ITABILITY TABILITY PROBLEM Assume (for the Consider the following information on

Question

ITABILITY TABILITY PROBLEM Assume (for the Consider the following information on weaning weights from a large hend of zebras. moment) that there is no variation due to contemporary group effects. Herd average Breeding value variance Gene combination value variance Permanent environmental variance 300 Ib 900 82 121 375 Al. Calculate the heritability A2 One zebra foal (foal A) weighs 275 lbs at weaning and another foal (foal B) weighs 375 lbs What would the estimated breeding value (EBV) for weaning weight be for these two individuals? A3. Calculate the repeatability of a single recond. A4 Weaning weight of foals can also be used as a measure of the mother's maternal performance: that is foal weight is of ten thought of as a trait of the mare indicating her mothering ability. Calculate the most probable producing ability (MPPA), our estimate of producing ability, for mare A that produced one foal that weighed 400 lb and for another mare B that produced five foals with weights of 250, 300, 425, 370 and 436 lbs. (Hint: see pages 178 and 179 of your text book) A5 Our original assumption was that there was no environmental variation due to contemporary group effects. Now assume that there is contemporary group effect variation. How would you anticipate this would affect the MPPAs and EBVs you calculated, and briefly why? (No calculations needed here) PROBLEM B In wombats tameness is quantified by doing several tests and then calculating a temperament score for each individual. Higher numbers indicate more tame individuals. Your selected population of wombats has a particularly high value for tameness score because you have selected them to improve this characteristic for several generations. The mean tameness score for the whole population of wombats in the US. is 7.86 the mean tameness score for your selected population is 8.95. The variance for tameness is 2.1025 B1. What is the selection differential for this situation? B2. What is the selection intensity?

Explanation / Answer

Answer: In the field of ecology the general understanding to estimate the values in the extent of phenotypic variance or the environmental condition can be calculated based on the genetic data sets or the set of characters in the community of species.

A1: Heritability calculation- By definition heritability is the ratio of the genetic variance over the phenotypic variance.

Phenotypic variance for this population is

P = G (genetic variance) + E (environmental variance)

Vp = Vg + VE

Vp = 82 lb2 + (121 + 375 /2) lb2

Vp = 82 + 248 = 330 lb2

Heritability (H/h2) [resemblance between relatives] = Vg / Vp

h2 = Vg / Vp

= 82 lb2 / 330 lb2

= 0.248.

A2: Estimated breeding value (EBV) are the industry-tested measurement which is science based and of heritable traits that can be tracked and measured.

EBV = Phenotype – Environment

= 330 lb2 – 248 lb2 = 82 lb2.

A3: This repeatability is known as the correlation between subsequent records: the higher the repeatability shows that more they are alike.

We can calculate the parent-offspring regression and then we can use the value determining the repeatability.

B op = Va / Vp = h2.

b mass selection = nh2 / 1 +r (n-1)

n = number of repeated records, r = repeatability, h2 = regression coefficient,

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