Exam #3 24

Question 1

quantitative genetics

Answer 1

traits either continuous or discrete(discontinuous) but are controlled by numerous genes
-polygenic and strongly influenced by environment(multifactorial)

Question 2

discontinuous/discrete

Answer 2

qualitative: only a few easily distinguished phenotypes

- pea shape, either Tall or Dwarf

Question 3

continuous

Answer 3

quantitative: continuous range of phenotypes

- wide rage of human heights.

Question 4

threshold traits

Answer 4

quantitative bc involvement of many genes and strong influence of environment.
-either absent or there.

Question 5

meristic traits

Answer 5

quantitative

• measured in whole numbers
• litter size and bristle number

Question 6

additive genetic interaction

Answer 6

no dominance between alleles.
two or more genes= a single contribution to final phenotype
ex-wheat color

Question 7

covariance

Answer 7

relationships between on population variable (phenotype) and another.

Question 8

regression coefficient

Answer 8

slope of best fit line between two variables

-allows predicting of one variable if you know the other

Question 9

phenotypic variance

Answer 9

Vp=Vg+Ve+Vge

-generally both genetic and environmental working together.

Question 10

Vge

Answer 10

Genotypic environment interaction

-different genotypes react differently to changing environments

Question 11

heritability

Answer 11

proportion of phenotypic variance due to genetic variance

Question 12

H2

Answer 12

Broad sense heritability.
H2=Vg/Vp
gives us which proportion of the population phenotypic variance is due to variation in genotype in individuals
DOES NOT PREDICT OFFSPRING

Question 13

h2

Answer 13

narrow sense heritability
h2=Va/Vp
predicting inheritance of quantitative traits
????Vg=Va+Vd+Vl
CAN predict parent to offspring

Question 14

realized heritability

Answer 14

the amount of heritability actually observed in crosses

Question 15

estimating heritability needs

Answer 15

slope of parent to offspring regression line

response to selection

Question 16

slope of regression line estimates

Answer 16

h2

Question 17

if h2 is less than one

Answer 17

the regression coefficient is less than 1

Question 18

R

Answer 18

response to selection

R=h2xS

Question 19

S

Answer 19

selection differential
difference between the mean of the population and the means of the selected parents.
S= R/h2

Question 20

for selection to occur

Answer 20

• variation in a trait that is at least due partially to variation in genes
• genetic variation in the population under selection

Question 21

selection limits due to

Answer 21

• loss of additive genetic variance in response to selection

- fitness decrease due to a genetic correlated response

Question 22

QTL

Answer 22

quantitive trait locus

• a gene or chromosomal region that contributes to the expression of quantitative characteristics
• QTL mapping, Genome wide association studies