MBG 3060 FINAL QUESTIONS AND ANSWERS
What does the Fx value tell us? - Answers - If we were to pick a random locus in
individual x's genome, ____ of individual x's genome is homozygous for alleles inherited
from the common ancestors OR x/x loci that are are randomly picked will be
homozygous as a result of inheriting an allele in common from the common ancestor(s)
OR if we pick a locus at random in individual x's genome and genotype it there is an
____ chance that the locus will be homozygous for alleles inherited from common
ancestor(s).
How does an increase in inbreeding and relatedness affect the variability we would see
due to over-dominance? - Answers - The variability would decrease because the
proportion of heterozygous individuals would decrease and those individuals have the
largest expression of phenotype.
How would an increase in inbreeding and relatedness affect the variability we would see
due to incomplete dominance? - Answers - The variability would decrease somewhat
because the proportion of heterozygous individuals would decrease and those
individuals have a phenotype closer to one of the homozygotes.
How would an increase in inbreeding and relatedness affect the variability we would see
due to co-dominance? - Answers - The variability would be largely unaffected because
the proportion of heterozygous individuals would decrease and those individuals have a
phenotype between the homozygotes.
How would an increase in inbreeding and relatedness affect the variability we see due
to epistasis? - Answers - The variability would increase or decrease somewhat or even
stay the same because the proportion of heterozygous individuals would decrease but
the epistatic interactions could occur amongst any combination of genotypes.
How would an increase in inbreeding and relatedness affect the variability we see due
to pleiotropy? - Answers - The variability would increase or decrease somewhat or even
stay the same because the proportion of heterozygous individuals would decrease but
the pleiotropic interactions could occur amongst any combination of genotypes.
Phenotype of an individual depends upon what? - Answers - genotype + environment
Genotype is composed of what? - Answers - additive (inheritance) + dominance
(interactions between alleles) + interaction
Environment is composed of what? - Answers - permanent and temporary environment
What components are not passed on to the next generation? - Answers - dominance
and interaction genetic effects as well as permanent environment are specific to the
animal and are not passed on
, Why do geneticists focus on A? - Answers - Focus on A because this is what is passed
from generation to generation
What is the additive genetic component? - Answers - A measure of the sum of effects of
individual alleles
What is the dominance genetic component? - Answers - A measure of the combined
dominance effects of individual loci
What is the interaction genetic component? - Answers - A measure of the combined
interactions between loci (epistasis)
What is degree of dominance? - Answers - d/a
if d/a = 0 this is codominance
if d/a is between 0 and 1 this is incomplete dominance
if d/a is greater than 1 this is over dominance
What is broad sense heritability? - Answers - The proportion of total variance that is
genetic
What is narrow sense heritability? - Answers - The proportion of total variance that is
additive genetic and 1/2 is transmitted from parent to offspring.
Based on covariances among relatives. Can estimate it using either the regression of
offspring on parent or ANOVA.
What is covariance? - Answers - Covariance between relatives' records is the additive
relationship between the two multiplied by the additive genetic variance.
Calculating heritability: regression - Answers - -b is the regression coefficient
-Slope for regression of offspring on parent is 1/2(h^2) (2b = h^2)
-Slope for regression of offspring and midparent (both parents) is h^2 (b = h^2)
-Offspring midparent regression if preferred over offspring parent regression because it
includes more information
Why are we interested in heritability? - Answers - -It measures the proportion of total
variation that is additive genetic variation
-Indicates degree of genetic resemblance between relatives and generations
-Helps us define how much genetic change would result from selection
What is R? Does it have units? - Answers - R is the response to selection (deviation of
progeny from original population average). Yes it has units (same as phenotype)
What is S? Does it have units? - Answers - S is the selection differential (average of
selected parents deviated from the population mean). Yes it has units (same as
phenotype)
What does the Fx value tell us? - Answers - If we were to pick a random locus in
individual x's genome, ____ of individual x's genome is homozygous for alleles inherited
from the common ancestors OR x/x loci that are are randomly picked will be
homozygous as a result of inheriting an allele in common from the common ancestor(s)
OR if we pick a locus at random in individual x's genome and genotype it there is an
____ chance that the locus will be homozygous for alleles inherited from common
ancestor(s).
How does an increase in inbreeding and relatedness affect the variability we would see
due to over-dominance? - Answers - The variability would decrease because the
proportion of heterozygous individuals would decrease and those individuals have the
largest expression of phenotype.
How would an increase in inbreeding and relatedness affect the variability we would see
due to incomplete dominance? - Answers - The variability would decrease somewhat
because the proportion of heterozygous individuals would decrease and those
individuals have a phenotype closer to one of the homozygotes.
How would an increase in inbreeding and relatedness affect the variability we would see
due to co-dominance? - Answers - The variability would be largely unaffected because
the proportion of heterozygous individuals would decrease and those individuals have a
phenotype between the homozygotes.
How would an increase in inbreeding and relatedness affect the variability we see due
to epistasis? - Answers - The variability would increase or decrease somewhat or even
stay the same because the proportion of heterozygous individuals would decrease but
the epistatic interactions could occur amongst any combination of genotypes.
How would an increase in inbreeding and relatedness affect the variability we see due
to pleiotropy? - Answers - The variability would increase or decrease somewhat or even
stay the same because the proportion of heterozygous individuals would decrease but
the pleiotropic interactions could occur amongst any combination of genotypes.
Phenotype of an individual depends upon what? - Answers - genotype + environment
Genotype is composed of what? - Answers - additive (inheritance) + dominance
(interactions between alleles) + interaction
Environment is composed of what? - Answers - permanent and temporary environment
What components are not passed on to the next generation? - Answers - dominance
and interaction genetic effects as well as permanent environment are specific to the
animal and are not passed on
, Why do geneticists focus on A? - Answers - Focus on A because this is what is passed
from generation to generation
What is the additive genetic component? - Answers - A measure of the sum of effects of
individual alleles
What is the dominance genetic component? - Answers - A measure of the combined
dominance effects of individual loci
What is the interaction genetic component? - Answers - A measure of the combined
interactions between loci (epistasis)
What is degree of dominance? - Answers - d/a
if d/a = 0 this is codominance
if d/a is between 0 and 1 this is incomplete dominance
if d/a is greater than 1 this is over dominance
What is broad sense heritability? - Answers - The proportion of total variance that is
genetic
What is narrow sense heritability? - Answers - The proportion of total variance that is
additive genetic and 1/2 is transmitted from parent to offspring.
Based on covariances among relatives. Can estimate it using either the regression of
offspring on parent or ANOVA.
What is covariance? - Answers - Covariance between relatives' records is the additive
relationship between the two multiplied by the additive genetic variance.
Calculating heritability: regression - Answers - -b is the regression coefficient
-Slope for regression of offspring on parent is 1/2(h^2) (2b = h^2)
-Slope for regression of offspring and midparent (both parents) is h^2 (b = h^2)
-Offspring midparent regression if preferred over offspring parent regression because it
includes more information
Why are we interested in heritability? - Answers - -It measures the proportion of total
variation that is additive genetic variation
-Indicates degree of genetic resemblance between relatives and generations
-Helps us define how much genetic change would result from selection
What is R? Does it have units? - Answers - R is the response to selection (deviation of
progeny from original population average). Yes it has units (same as phenotype)
What is S? Does it have units? - Answers - S is the selection differential (average of
selected parents deviated from the population mean). Yes it has units (same as
phenotype)
