In: Biology
In a population of mealybugs the dominant allele (G) frequency for an allele controlling fluffiness is 0.75. Selection is acting upon this locus such that the fitness values are gg=0.4, Gg=1, and GG=0.027. Simulate selection in the population by calculating gentoype frequencies following selection, and calculating allele frequencies from those genotype frequencies.
a. State which genotype is being favored by selection.
b. Give the normalized/corrected genotype frequency for gg following selection. Round your answer to the nearest thousandth (e.g., 0.123)
c. Give the allele frequency for G following selection. Round your answer to the nearest thousandth (e.g., 0.123)
a) Gg genotype is favored by selection as it has highest fitness (1) compared to other genotypes.
b) Given, frequency of G = 0.75, fitness of gg = 0.4, Gg = 1 & GG = 0.027
So, frequency of g = 1 - frequency of G = 1 - 0.75 = 0.25
So, frequency of GG = (frequency of G)2 = (0.75)2 = 0.5625
So, frequency of Gg = 2 x frequency of G x frequency of g = 2 x 0.75 x 0.25 = 0.375
So, frequency of gg = (frequency of g)2 = (0.25)2 = 0.0625
Now, mean fitness = (Frequency of GG x Fitness of GG) + (Frequency of Gg x Fitness of Gg) + (Frequency of gg x Fitness of gg) = (0.5625 x 0.027) + (0.375 x 1) + (0.0625 x 0.4) = 0.0152 + 0.375 + 0.025 (Up to 4 decimals) = 0.4152
So, after selection frequency of gg = (Frequency of gg x Fitness of gg) / mean fitness = 0.025 / 0.4152 = 0.0602 (Up to 4 decimals) = 0.060 (Up to 3 decimals)
c) Now, after selection frequency of GG = (Frequency of GG x Fitness of GG) / mean fitness = 0.0152 / 0.4152 = 0.0366 (Up to 4 decimals)
Now, after selection frequency of Gg = (Frequency of Gg x Fitness of Gg) / mean fitness = 0.375 / 0.4152 = 0.9032 (Up to 4 decimals)
So, frequency of G after selection = 1/2 of frequency of Gg + Frequency of GG = 1/2 x 0.9032 + 0.0366 = 0.4882 0.488 (Up to 3 decimals)