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Animal Breeding > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

What is inbreeding?

A

Mating of relatives more closely related than the average of the population

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2
Q

What are some effects of inbreeding?

A

Increase homozygosity
Prepotency in inbreds
Expression of deleterious recessive alleles
Inbreeding depression

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3
Q

What increases homozygosity?

A

Number of common ancestors

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4
Q

What is a common ancestor?

A

An ancestor common to more than one individual

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5
Q

What is prepotency in inbreds?

A

Ability of an individual to produce progeny whose performance is the same as its own or is uniform

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6
Q

What does prepotency cause?

A

Fewer heterozygous loci

Cannot produce as many different gametes

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7
Q

Does inbreeding create genetic defects?

A

No, they must already be in the population

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8
Q

What does inbreeding do for deleterious recessive alleles?

A

Increases the likelihood of them becoming homozygous and expressing themselves

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9
Q

What is inbreeding depression?

A

Reverse hybrid vigor

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10
Q

What does inbreeding depression mean for gene combination value?

A

It’s poor

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11
Q

What is poor gene combination value a direct result of?

A

Increased homozygosity

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12
Q

What is homozygosity and heterozygosity like with increased inbreeding?

A

Increased homozygosity, decreased heterozygosity

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13
Q

What traits does hybrid vigor work on first?

A

Fitness

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14
Q

What is GCV and BV like with low heritability?

A

More GCV and less BV

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15
Q

What is GCV and BV like with high heritability?

A

Less GCV and more BV

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16
Q

What is the inbreeding coefficient?

A

Measure of the level of inbreeding in an individual

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17
Q

What does it mean if an individual is 25% inbred?

A

It means that at a given locus in the individual, the probability that the two genes at the locus are identical by descent is 25%

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18
Q

Know the formula for inbreeding coefficient and Wright’s coefficient of relationship

A

Know the formula for inbreeding coefficient and Wright’s coefficient of relationship

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19
Q

What are the 6 steps for calculating inbreeding and relationship coefficient using path method?

A
  1. Convert the pedigree to an arrow diagram in which each individual appears only once
  2. Locate common ancestors
  3. Locate inbred common ancestors and calculate the inbreeding
  4. Fill in the table
  5. Sum the last column
  6. Divide the sum
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20
Q

What is line breeding?

A

Mating of individuals within a particular line

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21
Q

What are 2 reasons to inbreed?

A

Increase uniformity

Create an opportunity for hybrid vigor–inbred line crossed with inbred line

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22
Q

What is outbreeding/outcrossing?

A

Mating of unrelated individuals

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23
Q

What does outbreeding do for homozygosity and heterozygosity?

A

Increase heterozygosity, decrease homozygosity

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24
Q

What are 3 effects of outbreeding?

A

Masking deleterious alleles
Hybrid vigor or heterosis
Breed complementarity

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25
Q

What does hybrid vigor increase?

A

GCV

Fitness traits

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26
Q

What is heterosis/hybrid vigor?

A

An increase in the performance if hybrids over that of purebreds, most noticeably in traits like fertility and survivability

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27
Q

How do you measure hybrid vigor?

A

The difference between the average performance of crossbreds and the average performance of their parent lines of breeds

28
Q

What is F1 hybrid vigor?

A

The amount of hybrid vigor attainable in first cross individuals
Maximum hybrid vigor

29
Q

Know equations 3, 4, 5, and 6 in notes

A

Know at equations 3, 4, 5, and 6 in notes

30
Q

What are some hybrid vigor estimates?

A

Individual (direct component)
Maternal
Paternal

31
Q

What is measuring heterosis levels doing?

A

Matching of unlike genes

32
Q

What is retained hybrid vigor?

A

Hybrid vigor remaining in later generations of hybrids

33
Q

What are general rules for retained hybrid vigor? (3)

A

Retained hybrid vigor is commonly expressed as a proportion of F1 vigor
Hybrid vigor displayed by two-breed F1 crosses is halved in the corresponding F2s
Mating of F2s to produce F3s will not diminish hybrid vigor–Hardy-Weinberg equilibrium

34
Q

What are the 7 criteria for evaluating different crossbreeding systems?

A 
Merit of component breeds
Hybrid vigor
Breed complementarity
Consistency of performance
Replacement considerations
Simplicity
Accuracy of genetic prediction
35
Q

What is the amount of hybrid vigor in progeny in a two-breed terminal crossbreeding system?

A

100%

36
Q

What is the amount of hybrid vigor in females in a three-breed terminal crossbreeding system?

A

100%

37
Q

What is the amount of hybrid vigor in progeny in a three-breed terminal crossbreeding system?

A

100%

38
Q

Look at the terminal crossbreeding chart

A

Look at the terminal crossbreeding chart

39
Q

What is the amount of hybrid vigor in progeny in a two-breed rotational crossbreeding system after 7 generations?

A

67%

40
Q

In a two-breed rotational crossbreeding system, what are the progeny females made of?

A

67% breed of sire

33% breed of maternal grandsire

41
Q

What is the amount of hybrid vigor in progeny in a three-breed rotational crossbreeding system after 7 generations?

A

86%

42
Q

In a three-breed rotational crossbreeding system, what are the progeny females made of?

A

57% breed of sire
29% breed of maternal grandsire
14% remaining breed

43
Q

Look at 2-breed and 3-breed rotational crosses

A

Look at 2-breed and 3-breed rotational crosses

44
Q

What is the amount of hybrid vigor in progeny in a two-breed rotational and terminal crossbreeding system after 7 generations?

A

67% in rotation

100% in terminal

45
Q

What is the amount of hybrid vigor in progeny in a three-breed rotational and terminal crossbreeding system after 7 generations?

A

86% in rotation

100% in terminal

46
Q

Look at 2-breed and 3-breed rotational and terminal crosses

A

Look at 2-breed and 3-breed rotational and terminal crosses

47
Q

What is the amount of hybrid vigor in progeny in a four-breed rotational crossbreeding system?

A

93%

48
Q

What is a sire rotation?

A

Rotate sire every 4th year

49
Q

How was selection done in the past?

A

Selection based on phenotypes

Selection based on genetic predictions

50
Q

What are 4 examples of technology used in animal breeding?

A

MOET
Cloning
Sexed semen
Split embryos

51
Q

What is MOET?

A

Multiple ovulation and embryo transfer

52
Q

What can MOET be used to do?

A

Increase numbers of offspring per female

53
Q

What happens in cloning?

A

Somatic tissue is taken from a female and cells are grown, then transferred to recipients to get the exact copies of the cloned individual

54
Q

What is accomplished with sexed semen?

A

Sex control

55
Q

How is sex control done?

A

X sperm produces female, Y sperm produces males

56
Q

How do split embryos work?

A

If there is a 16 cell embryo, 8 cells are put into one recipient and the other 8 are put into another

57
Q

What is some DNA technology now available to producers? (3)

A

Fingerprinting
Genetic markers
Gene transfer

58
Q

What is fingerprinting?

A

The occurrence of a fragment indicates it was received from one or both parents

59
Q

What are genetic markers?

A

Positions on a chromosome that can be identified

60
Q

How is selecting at the DNA level done? (3)

A

DNA fingerprinting
Identification of genetic defects
Marker-assisted selection

61
Q

What does marker assisted selection use?

A

Genetic markers to select animals for quantitative traits

62
Q

What should genetic markers be used in association with?

A

Measures of genetic merit to make the most genetic change

63
Q

Why do genetic markers not change very much in performance?

A

There are associated with one gene

64
Q

What is fingerprinting useful for?

A

Parental identification in multi-sire herds

65
Q

What should marker assisted selection be used with?

A

Quantitative measures

Animal Breeding (4 decks)

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