Breeding MCQ 1 Flashcards
BLUP
Co-discovered by Henderson
HW Equilibrium
p^2 + 2pq + q^2 = 1
First livestock domesticated
Sheep & goats
Genetic improvement
Genetic improvement is permanent and cumulative. Occurs when the genetic merit (BV of an animal) is improved through selection
Calculate accuracy (ACC)
A measure of strength between the true breeding value and the predicted breeding value
Crossbreeding
Mating of animals from two breeds.
Advantage - heterosis (hybrid vigour -> increased fertility, longevity, feed efficiency, disease resistance)
Genetic lag
When the farmed animals of a particular breed lag behind the breeding herd in terms of genetic merit
Non-additive gene (Gene Combination Value GCV)
Part of an individual’s genotypic value that is because of gene combinations (dominance and epistasis) and cannot be transmitted to their offspring
Recombination frequency
A measure of the linear distance between genes. It allows genes to be mapped
No dominance
Expression of the heterozygous is midway to the homozygous genotypes, eg. RR - red, rr - white, Rr- pink
Epistasis
An interaction of genes at different loci such that the expression of genes at one loci depends on alleles present at other loci
Mendelian Sampling
The random sampling of parental genes caused by segregation and independent assortment of genes during germ cell formation and by random selection of gametes in the formation of the embryo
Number of unique gametes
= 2^n
number of loci that are heterozygous
Number of unique zygotes
= 3^n x 2^m
n = both parents are heterozygous
m = one parent is heterozygous
Genotypic frequency
Relative frequency of a one-locus genotype in a population
p + q = ?
p + q = 1 (always!)
P =
homozygous dominant genotypic frequency (BB)
H =
Heterozygous genotypic frequency (Bb)
Q =
Homozygous recessive genotypic frequency (bb)
p + h + q = ?
p + h + q = 1 (always!)
Assumptions for HW Equilibrium
Large populations, organism is a diploid, reproduction is sexual, random mating, generations are non-overlapping, no migration, no mutation, equal fitness among genotypes, equal fertility among genotypes, equal gene frequencies between sexes
Random Genetic Drift
Change in frequency due to random chance in small populations
Large population to increase variation
Effective population (Ne)
Ne = 4NmNf/(Nm + Nf)
Mutation
Mutation rates are in the order of 1/25,000
Δq = pu - qv
u = mutation rate from A to a (dom to rec)
v = mutation rate from a to A (rec to dom)
4 ways to change gene frequencies
Random genetic drift
Mutation
Migration
Selection
% of 1, 2, & 3 standard deviations
1 std dev = 68%
2 std dev = 95%
3 std dev = 99.7%
The Bulmer Effect
A reduction in variation due to selection programme
The effect of selection of genetic variability
Threshold Traits
Discrete (qualitative) on phenotypic scale
Continuous (quantitative) on genetic scale
Contemporary group
A group of animals with equal opportunity to perform.
The environmental differences become negligible
Genetic correlation
Measure of the strength of relationship between breeding values in one trait and breeding values in another
Predicted Transmitting Ability (PTA)
PTA = 1/2 * EBV
Half an individuals breeding value
Heritability depends on…
Population specific factors, such as allele frequencies and variation due to environmental factors
Qualitative traits
Controlled by single gene
Quantitative traits
Controlled by several genes
Heritability (h^2)
σ^2a/σ^2p
Best way to combat random genetic drift
Increase population size
Migration
Movement of individuals into or out of a population
Q2-How many chromosomes do Cattle have?
(A) 39
(B) 19
(C) 23
(D) 30
D
Q3-The statement ‘modes of gene expression is different between males and females’ describes which of the following?
(A)Sex-limited inheritance
(B)Incomplete dominance
(C)Sex-Influenced Inheritance
(D)Mendelian Sampling
C
Q4-A sire’s five locus genotype is AaBBCcDdee. A dam’s genotype is
AABbCcDdEe. Considering juts these five loci how many unique zygotes can
be produced?
(A)45
(B) 88
(C)72
(D)23
C
Q6-At what age is a broiler chicken killed?
(A)56 days
(B)42 days
(C)28 days
(D)64 days
B
Q7-Which of the following is an assumption of the Hardy Weinberg
Equilibrium?
(A)No Random Mating
(B)No Mutation
(C)Small Populations
(D)Organism is haploid
B
Q8-Who was the ‘Father of Animal Husbandry’?
(A)Charles Darwin
(B)Carl Friedrich Gauss
(C)Robert Bakewell
(D)Gregor Mendel
C
Q9-Which of the following is not an environmental factor?
(A)Disease status
(B)Climate
(C)Number of animal s in the herd
(D)None of the above
D
Q10-Gene frequency can be changes by Mutation.
(A)True
(B)False
A
Q11-Which of the following is not a Spontaneous mutation?
(A)Black coat colour in dogs
(B)Carpet wool gene in sheep
(C)Boorola gene in sheep
(D)HYPP in horses
A
Q12-Milk yield, speed, lameness and somatic cell score are all examples of
what?
(A)Qualitative traits
(B)Quantitative traits
(C)Sex-linkage
(D)Environment
B
Q13-At the C locus in horses, chestnuts (sorrels) are CC, palominos are Cc and
cremellos are cc. In a herd of 28 horses there are 6 chestnuts, 13 palominos
and 9 cremellos. What is the gene frequency at the dominant C locus in this
herd?
(A)0.746
(B)0.334
(C)0.567
(D)0.446
D
Q14-At the C locus in horses, chestnuts (sorrels) are CC, palominos are Cc and cremellos are cc. In a herd of 28 horses there are 6 chestnuts, 13 palominos and 9 cremellos. What is the genotypic frequency for the cc genotype?
(A)0.1135
(B)0.7789
(C)0.3214
(D)0.665
C
