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AGRI 21: Animal Breeding > Varitation > Flashcards

Varitation Flashcards

1
Q

another term for variation

A

differences

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2
Q

Basic types of variation

A

phenotypic variation and genetic variation

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3
Q

refers to the actual variation we observe among animals for each trait of interest

A

phenotypic variation

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4
Q

phenotypic variation

A

refers to the actual variation we observe among animals for each trait of interest

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5
Q

what we can measure or touch

bonus: give examples

A

phenotype

bonus: growth rate, backfat depth, number of pigs born in a litter

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6
Q

genes that make up an animal

A

genotype

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7
Q

True or False:

Genotype does not contribute to phenotype

A

False, genotype contributes to the phenoype but many other factors also contribute to the phenotype (feeding, management, housing, disease, and other environmental factors)

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8
Q

True or False:

observing the pheontype of an animal does not necessarily tell us much about its genotype

A

True

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9
Q

Modify: (Provide two answers)

Genetic variation is the appearance or performance of the animal

A

Phenotypic variation is the appearance or performance of the animal

Genetic variation is the genetic make-up of the animal

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10
Q

refers to the amount of variation that is controlled by genes

A

genetic variation

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11
Q

what determines the potential amount of genetic improvement that can be made in a given breed or strain?

A

genes that are passed on from parents to offspring and the amount of genetic variation

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12
Q

what are alleles?

A

different forms of the same gene

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13
Q

different forms of the same gene

A

alleles

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14
Q

traits that are controlled by alleles of a single gene

bonus: meaning?

A

categorical/qualitative genes

bonus: traits fall into clearly distinguishable categories (horned or not horned, black coat or red coat, etc.)

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15
Q

_______________ can easily be fixed in the population so that no further genetic variation exists.

clue: for example, purebred Black Angus cattle are all black and show no variation for color

A

categorical/qualitative traits

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16
Q

True or False:
Most economically important traits are qualitative

A

False, most economically important traits are quantitative

17
Q

quantitative traits (fall in categories / measured in a continuous scale)

bonus: give example

A

measured in a continuous scale

bonus: back fat, weaning weight, growth rate

18
Q

True or False:

quantitative traits are generally controlled by many genes

A

true

19
Q

__________________ are virtually impossible to eliminate genetic variation from a given population

bonus: why?

A

quantitative traits

bonus: because quantitative traits are generally controlled by many genes

20
Q

genetic variation is often attributed to different kinds of gene action

what gene actions?

A

additive gene action, dominance gene action, and epistatic gene action

21
Q

Differentiate phenotypic variation and genotypic variation

A

phenotypic variation
- refers to the actual variation observed among animals for each trait of interest
- appearance/performance of the animal

genetic variation
- refers to the amount of variation that is controlled by genes
- genetic make-up of an animal

22
Q

Differentiate qualitative and quantitative traits

A

Qualitative / Categorical traits
- controlled by alleles of a single gene
- falls into clearly distinguishable categories
- can be easily fixed in the population so that no further genetic variation exists

Quantitative traits
- most economically important traits
- controlled by many genes
- measured on a continuous scale
- virtually impossible to eliminate genetic variation from a given population

23
Q

Explain:

P = G + E

bonus: further expand the equation and explain

A

Genotype and environment (/ non-genetic factors) contribute to phenotype

bonus:
P = A + D + EG + E

genetic variation (hence, genotype) are often attributed to additive, dominace, and epistatic gene actions

24
Q

describes the summing up of effects of alleles of a gene and of effects of genes at a different chromosome locations to make up a trait

A

additive gene action

keywords to take note: sum and adding of effects of genes

25
Q

refers to one allele overriding or dominating another at the same locus

A

dominance gene action

keyword: override and ominance of one allele

26
Q

True or False:

dominance gene action is usually difficult to take advantage of in breeding programs and is often ignored except for a few single gene traits like coat colort

A

true

27
Q

refers to the interaction of different genes so that they tend to enhance or cancel each other out rather than adding together

A

epistatic gene action

28
Q

_____________ is the most important for genetic improvement since it can be influenced by selection programs

A

additive gene action

29
Q

true or false:
dominance gene action contributes the most of the genetic variation behind most of the economically important traits

A

false, additive genetic action

30
Q

differentiate additive, dominance, and epistatic gene action

A

Additive Gene Action
- describes the summing up of effects of alleles of a gene and of effects of genes at different chromosome locations to make up a trait
- most important for genetic improvement since it can be influenced by selection programs
- contributes most of the genetic varation behind most of the economiclly important traits

Dominance Gene Action
- refers to one allele overriding or dominating another at the same locus
- usually difficult to take advantage of in breeding programs and is often ignored except for few single gene traits

Epistatic Gene Action
- refers to th interaction of different genes so that they tend to enhance or cancel each other out rather than adding together

31
Q

ratio of genetic variation to phenotypic variation

A

heritability

32
Q

heritability tells us what proportion of the differences in performance we observe between animals is due to _________ which can be passed on from generation to generation; and the remaining proportion is due to _______________ which cannot be passed on from generation to generation.

A

gene action;

environmental and outside influences

33
Q

heritability is the ratio of genotypic variation to phenotypic variation

give the equation for heritability

A

h^2 = genetic variance / phenotypic variane

34
Q

heritability value range from _________

A

0 to 1 or 0% to 100%

35
Q

True or False:

low heritability value means that genes has low genetic control over the trait

bonus: meaning?

A

true

bonus: meaning trait is not easily heritable

36
Q

moderate value for heritability

A

0.3 - 0.5 (30% - 50%)

37
Q

given trait B and b

BB is _______ while Bb is _______

A

BB - homozygous

Bb - heterozygous

AGRI 21: Animal Breeding (5 decks)

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