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Genetics > Principles of Selection > Flashcards

Principles of Selection Flashcards

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Biology 101 flashcards
1
Q

is the art and science of the genetic improvement of farm animals.

A

Animal Breeding

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2
Q

choosing some animals as parents of the next generation of animals.

A

Selection

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3
Q

removal of inferior animals

A

Culling

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4
Q

What is the basis of animal breeding is ?

A

correct selection of breeding animals for mating

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5
Q

obtained as a regression of a phenotypic deviation

A

Estimation of Breeding Value

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6
Q

records deviated from a mean

A

Phenotypic Deviation

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7
Q

Breeding Value in the phenotypic deviations

A

Regression

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8
Q

is the proportion of the phenotypic variance that is due to genetic effects including additive, dominance and epistasis:

A

Heritability in the broad sense (H2)

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9
Q

is the proportion of the phenotypic variance that is due to additive genetic effects only.

A

Heritability in the Narrow Sense (h2)

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10
Q

What does the heritability in the narrow sense measure?

It measures the degree to which the offspring —-

If a trait has a large heritability, animals with high performance for the trait will produce offspring with —- ———

A

resemble their parents in performance for a trait.

High Performance

If a trait has a small heritability, performance records of parents reveal —— —— about the performance of their offspring

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11
Q

Traits with low heritability ranges from??

A

h2 < 0.20

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12
Q

Moderately heritable traits ranges from ??

A

h2 0.2 to 0.4

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13
Q

Highly heritable traits ranges from?

A

h2 > 0.40

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14
Q

Traits with low heritability (h2 < 0.20): charactersitics:

A

• reproductive traits

• longevity or productive live ( about 0.10)

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15
Q

Moderately heritable traits (h2 of 0.2 to 0.4): Characteristics: ll

A

• Milk yield, fat yield and protein yield (0.25-0.35)
• Birth weight
• Weaning weight
• Yearling weight

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16
Q

Highly heritable traits (h2> 0.4):

Characteristics:

A

• Carcass traits and traits related to skeletal dimensions like mature body weight

• Fat and protein% in milk.

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17
Q

animals are selected based on their ancestors, where the performance of these ancestors is known then a useful selection can often be made.

A

Pedigree Selection

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18
Q

the breeding value of each individual is assessed on the average performance of a random sample of its progeny, and animals are selected or culled based on this progeny performance

A

Progeny Testing

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19
Q

any animals unsatisfactorily for the character being selectedcan be culled before breeding is commenced.

A

Mass or Individual Selection

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20
Q

selection based on theperformance of nearby relatives

A

Family Selection

21
Q

selection is made for one trait or character at a timeuntil it is improved, then for a second trait and so on.

A

Tandem Selection

22
Q

a method where minimum standards of performanceare established for each trait in the criteria. Anyanimal not satisfying the minimum standard for alltraits is culled.

A

Independent Culling Level

23
Q

Each character is given a score and scores for all characters being considered are added together. Those with the poorest total scores would be culled.

A

Selection Index

24
Q

breeding of two or more different breed of animal.

A

Crossbreeding

25
Q

means that breeding of animal with the same breed.

A

Purebreeding

26
Q

Mating between animals, which are more closely related to each other than the average relationship between all individuals in the population.

A

Inbreeding

27
Q

1st mating: A x B

1st generation: ½ A ½ B

2nd mating A x ½ A ½ B

2nd generation ¾ A ¼ B

A

Inbreeding

28
Q

Mild form of inbreeding. Mating of cousins, grandparent to grand offspring or half-brother to half sister.

A

Linebreeding

29
Q

Example: A is ♀; B & C is ♂
1st mating: A x B A x C
1st generation: ½ A ½ B ½ A ½ C
2nd mating ½ A ½ B x ½ A ½ C
2nd generation ½ A ¼ B ¼ C

A

Linebreeding

30
Q

Mating of animals of different families within the same breed that are not closely related. (For at least the first four to six generation.

A

Outcrossing

31
Q

is the mating of two animals from different breeds.

A

Crossbreeding

32
Q

The increased level of performance of the offspring as to compare to the average of the parental type is known as

A

Heterosis or Hybrid Vigor

33
Q

There is a ——– relationship between heterosis and heritability:

the traits that demonstrate the most hybrid vigor are those that show the ——- heritability.

A

Reciprocal

Lowest heritability

34
Q

Crossbreeding can be used to:

A

•Develop new breeds
•Upgrade local breeds

35
Q

Two different populations can be crossed with each other to produce an F1 generation which is used only for production purposes and not for breeding.

A

Single Two-Way Cross

36
Q

This system relies on the crossing of two breeds A and B to produce a female excelling in maternal performance in a particular environment and the use of a third breed to produced the ideal animal for the market product.

A

Three Way Cross

37
Q

Populations A and B are first crossedwith each other, and so are C and D to obtain the F1generation A x B and C x D. These are then crossedtogether to produce the double hybrids AB x CD. It isnecessary to maintain only relatively small number ofanimals of the lines A, B, C, and D.

A

Four way cross

38
Q

The F1 females are back crossed to oneof the parental populations. For example, A x B females are mated with A or B to produce an offspring AB x A or AB x B.

A

Backcross

39
Q

This method takes fulladvantage of heterosis in the F1 females and half ofthe potential heterosis in the offspring.

A

Backcross

40
Q

In which males of each of the two breeds involved are used alternately; this system hasthe advantages over the two-way cross, in that thecrossbreed females can be used for breeding.

A

Two-way rotational cross

41
Q

A x B —— AB
First mating : A x AB
Second mating: B x AB
Third mating: A x AB

A

Two-way rotational cross

42
Q

In which males of each of the three breeds are used in turn; cross bred females produced can be used for breeding.

A

Three-way rotational cross

43
Q

A x B x C ——- ABC
First mating : A x ABC
Second mating: B x ABC
Third mating: C x ABC

A

Three way rotational cross

44
Q

Selection for Quantitative Traits

A

Estimate merit (BV’s)
Determine accuracy of estimation
Predict response to selection

45
Q

Methods of Selection

A

Tandem Selection
Independent Culling Level
Selection Index

46
Q

Aids to Selection

A

Pedigree Selection
Progeny testing
Mass or Individual Selection
Family Selection

47
Q

Mating Systems

A

Cross breeding and Purebreeding

48
Q

Types of Crossbreeding

A

Inbreeding
Linebreeding
Outcrossing

49
Q

Methods of Crossbreedings

A

Single two way Crosses
Three way cross
Four way cross
Back cross
Two way rotational cross
Three way rotational cross

Genetics (8 decks)

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