ANSC 4395-Breeding & Genetics
FINAL Exam
Simply-Inherited Traits: - -Traits affected by only a few genes
EX: Coat color, Horns
-Simply-inherited Traits:
-Qualitative or categorical - -Either/or expression
EX: Black or red, Horned or polled
-Simply-inherited Traits are rarely... - -quantitative (Measured with numbers
or continuous)
EX: White spotting in cats (1-9 numerical rating)
-Simply-inherited Traits are typically, affected very little by... - -environment
EX: Chocolate lab may bleach out if left in the sun, but there is no mistaking
it for a black or yellow lab
-Polygenic Traits: - -Affected by many genes with no gene having an
overriding influence
EX: Growth rate, Milk production, Ribeye area
-Polygenic Traits are typically... - -quantitative or continuous in expression
-Phenotypes are usually described by numbers
EX: Weaning weights, Milk yield, Ribeye Area
-Polygenic Traits are greatly influenced by... - -environment
-Lack of feed
-Heat/cold stress
-Training of quarter horses (speed)
-Some polygenic traits have categorical phenotypes, called what? - -
Threshold Traits
-Pregnancy (pregnant or not pregnant)
-Dystocia (1-5)
-Natural gait (trotter or pacer)
-Influenced by many genes but have an either/or result
, -Between simply-inherited and polygenic traits, which is more important? - -
Typically, polygenic traits
-Growth rate, fertility, milk production
-Traits that determine productivity and profitability
-Traits: Some markets are more sensitive to... - -simply-inherited traits
-Coat or feather color
-Polled
-Genetic defects are usually... - -simply-inherited
-Common Characteristics of Simply-inherited & Polygenic Traits: - --Both are
subject to the same Mendelian mechanisms (Laws of segregation &
independent assortment)
-Dominance and epistasis affect both
-Principles of selection and mating apply to both (attempt to increase the
frequencies of favorable alleles)
-Different Breeding Approaches-
Function of the number of genes involved: - --The more genes involved, the
more difficult it is to observe the effects of individual genes, and therefore
the less specific info we have about those genes
-More "noise" in equation
-When a few or one gene affects a trait, the effects of those genes are well
understood (EX: Color, Polled)
-What are test matings? - -Matings designed to reveal the genotype of an
individual for a small number of loci
-Simply-inherited traits
-Test Matings-
Polygenic traits: - -Polygenic traits have so many genes affecting them that
this is impossible
-Can not observe the effects of specific genes
-Have to characterize the net effect
-EX: Breeding Values, EPDs
-There are 3 general types of test matings to determine if an individual is
heterozygous: - --Mating to recessives
-Mating to heterozygotes
-Mating a sire to his daughters
-The method with the highest probability of detection is... - -mating to
recessives
-Probability of siring a recessive offspring is 1/2
FINAL Exam
Simply-Inherited Traits: - -Traits affected by only a few genes
EX: Coat color, Horns
-Simply-inherited Traits:
-Qualitative or categorical - -Either/or expression
EX: Black or red, Horned or polled
-Simply-inherited Traits are rarely... - -quantitative (Measured with numbers
or continuous)
EX: White spotting in cats (1-9 numerical rating)
-Simply-inherited Traits are typically, affected very little by... - -environment
EX: Chocolate lab may bleach out if left in the sun, but there is no mistaking
it for a black or yellow lab
-Polygenic Traits: - -Affected by many genes with no gene having an
overriding influence
EX: Growth rate, Milk production, Ribeye area
-Polygenic Traits are typically... - -quantitative or continuous in expression
-Phenotypes are usually described by numbers
EX: Weaning weights, Milk yield, Ribeye Area
-Polygenic Traits are greatly influenced by... - -environment
-Lack of feed
-Heat/cold stress
-Training of quarter horses (speed)
-Some polygenic traits have categorical phenotypes, called what? - -
Threshold Traits
-Pregnancy (pregnant or not pregnant)
-Dystocia (1-5)
-Natural gait (trotter or pacer)
-Influenced by many genes but have an either/or result
, -Between simply-inherited and polygenic traits, which is more important? - -
Typically, polygenic traits
-Growth rate, fertility, milk production
-Traits that determine productivity and profitability
-Traits: Some markets are more sensitive to... - -simply-inherited traits
-Coat or feather color
-Polled
-Genetic defects are usually... - -simply-inherited
-Common Characteristics of Simply-inherited & Polygenic Traits: - --Both are
subject to the same Mendelian mechanisms (Laws of segregation &
independent assortment)
-Dominance and epistasis affect both
-Principles of selection and mating apply to both (attempt to increase the
frequencies of favorable alleles)
-Different Breeding Approaches-
Function of the number of genes involved: - --The more genes involved, the
more difficult it is to observe the effects of individual genes, and therefore
the less specific info we have about those genes
-More "noise" in equation
-When a few or one gene affects a trait, the effects of those genes are well
understood (EX: Color, Polled)
-What are test matings? - -Matings designed to reveal the genotype of an
individual for a small number of loci
-Simply-inherited traits
-Test Matings-
Polygenic traits: - -Polygenic traits have so many genes affecting them that
this is impossible
-Can not observe the effects of specific genes
-Have to characterize the net effect
-EX: Breeding Values, EPDs
-There are 3 general types of test matings to determine if an individual is
heterozygous: - --Mating to recessives
-Mating to heterozygotes
-Mating a sire to his daughters
-The method with the highest probability of detection is... - -mating to
recessives
-Probability of siring a recessive offspring is 1/2
