n a longitudinal study, 100 children born on the same day were sampled in a population of interest, and genotyped at one locus that has two alleles, A1 and A2. The children were followed every seven years until adulthood. At the end of the study, 75 reproductive adults remained from the original cohort of 100 children. Genotype A1A1 A1A2 A2A2 Number of Children 48 36 16 Number of Adults 30 27 18 a) If selection is acting on this locus, predict the genotype and allele frequencies of this locus when the population reaches equilibrium (no calculation necessary). b) If the adults in the sampled cohort represent the parents of the next generation of offspring in the population, and assuming random mating among the adults to produce the children of the next generation, calculate the predicted genotype frequencies in the children of the next generation.
Genetic Variation
Genetic variation refers to the variation in the genome sequences between individual organisms of a species. Individual differences or population differences can both be referred to as genetic variations. It is primarily caused by mutation, but other factors such as genetic drift and sexual reproduction also play a major role.
Quantitative Genetics
Quantitative genetics is the part of genetics that deals with the continuous trait, where the expression of various genes influences the phenotypes. Thus genes are expressed together to produce a trait with continuous variability. This is unlike the classical traits or qualitative traits, where each trait is controlled by the expression of a single or very few genes to produce a discontinuous variation.
In a longitudinal study, 100 children born on the same day were sampled in a population of interest, and genotyped at one locus that has two alleles, A1 and A2. The children were followed every seven years until adulthood. At the end of the study, 75 reproductive adults remained from the original cohort of 100 children.
|
Genotype |
A1A1 |
A1A2 |
A2A2 |
|
Number of Children |
48 |
36 |
16 |
|
Number of Adults |
30 |
27 |
18 |
a) If selection is acting on this locus, predict the genotype and allele frequencies of this locus when the population reaches equilibrium (no calculation necessary).
b) If the adults in the sampled cohort represent the parents of the next generation of offspring in the population, and assuming random mating among the adults to produce the children of the next generation, calculate the predicted genotype frequencies in the children of the next generation.
c) From the predicted genotype frequencies in (b), calculate the allele frequencies and the HWE expected genotype frequencies in the children of the next generation. Are these children in HWE?
d) Use the allele frequencies from (c) to calculate the mean fitness ϖ in the population in the next generation, given that ϖ = p2w11 + 2pqw12 + q2w22
e) Using the relative fitnesses w11 = 0.556, w12 = 0.667, w22= 1, calculate the change in genotype frequencies from childhood to adulthood in the next generation, and calculate the mean fitness ϖ in the population in the next generation.
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