Exam 1 Flashcards
(125 cards)
1
Q
What is a trait?
A
An observable or measurable characteristic of an individual
2
Q
What is an example of observable traits?
A
Appearance (coat color, horned, frame size)
3
Q
What is an example of measurable traits?
A
Performance (weaning weight, yearling weight, scrotal circumference, milk yield, yield grade, quality grade)
4
Q
What is phenotype?
A
Observed category or measure of performance for a trait of an individual
5
Q
What are 2 examples of the difference between a trait and phenotype?
A
Phenotype: red Trait: coat color
Phenotype: 565 lbs Trait: weaning weight
6
Q
What is genotype?
A
Genetic makeup of an individual
7
Q
What do the letters in P=G+E mean?
A
Phenotype
Genotype
Environment
8
Q
What is biological type?
A
Similar genotypes for traits of interest
9
Q
When choosing the best animal, what makes up the system?
A
Genotype
Physical environment
Fixed resources and management
Economics
10
Q
What are interactions?
A
A relationship where the effects of one component depends on another component
11
Q
What is genotype by environment?
A
Different in performance between 2 or more genotype changes from environment to environment
12
Q
In order to look at a G x E interaction, what must there be?
A
At least 2 genotypes and 2 environments
13
Q
When looking at a graph, how do you know if there was an interaction?
A
If there was a swap in rank or change in magnitude
14
Q
What are breeds?
A
Race of animals within species that have a common origin and similar characteristics
15
Q
What are 4 examples of breeding objectives?
A
Carcass characteristics
Replacement females
Milk quality
Wool production
16
Q
What is a population?
A
Group of intermating individuals
17
Q
What are the 2 types of selection?
A
Natural
Artificial
18
Q
What is natural selection?
A
Survival of the fittest
19
Q
What is natural selection independent of?
A
Humans
20
Q
What is an example of natural selection?
A
Hyperkalemic periodic paralysis
Parasite resistance
21
Q
What is artificial selection?
A
Human control
22
Q
What are some examples of artificial selection
A
Replacement
Culling
23
Q
How is phenotypic selection done?
A
Through performance
24
Q
How do we select the best breeding value? (4)
A
Measure performance
Information on relatives
Progeny
Genetic predictions
25
What is breeding value?
Value of the animal genetically and how it contributes in breeding
26
What are polygenic traits?
Traits made of many genes
27
What are simply-inherited traits?
Traits made of few genes
28
What are different matings and mating systems? (4)
Complementarity
Hybrid vigor/heterosis
Related individuals
Corrective matings
29
What is complementarity considered to be?
The best of both worlds
30
What are examples hybrid vigor/heterosis? (3)
Lines
Breeds
Species
31
What are examples of why you would use corrective matings? (2)
Frame size
| Structure
32
How are quantitative traits measured?
By a bell curve
33
What are quantitative traits affected by?
Many genes
34
What is population mean denoted by?
μ
35
What is the sample mean?
Sum of all observations divided by sample size
36
What is variation?
How individuals vary for a particular trait in a population
37
What do variations in breeding values allow for?
Selection
38
What is variation described by?
Variance
| σ^2
39
What is standard deviation?
The average deviation from the mean
| σ
40
What percentage of the population does 1 standard deviation account for? 2? 3?
68%
95%
99%
41
Write the formula for variance. Check notes for answer equation 2
Write the formula for variance. Check notes for answer equation 2
42
How do you calculate standard deviation?
Square root of variance
43
What is covariation?
How 2 traits vary together
44
What are the 3 aspects of covariation?
Direction
Correlation
Regression
45
What are the 3 types of direction?
Positive covariation
Negative covariation
No covariation
46
What is positive covariation?
Positive deviations with positive deviations
47
What is negative covariation?
Positive deviations with negative deviations
48
What is zero covariation?
No pattern
49
Write the formula for covariance. Check notes for answer equation 3
Write the formula for covariance. Check notes for answer equation 3
50
What is correlation?
Strength of the relationship between 2 variables
51
What is the variable for correlation coefficient?
r_x,y
52
What are the 3 types of correlations?
Phenotypic correlations
Genetic correlations
Environmental correlations
53
Write the formula for correlation coefficients. Check notes for answer equation 4
Write the formula for correlation coefficients. Check notes for answer equation 4
54
How is the correlation coefficient interpreted?
There is a (weak, moderate, strong: positive, negative) correlation between variable x and variable y
55
What is regression?
The amount of change in a variable that can be expected for a given amount of change in another variable
56
What is the variable for regression coefficient?
b_y,x
57
Is b_y,x the same thing as b_x,y?
No
58
In the regression coefficient is y the dependent or independent variable? X?
Dependent
| Independent
59
How is the regression coefficient interpreted?
If x moves 1 unit, y moves _____ on average
60
Write the formula for regression coefficient. Check notes for answer equation 5
Write the formula for regression coefficient. Check notes for answer equation 5
61
What is the model for quantitative traits?
P = μ + BV + GCV+ E
62
Write down the formula for prediction. Check notes for answer equation 7
Write down the formula for prediction. Check notes for answer equation 7
63
How can you determine possible genotypes and phenotypes? (3)
Punnett square
Genotypic ratio
Phenotypic ratio
64
How do you calculate the number of possible gametes?
2^n where n is the number of loci that are heterozygous
65
How do you calculate the number of zygotes?
3^n x 2^m where n is the number of loci where both are heterozygous and m is the number of loci where only one parent is heterozygous
66
What are the different types dominance? (4)
Complete dominance
Partial dominance
Over dominance
No dominance
67
What is complete dominance?
When the heterozygote is the same as homozygous dominant
68
Draw complete dominance graph
Draw complete dominance graph
69
What is partial dominance?
When the heterozygote is intermediate to homozygous genotypes, but more closely resembles the dominant
70
Draw partial dominance graph
Draw partial dominance graph
71
What is over dominance?
When the heterozygote is outside of the range homozygous genotypes, but closely resembles dominant
72
Draw over dominance graph
Draw over dominance graph
73
What is no dominance?
When the heterozygote is midway between the homozygous genotypes
74
Draw no dominance graph
Draw no dominance graph
75
What is epistasis?
Interaction among genes at different loci
76
What is an example of epistasis?
Golden retriever
77
What are 3 types of sex-related inheritance?
Sex-linked
Sex-limited
Sex-influenced
78
What is sex-linked?
Inheritance located on sex chromosomes
79
What is sex-limited?
Phenotypic expression is limited, such as milk production–both carry the gene, but female expresses
80
What is sex-influenced?
Expression differs between male and females
81
What is gene or allelic frequency?
Frequency of a gene in a population
82
What is the equation for gene/allelic frequency?
p + q = 1
83
What is genotypic frequency?
Frequency of a particular one-locus in a population
84
What is the equation for genotypic frequency?
P + H + Q = 1
85
How can genotypic frequencies be changed?
Increase the frequency of favorable genes
86
What is the effect of inbreeding mating systems?
Increase homozygosity, decrease heterozygosity
87
What is the effect of outbreeding mating systems?
Increase heterozygosity, decrease homozygosity
88
How do you calculate new gene frequencies with genotypic frequencies?
```
p = P + 1/2(H)
q = Q + 1/2(H)
```
89
What is the Hardy-Weinburg Equilibrium?
In a large, random mating, population gene and genotypic frequencies remain constant from generation to generation in absence of selection, mutation, and migration
90
What is the formula for Hardy-Weinburg Equilibrium?
p^2 + 2pq + q^2
91
What are characteristics of simply inherited traits?
Either/or, categorical, quantitative
| Affected very little by environment
92
What are characteristics of polygenic traits?
All genes add together to produce performance
Quantitative, continuous
Affected by environment
93
What are threshold traits?
Polygenic traits that exhibit categorical phenotypes such as dystocia and fertility
94
What are the 2 different breeding approaches?
Simple
| Polygenic
95
What is the simple breeding approach like? (3)
Easy to identify genotypes
Effects of specific genes
Identify through test mating or test cross
96
What is the polygenic breeding approach like? (5)
```
More genes affecting a trait
More difficult to observe individual gene effects
Less info about those genes
Difficult to identify animal's genotype
Evaluate net effect
```
97
What is a one-locus case?
Selecting for particular phenotypes
98
What do test matings reveal?
Genotype of an individual for a small number of loci
99
What does the probability of an individual not being a carrier depend on?
What animals are being used for mating
| How many times to mate
100
What are 3 factors influencing effectiveness of selection?
Initial gene frequency
Fitness of gene in population
Degree of dominance
101
If the initial gene frequency is high or low, what is the change like?
Slow
102
If the initial gene frequency is medium, what is the change like?
Fast
103
Where does the fastest change occur at in no dominance?
Intermediate gene frequency
104
In complete dominance, what do you select against?
Dominant allele
105
Why do we see do many recessive genes for the genetic defects despite strong natural and artificial selection against them?
Because there are carriers and we have no idea if it's there unless we see it. The right mating must occur to see it
106
With simply inherited traits, it's it easy or hard to identify genotypes?
Easy
107
With polygenic traits, it's it easy or hard to identify genotypes?
Hard
108
Since it is hard to identify genotypes with polygenic traits, how can use select animals?
Breeding value
109
What is the basic model for quantitative traits represent by?
P = μ + BV + GCV + Ep + Et
110
What is BV the sum of?
Independent gene effect of the animal's genes for a particular trait
111
How much of the genetic combination do parent's transmit to one locus?
Half
112
What part of the genotypic value can be transmitted from parent to offspring?
Breeding value
113
How much of the breeding value is transmitted? What is this called?
Half
| Progeny difference/transmitting ability
114
What is the equation for progeny difference?
1/2 BV
115
What is breeding value sometimes called?
Additive genetic value/additive value
116
What is the BV of the offspring equal to?
1/2 BV sire and 1/2 BV dam
117
What does the average performance of the offspring value equal?
μ + 1/2 BV sire + 1/2 BV dam
118
What is genetic combination value?
Remaining portion of the value for a trait due to genetic combination effects (dominance and epistasis)
119
Can GCV be transmitted from offspring to parent?
No
120
What does genotypic value equal?
BV + GCV
121
What are repeated traits?
Traits for which individuals commonly have more than one performance record
122
What is producing ability?
Performance potential of an individual for a repeated trait
123
What are permeant effects?
Affect of an individual performance for a repeated trait
124
What are temporary traits?
Influence on a single performance record of an individual
125
What is producing ability made of?
Ep, BV, and GCV
