum of (0.5)ⁿ(1 + F_a) | n = number of indiv in inbreed path Fa = breeding coef of common ancesto

Question 30

inbreeding coeficient

Answer 30

sum of (0.5)ⁿ(1 + F_a) | n = number of indiv in inbreed path Fa = breeding coef of common ancesto

Question 31

fixation (inbreeding) coefficient

Answer 31

probability that an allele will be fixed in the homozygouse condition

Question 32

the value of the fixation (inbreeding) coeff increases as

Answer 32

population size decreases

Question 33

frequency of genotypes in inbreeding

Answer 33

AA = p² + fpq Aa = 2pq(1-f) aa = q² + fpq

Question 34

inbreeding effects on gentype frequencies

Answer 34

hetrozygote goes down while homozygotes go up

Question 35

inbreeding depression

Answer 35

in natural populations, inbreeding lowers overall fitness

Question 36

For a quantitative trait that is polygenic, which of the following would tend to promote a continuum of phenotypes? * Increasing the number of genes that affect the trait * Decreasing the effects of environmental variation * Increasing the mutation rate

Answer 36

Increasing the number of genes that affect the trait

Question 37

variance is

Answer 37

* a measure of the variation around the mean * computed as a squared deviation

Question 38

a QTL is

Answer 38

a site on a chromosome where one or more genes affected quantitative traits are located

Question 39

a genotype–environment interaction.

Answer 39

two more more genotypes noto affected the same way

Question 40

In a population of humans, the correlation between height for fathers and their adult sons is 0.24. What is the narrow sense heritability for weight in this population? Note: hN2 = robs/rexp

Answer 40

0.48

Question 41

The mean weight of cows in a population is 520 kg. Animals with a mean weight of 540 kg are used as parents and produce offspring that have a mean weight of 535 kg. What is the narrow-sense heritability (hN2) for body weight in this population of cows? Note: hN2 = (Xo − X)/(Xp − X) Where X is the mean weight of the starting population Xo is the mean weight of the offspring Xp is the mean weight of the selected parents

Answer 41

0.75

Question 42

genotype enviroment association

Answer 42

certain genotypes found in a particular enviroment

Question 43

quantitative genetics

Answer 43

study of traits that can be described numerically and varies measurably

Question 44

frequency distribution

Answer 44

Quantitative traits do not naturally fall into a small number of discrete categories An alternative way to describe them is a frequency distribution * To construct a frequency distribution, the trait is divided arbitrarily into a number of discrete phenotypic categories

Question 45

Be able to do the following types of calculations: mean, variance, standard deviation, covariance, and correlation (see Section 28.2, Figure 28.2).

Answer 45

ope

Question 46

polygenic inheritance

Answer 46

transmission of traits that are governed by two or more genes

Question 47

if r > 0

Answer 47

as one factor increases, the other factors will increase with it

Question 48

r = 0

Answer 48

the two factors are not related

Question 49

r < 0

Answer 49

as one factor increases, the other will decreases

Question 50

An r value that is statistically significant need not imply a

Answer 50

cause-and-effect relationship

Question 51

quantitative trait locus

Answer 51

The location on a chromosome that harbors one or more genes that affect the outcome of a quantitative trait

Question 52

If VG is very high and VE is very low

Answer 52

Genetics is more important in promoting phenotypic variation

Question 53

If VG is very low and VE is very high

Answer 53

The environment causes much of the phenotypic variation

Question 54

phenotypic variance

Answer 54

sum of genotic variance and enviromental variance

Question 55

genotype-environment association

Answer 55

When certain genotypes are preferentially found in a particular environment

Question 56

heritability

Answer 56

the amount of phenotypic variation within a group of individuals that is due to genetic variation

Question 57

If all the phenotypic variation in a group was due to genetic variation * Heritability

Answer 57

would have a value of 1

Question 58

heribility value of 0

Answer 58

If all the phenotypic variation was due to environmental factors

Question 59

narrow sense heritability

Answer 59

The heritability of a trait due to the additive effects of alleles | = r obs / r exp

Question 60

selective breeding

Answer 60

the modification of phenotypes in plant and animal species of economic importance by human intervention

Question 61

selective breeding leads to

Answer 61

ppopulation becoming monomorphic

Question 62

selection limit

Answer 62

when the population starts becoming monomorphic, more selective breeding have no effect

Question 63

realized heritability

Answer 63

estimating narrow sense heritability | Xo - X / Xp - X

Question 64

realized heritability

Answer 64

estimating narrow sense heritability | Xo - X / Xp - X

Question 65

heterosis

Answer 65

when inbred strains are crossed to each other and the offspring are more vigorous than either parent