The standard deviation is the square root of the variance: sx = VSx = V2Î6 = 14.70
To calculate the correlation coefficient and regression coefficient, we need the covariance:
(b) In a regression of the mean phenotype of the offspring against the mean phenotype of the parents, the regression coefficient equals the narrow-sense heritability, which is .80.
(c) We conclude that 80% of the variance in height among the members of these families results from additive genetic variance. 4. A farmer is raising rabbits. The average body weight in his population of rabbits is 3 kg. The farmer selects the 10 largest rabbits in his population, whose average body weight is 4 kg, and interbreeds them. If the heritability of body weight in the rabbit population is .7, what is the expected body weight among offspring of the selected rabbits?
The farmer has carried out a response-to-selection experiment, in which the response to selection will equal the selection differential times the narrow-sense heritability. The selection differential equals the difference in average weights of the selected rabbits and the entire population: 4 kg — 3 kg = 1 kg. The narrow-sense heritability is given as .7; so the expected response to selection is: R = h2 X S = .7 X 1 kb = 0.7 kg. This is the increase in weight that is expected in the offspring of the selected parents; so the average weight of the offspring is expected to be: 3 kg + 0.7 kg = 3.7 kg.
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