# Shared Flashcard Set

## Details

Poultry Breeding Chapter 13
Poultry Breeding Chapter 13
51
Agriculture
04/09/2018

## Additional Agriculture Flashcards

Term
 2 properties of a trait of economic importance in a population
Definition
 1: heritability2: phenotypic variability
Term
 when genetic improvement is almost impossible
Definition
 When a trait is not heritable or has no variability
Term
 2 ways a breeder can change a population
Definition
 1. Choice of individuals used as parents through artificial selection.2. Control the way by which parents are mated (mating plan).
Term
 artificial selection
Definition
 Choice of individuals used as parents
Term
 mating plan
Definition
 Controlling the way by which parents are mated
Term
 response to selection
Definition
 The genetic change due to selection
Term
 Response to selection (R)
Definition
 the difference in mean phenotypic value between offspring of the selected parents and the whole parental generation before selection.
Term
 Selection differential (S)
Definition
 the mean value of the selected individuals selected as parents expressed as a deviation from the population mean.
Term
 how to calculate Response to selection (R)
Definition
 R = h2 * S h2 = heritability S = Selection differential
Term
 The selection differential can be predicted in advance when these 2 conditions are met
Definition
 1: The phenotypic value of the trait under selection is normally distributed.2: Selection is by truncation.
Term
 truncation
Definition
 individuals being chosen strictly in order of merit as judged by their phenotypic values
Term
 under the previously mentioned conditions, selection differential depends on...
Definition
 1: The proportion of the population selected, p 2: The phenotypic standard deviation of the trait, σp
Term
 standardized selection differential
Definition
 S / σP
Term
 how to calculate intensity of selection (i)
Definition
 i = S / σP S = i * σP
Term
 how to calculate Response to selection (R) when intensity of selection is factored in
Definition
 R = i h2 σP or R = i h σA or R = (i h σA) / L h = accuracy of selection L = generation interval
Term
 Response to Selection depends on
Definition
 1. Selection Intensity2. Heritability of the Trait3. Variability in the Trait
Term
 sources of correlation among traits
Definition
 -genetic factors-environmental factors
Term
 how to calculate CovP
Definition
 CovP = CovA + CovE
Term
 genetic cause of correlation
Definition
 mostly pleiotropic property of genes
Term
 Pleiotropy
Definition
 propensity of a gene to affect more than one trait
Term
 when the environment causes correlation among traits
Definition
 when two traits are influenced by the same differences in environmental conditions
Term
 direct response
Definition
 response to the selection of a particular trait, such as trait X
Term
 correlated response
Definition
 the changes you observe on a trait other than the one you selected for; in this case, observed for trait Y when you selected for trait X. it can go the other way around as well.
Term
 how to calculate direct response
Definition
 RX = i h2 σp = i h σA
Term
 how to calculate correlated response
Definition
 CRY = i hX hY rg σPY rg = genetic correlation between traits X and Y
Term
 Advantages of Indirect Selection
Definition
 1: Trait X is cheaper and easier to measure2: Trait X can be measured earlier in life3: Trait Y is sex-limited, but trait X can be measured in both sexes.4: A typical example would be carcass trait.
Term
 some things to be considered in the optimization of a breeding program
Definition
 -genetic variance-accuracy of selection-intensity of selection-generation interval-population size
Term
 Bulmer effect
Definition
 selection causing reduction of additive genetic variance in the parents
Term
 accuracy of selection
Definition
 the correlation between the selection criteria and the true breeding value for the breeding goal that is to be improved
Term
 when selection intensity is directly related to the number of animals selected
Definition
 When the distribution of a trait is normal and selection is by truncation
Term
 selection intensity vs. response to selection
Definition
 increased selection intensity improves response to selection
Term
 selection intensity can be limited by
Definition
 1: reproductive capacity of the selected individuals2: population size3: inbreeding
Term
 selection intensity vs. effective population size
Definition
 greater intensity leads to smaller effective population size
Term
 accuracy of selection vs. effective population size
Definition
 greater accuracy of selection reduces effective population size due to relatives being selected
Term
 Most selection schemes aim at...
Definition
 optimizing the factors that affect rate of genetic gain
Term
 The objective in optimized breeding strategies needs to be...
Definition
 maximizing genetic gain while restricting inbreeding
Term
 The factors that affect annual response to selection
Definition
 -genetic variance-accuracy of selection-intensity of selection-generation interval-population size
Term
 what increasing selection intensity does for inbreeding
Definition
 leads to rapid genetic gains, but also increases inbreeding
Term
 disadvantage of selecting young animals
Definition
 they have less information available
Term
 To optimize long term selection, it is useful to...
Definition
 combine selection on BLUP EBV with some restriction on the average relatedness of the selected animals
Term
 BLUP
Definition
 Best Linear Unbiased Prediction of breeding value
Term
 Selection by definition implies...
Definition
 lack of opportunity for all members of the population to mate
Term
 Non-random mating leads to...
Definition
 disequilibrium (non-random association of alleles)
Term
 disequilibrium
Definition
 non-random association of alleles
Term
 effect of disequilibrium (non-random association of alleles)
Definition
 reduces the genetic variance
Term
 how to calculate theoretical maximum response (Rmax)
Definition
 Rmax = 2Neih2σp Ne = effective population size
Term
 some factors that affect long term selection limits
Definition
 -Disequilibrium-Inbreeding (genetic drift)-Natural Selection-Number of loci-Physiological constraints
Term
 some natural selection factors that can affect long term selection limits
Definition
 -Fertility-Selection differential-Favoring heterozygotes
Term
 selection limit can be broken by...
Definition
 -Relaxing selection followed by selection-Mutations to generate “new” additive genetic variation
Term
 how the poultry industry maintains its populations
Definition
 -Primary breeders maintain large populations in replicates-Primary breeders limit the level of inbreeding per generation-Geneticists practice multi-trait selection with different weights on different traits.-Industrial lines can also benefit for mutations
Term
 advantage of multi-trait selection
Definition
 it does not exhaust genetic variance as much as selecting on a single traitThis can potentially ensure existence of genetic variation for many generations to come.
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