Term

Definition
Traits or Characters that are affected by one or few genes, and follow a discontinuous variation. 


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Definition
discontinuous traits quantitative traits 


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distribution of genotypes is affected by... 

Definition
the number of genes involved 


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what happens as the number of genes affecting a trait increases? 

Definition
the transition between each genotypic class becomes less distinct, such that it resembles a bell curve, known as normal distriibution 


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Definition
Traits that are affected by many genes, and exhibit continuous variation 


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some examples of quantitative traits 

Definition
growth egg weight breast meat yield 


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Quantitative traits are... 

Definition


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Definition
traits affected by many genes 


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other than each other, what do alleles interact with to produce traits? 

Definition


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The analysis of a quantitative trait starts by... 

Definition
describing the phenotype of a given trait in a population 


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the distribution most quantitative traits follow 

Definition


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the statistical parameters that govern normal distribution 

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standard normal distribution 

Definition
A normal distribution with a mean of zero and a variance of 1 


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amount of population within 1 standard deviation of the mean in a standard normal distribution (μ – 1σ and μ + 1σ) 

Definition


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amount of population within 2 standard deviation of the mean in a standard normal distribution (μ – 2σ and μ + 2σ) 

Definition


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amount of population within 3 standard deviation of the mean in a standard normal distribution (μ – 3σ and μ + 3σ) 

Definition


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how to calculate proportions of a normal distribution 

Definition
Z = (X_{i}  μ) / σ
then find probability of it on the Z score table 


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symbols for mean, variance, and standard deviation for population and sample 

Definition


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Definition


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Definition


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Definition


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Definition


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Definition
population standard deviation 


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Definition
sample standard deviation 


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Definition


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Definition
Mean = x̄ = (ΣX) / n
x̄ = mean phenotypic value of the sample
X_{i} = the i^{th} phenotypic value
Σ = the summation sign 


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Definition
in the breeding context, this refers to differences among individuals in a population 


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Variation is the source of... 

Definition


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the raw material for geneticists 

Definition


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The most commonly used measures for variation 

Definition
variance standard deviation 


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Variation is measured by... 

Definition
variance or standard deviation 


Term
how to calculate variance 

Definition
σ^{2} = Σ(X_{i}  μ)^{2} / N
N = number of individuals in that population 


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the best estimate of population variance 

Definition


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how to calculate sample variance 

Definition
S^{2} = Σ(X_{i}  x̄)^{2} / (n  1)
or
S^{2} = (ΣX_{i}^{2}  ((ΣX_{i})^{2} / n)) / (n  1) 


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how to calculate standard deviation 

Definition


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Definition
Y increases as X increases 


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Definition
Y decreases as X increases 


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Definition
Y stays the same as X increases or decreases 


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3 basic concepts of covariation 

Definition
1.The direction or sign of the relationship, i.e. whether the relationship is positive, negative or nonexistence. 2.The strength of the relationship. 3.The amount of change in one variable that can be expected for a given amount of change in another variable. 


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Definition
1. Covariance 2. Correlation 3. Regression 


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Definition
the average product of deviation from the means of two variables 


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how to calculate covariance 

Definition
Cov(X,Y) = (Σ(X_{i}Y_{i}  n *X̄*Ȳ)) / (n1) 


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Definition
a measure of the degree of the relationship between two variables; indicates relationship and strength of it 


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how to calculate linear corelation 

Definition
r_{xy} = (Cov(x,y)) / (s_{x} * s_{y})
r_{xy} = r_{yx} 


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The simplest functional relationship of one variable to another 

Definition
the simple linear regression 


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Definition
the quantitative change in one variable that can be expected for a unit change in another variable 


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the variables involved in linear correlation 

Definition
dependent variable independent variable 


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relationship between dependent and independent variable 

Definition
the magnitude of the dependent variable is determined by the magnitude of the independent variable 


Term
the relationship between dependent and independent variables if they're linearly related 

Definition
Y = a + b_{yx}X
this is Y on X, i.e. b_{yx} ≠ b_{xy}
Y = the dependent variable
X = the independent variable
b = regression coefficient
a = point of intersection (the value of Y when X =0) 


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linear regression on a graph 

Definition


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how to calculate regression variable 

Definition
b_{yx} = (Cov(X,Y)) / (Var(X))
b_{xy} = (Cov(X,Y)) / (Var(Y))
b_{yx} ≠ b_{xy} 

