# Handout17 - Heritability(h 2 • broad sense h 2 B = s 2 G 0< h 2 B< 1 s 2 P • narrow sense h 2 = s 2 BV 0< h 2< h 2 B< 1 s 2 P Genetic

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1 Lecture 17 Regression and Heritability Covariance Statistics Correlation Regression -- the change in one variable per unit change in another variable Regression 1 unit ? m x m y

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2 Regression b y on x = s x,y s x 2 b x on y = s x,y s y 2 b y on x =the slope of the line in the graph on previous slide. Example: Beef weaning weight = 7 months m ww = 600 yearling weight = 12 months m yw = 1100 s 2 ww = 1600 s 2 yw = 14400 s ww, yw = 4000 r ww, yw = 4000 = .833 1600 14400 b yw on ww = 4000/1600 = 2.5 Regression Prediction Equation y = m y + b y on x (x - m x ) Individual = 650 lbs yw = 1100 + 2.5 (650 - 600) = 1225 ˆ ˆ
3 Genetic Parameters Start with s 2 P , why do records vary? P 1 = m + G 1 + E 1 G 1 G 2 P 2 = m + G 2 + E 2 E 1 E 2 Genetic Parameters s 2 P = s 2 G + s 2 E s 2 G = variance due to genotypes s 2 E = variance due to environment Genetic Parameters Consider: s 2 G G = BV + DOM + EPI s 2 G = s 2 BV + s 2 DOM + s s 2 EPI s 2 BV = s 2 A (breeding value variance or additive genetic variance)

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Unformatted text preview: Heritability (h 2 ) • broad sense h 2 B = s 2 G 0 < h 2 B < 1 s 2 P • narrow sense h 2 = s 2 BV 0 < h 2 < h 2 B < 1 s 2 P Genetic Control versus Heritability • s 2 G and s 2 BV exist if there is polymorphism at the loci involved in controlling the trait that impacts performance. • When h 2 = 0 & no difference among breeding values but still could be substantial genetic control. Types of Traits • One measurement taken -- birth weight • Multiple measurements taken --litter size, milk yield 5 Genetic Parameters Consider: s 2 E E -- permanent and temporary environment E= PE + TE PE -- influences all records on an individual TE -- influences a single record, different TE for each record s 2 E = s 2 PE + s 2 TE...
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## This test prep was uploaded on 03/31/2008 for the course AN SC 221 taught by Professor Pollak,ej during the Spring '07 term at Cornell University (Engineering School).

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Handout17 - Heritability(h 2 • broad sense h 2 B = s 2 G 0< h 2 B< 1 s 2 P • narrow sense h 2 = s 2 BV 0< h 2< h 2 B< 1 s 2 P Genetic

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