exam 2 Flashcards
(219 cards)
1
Q
what happens to diploid organisms?
A
the recombine (sex) and create new genotypes
2
Q
what are the two equations for HW
A
p+q=1
p^2+2pq+q^2=1
3
Q
what is the equation for a HWE with 3 alleles
A
p^2+q^2+r^2+2pq+2pr+2qr
4
Q
what is the equation for a HWE with n alleles
A
p^2+q^2+r^2+s^2+t^2+N^2+2pq+2pr+2ps+2pt+2pN+2qr+2qs+2qt+2qN+2rs+2rt+2rN+2st+2sN+2tN
5
Q
what is the HWE equation for a polyploidy individual
A
(p+q)^c
6
Q
what does c represent in the polyploid equation
A
number of chromosomes
7
Q
what is the total number of alleles in a diploid organism
A
the total number of individuals x2
8
Q
the total number of dominate alleles at a locus is _ alleles for each homozygote and _ for each heterozygote. the same goes for the _____________ genotype.
A
2; 1; recessive
9
Q
is a population like this: AA=0.64, Aa=0.32, aa=0; in HWE?
A
no, because it does not equal 1
10
Q
true or false: some loci can be out of HWE while other loci are in HWE
A
true
11
Q
what are qualitative traits? give examples
A
traits that are affected by a few genes that can be categorized, without environmental effects
coat color, horns, genetic defects
12
Q
what are two types of qualitative genetic defects?
A
spider syndrome (splayed legs) and curly calf syndrome (calf curls).
13
Q
what can be used to determine genotypical diseases
A
genetic testing
14
Q
define polygenic (quantitative) traits. give examples
A
traits affected by many genes; no single gene has an overriding effect, and it is affected by the environment
milk production, growth rate, birthweight, dystocia
15
Q
how would one describe polygenic traits
A
with numbers and ranges
16
Q
P (phenotype) = what?
A
μ+G+E
17
Q
what does P stand for in P=μ+G+E
A
the phenotypic value for a given trait
18
Q
what does μ stand for in P=μ+G+E
A
the population mean phenotypes value for the trait of all animals in the population
19
Q
what does G stand for in P=μ+G+E
A
the genotypic value of the animal for the trait
20
Q
what does E stand for in V= P=μ+G+E
A
effect of environmental factors on the phenotype of animal
21
Q
G+E=
A
0
22
Q
define genotypic value
A
the overall effect of all the genes carried by the animal for a specific trait
23
Q
is genotypic value measurable?
A
not directly
24
Q
what makes up the genotypic value
A
the breeding value and gene combo value
25
define breeding value
part of the genotypic value that can be transmitted to offspring from parents
26
what makes up BV?
it is the sum of effects on individual genes
27
define considered parental value
value of an individual as a contributor of genes for the next generation
28
BV must be estimated for each __________ before parents are chosen
individual
29
P=
μ+BV+GCV+E
30
what are quantitative traits in beef cattle
carcass yield
growth traits
reproduction traits
31
describe carcass traits
IMF
fat thickness
ribeye area
32
give examples of growth traits
feed efficiency
birth weight
weaning weight
yearly weight
average daily gains
33
describe reproduction traits
scrotum circumference
heifer pregnancy
1st service conception
rebreeding rate
34
describe the quantitative traits in dairy cattle
milk yield
milk components (fat% and protein %)
type trait (udder depth; stature)
angularity
teat length
rear leg angularity
heifer pregnancy
FSC
days open (<90 days)
35
how many genes does an individual transmit it its offspring?
half of them
36
what are PD and TA? what animals are they used for?
PD- progeny difference; meat animals
TA- transmission ability; dairy animals
37
PD and TA are not ___________ ______________, so they can be predicted by ______________ ____.
directly measurable; performance data
38
what is EPD
estimated progeny difference
39
what is PTA
predicted transmission ability
40
EPD and PTA are actually the ____, just for __________ ________
same; different animals
41
define the BV of offspring
sum of the additive effects of the genes inherited from both parents
42
what is the equation for BV of offspring
(BVsire-BVdam)/2
43
define gene combination value
due to dominance and epistasis
not transported to offspring
44
which genes survive segregation and independent assortment
individual genes
45
what does PA stand for
performance potential
46
what is PA important for
repeating traits, like milk production
47
what does G do in respect to PA
remain with the animal its whole life
48
can E factors permanently affect PA?
yes
49
what does Ep stand for
permanent environment effects
50
what is an example of Ep
nutrition at early stages of life
permanent problem in the udder
51
what does Et stand for
temporary environmental effects
52
what is an example of Et?
forage quality
weather
management
53
what does PA=?
BV+GCV+Ep
54
can two individuals have the same BV? if so, how?
yes, if the have the same sire and dam
55
what is MPPA? what is it used for
most probable producing ability
used to predict the animals next record
56
what are the three steps for statistics and describe them
objectively evaluate numbers
whether or not an animal has the right genes
describe population
sample statistic
estimate unknown value
breeding value of sire and dam
57
define variation
the raw material a breeder available for herd improvement
58
what happens if there is no variation
there is no improvement
59
describe discontinuous variation
qualitative traits
few, discrete genes
phenotype is not greatly influenced by environment
60
describe continuous variation
quantitative traits
many genes
many small gradations
economically important traits
highly complex
61
define sample
a random group used to inference a population
62
define population parameter
numerical descriptive measure for a population
63
what does population parameter do
describes what makes one population different from another
64
define variance
spread around a mean
65
define sample statistic
numerical descriptive measure for a sample estimated from population parameter
66
define central tendency
graph where values cluster at midpoint and thin out around ends, the central position
67
what are the three measures of central tendencies
mean, median, mode
68
define x̄
sample mean
69
define μ
population mean
70
define Σ
sum
71
define n
number of observations in the sample
72
x̄=?
(Σx)/n
73
define variance
a measure of distribution
deviation about the mean
74
S^2=?
Σ(x-x̄)^2/n-1
75
a homogenous population will have __________ variance
little
76
what are the four steps to compute variance
1. find the mean for each observation
2. square the answer
3. sum all answers together
4. divide by n-1
77
what does standard deviation depict
how much variation exists for a trait
78
define standard error
how accurate mean has been estimated
79
SE=?
SD/√n
80
define correlations
measures strength of relationship between two variables
81
what does correlation do?
determines if one trait of an animal is associated with another
82
what is the correlation coefficient
r
83
what is the range of correlation
-1 to 1
84
±0.1-0.2 is ___ correlation
low
85
±0.21-0.4 is _______ correlation
moderate
86
±0.41-0.99 is ____ correlation
high
87
0 is __ correlation
no
88
define significant correlation
high probability there is a real association between traits
89
what leads to genetic correlation
gene linkage and pleiotropy
90
true or false: correlation is unitless
true
91
in correlation, one trait does not...
determine another trait
92
there is no ___________ or _______________ variable in correlation
dependent, independent
93
define maternal calving
ease of sire's daughter giving birth
94
define direct calving
ease of cows impregnated by sire giving birth
95
r=?
(ΣXY-(ΣXΣY/N))/√(ΣX^2-(ΣX)^2/N)(ΣY^2-(ΣY)^2/N)
96
what are the three types of correlation
rp- phenotypic correlation
rg- genetic correlation
re- environmental correlation
97
define phenotypic correlation
measure of strength of relationship between performance in one trait and performance in another
98
define genetic correlation
measures strength of relationship between breeding value of one trait and breeding value for another
99
in genetic correlation selection of one trait...
leads to selection of another trait
100
define environmental correlation
measure of strength of relationship between environmental effects
101
define the regression coefficient
measures change in Y response over unit change in X
102
regression coefficient is a given ________ of values
range
103
regression can be __________ or ___________
positive, negative
104
regression is used to predict one _________ based on another
value
105
ŷ=?
a+bx
106
what is ŷ
predicted value of Y
107
what is ȳ
mean of y observations
108
what is a
y-axis intercept
109
what is b
regression coefficient
110
what is x
the number of observations
111
what is x̄
mean of x observations
112
what does a greater slope mean
a closer association between two traits
113
for observations ____ is better, but for variance degrees ____ is better
more; less
114
define regression
the average or expected change in Y over the unit change in X
115
true or false: regression is expressed in original units of measure
true
116
what is Byx
the regression of y and x
117
what is regression
the assumption of cause vs. effect
118
what is X
the cause/independent variable
119
what is Y
effect/dependent variable
120
when is regression used?
when predicting numerical value of one trait from phenotypic value of another
121
what are the two main types of mating systems
random and nonrandom
122
what are the 2 main strategies for genetic change
selection and mating systems
123
define selection
effects allelic frequencies
124
define mating systems
effects genotypic frequencies
125
describe selection
choosing parents for the next generation for gene contribution
126
what is the goal of selection
increase desired alleles and decreases undesired alleles
127
describe mating systems
choosing which males mate with which females with no further change in allele frequency
128
what does inbreeding do
increase homozygosity and inbreeding depression
129
what does outbreeding do
increases heterozygosity and hybrid vigor
130
define positive assertive mating
individuals that look alike to increase homozygosity
131
define negative assertive mating
individuals are not phenotypically similar to increase heterozygosity
132
what is genetic relationship based on
pedigree
133
define inbreeding coefficient
the probability that 2 alleles at a locus are identical by descent
134
define phenotypic similarity
mating males and females with close phenotypic resemblances
135
what is the goal of nonrandom mating
to alter genotypic frequencies
136
what is the goal of positive assertive mating
increase homozygosity
137
what is the goal of negative assertive mating
increase heterozygosity
138
true or false: the sire and dam are usually related in inbreeding
true
139
what does it mean if two closely related individuals are mated
the inbreeding will be severe
140
what is the inbreeding coefficient
Fx
141
what are pedigrees converted into
arrow diagrams
142
how many times can an individual appear in an arrow diagram
only once
143
what is a Mendelian segregation
when each arrow leads away from an individual
144
define common ancestor
common to one or more individuals in an arrow diagram, usually to sire and dam of offspring
145
what is IBD
identical by descent
146
what is IBS
identical by state
147
define line breeding
a less intense form of inbreeding for a particular trait
concentrates on genes from a common ancestor
148
what is line breeding used commonly in
the horse industry
149
what are the six effects of inbreeding
prepotency
expression of deleterious recessive alleles
inbreeding coefficient
tends to fix traits in a population
concentrates genes
increase probability of getting similar genes from ancestor
150
define prepotency
uniformness between offspring and parents
homozygosity
151
describe expression of deleterious recessive alleles
gives inbreeding a bad reputation
increases the expression of detrimental genes, does not create them
152
describe inbreeding coefficient
quantitative traits that decrease inbreed performance
153
describe polygenic traits and give examples
small individual effects on genes, but when added become detrimental
ex: repro, production, product quantity
154
what is the equation of Fx
Σ0.5^n1+n2+1(1+Fa)
155
define genetic relationship
the proportion of genes two individuals have in common
156
what is the range of the genetic relationship
0-1
157
what does Rxy represent
the relationship between x and y
158
Rxy=?
(Σ0.5^n+1(1+Fa))/√ ((1+Fx)(1+Fy))
159
define outbreeding
mating of individuals less closely related genetically than average
160
where is outbreeding used
in the commercial meat animal production
161
define within breeding
a crossing of inbred lines
162
where is within breeding used
the poultry industry
163
define grading up
mating purebred males with non purebred females in an attempt to make a purebred population
164
how do you find the A in grading up? the b?
divide the precent by 2 and add fifty; divide percent by two.
165
define crossbreeding
crossing different breeds
166
define specie cross
breeding closely related species
167
what does specie crosses increase?
hybrid vigor and heterosis
168
what do Angus and brahman produce
a combo of growth, carcass, hardiness and adaptability
169
outbreeding is the __________ of inbreeding
opposite
170
what does outbreeding do with deleterious alleles?
it masks them, not delete them
171
what is the phenotype in outbreeding
hybrid vigor and heterosis
172
define heterosis
superiority of many traits of the offspring from outbreeding
173
% heterosis=
(ave crossbred-ave purebred)/ave purebred x 100
174
crossbreds are...
superior and more productive
175
what should crossbreeding result in
a superior crossbred
176
what does outbreeding try to increase
merit
177
what is the goal of outbreeding
to improve crossbred animal, not the purebred
178
who uses crossbreeding most
commercial producers
179
crossbreds will have a greater ___ ________ _____ than the best average purebred
net economic merit
180
define breed complementation
combining desirable characteristics of 2+ breeds in an offspring
181
what are the characteristics of Angus
maturity, fertility, milk production, marbling
182
what create efficiency
breed complementation and heterosis
183
what does the degree of heterosis and complementarity depend on
genetic relationship of parents
h^2 and ability to measure a trait
184
the higher the h^2 the ________ the heterosis
lower
185
what is the general use of crossbreeding
the maximum production of offspring
186
describe commercial cow/calf crossbreeding
almost all commercial cows are crossbred
very common in beef
187
describe swine crossbreeding
crossing inbred lines to maximize repro and growth
188
define reciprocal recurrent selection
a system of selection for increasing the combining ability for 2+ lines that have demonstrated the combine well
189
define development of superior inbred lines
crossing more genetically diverse lines of two breeds
190
define gca
general combining ability
191
define sca
specific combining ability
192
what is the net result of crossbreeding
development of genetically diverse inbred lines
better-performing crossbred offspring with greater heterosis
lines can cross with inbred lines
193
describe poultry crossbreeding
meat breeds are crossed for growth rates
194
describe dairy crossbreeding
within breeds, not between
195
what are development breeds used for
specific purposes and market
196
what does hybrid vigor produce in dairy cows
increased fertility
increased health and survivability
197
why is heterosis low in wool sheep
because the h^2 is high
198
what are the systems of crossbreeding (5 steps)
define objectives
breeds
herd size
implementation cost vs expected return
nothing is free
199
define objectives
traits of interest and complementarity
200
describe breeds
compatibility and availability
201
describe herd size
larger is better, but more complicated
202
describe implementation cost vs expected return
if making money using a certain system, why change it?
crossbreeds can be more expensive than purebreds
203
describe nothing is free
increased performance will require more feed/nutrients
204
what are swine categorizable for?
maternal and paternal
205
what are maternal swine breeds
yorkshire, landrace, and chester white
206
what are paternal swine breeds
duroc, hampshire, spots
207
what is the goal of crossbreeding
to increase heterosis
208
what are the three main types of crossbreeding
terminal
rotational
rotaterminal
209
describe terminal crossbreeding
all offspring are sold to market
offspring are uniform
210
describe rotational crossbreeding
rotates between 2-4 breeds
keep offspring
no uniformity
211
what is a downside to rotational
all animals will be crossbred at some point
212
describe rotaterminal
mix of rotation and terminal
some offspring are kept, some are sold
males produce good maternal females
213
what is the major genetic limitation of terminal
there is no benefit from maternal heterosis
214
what is the major management limitation of terminal
female replacements must be purchased
215
describe a three breed terminal cross
two maternal breeds create F1
chosen for growth and carcass traits
216
F1 is ___________ ____________ to the two parent breeds
genetically superior
217
what are maternal traits
adaptability to environment
high reproductive merit
milk production
mothering ability
218
rotational cross breeding does not…
benefit from maximum potential heterosis
219
why are 4 breed rotations better than 3 breed rotations? why are they worse?
they retain heterosis; it is more complex
