Question

1) The following number of allozyme (protein) genotypes at a shell deposition locus of the barnacle (Semibalanus balanoides) were identified in a sample of 1000 barnacles from coastal Rhode Island before a hurricane: 90RR, 420RS and 490SS individuals. (R stands for rapid migrating allele; S stands for slow moving allele in gel electrophoresis)

a) What are the allele frequencies for this population?

b) Are the barnacles in Hardy-Weinberg equilibrium for this allozyme?

After the hurricane the barnacle population was resampled with the following results: 90RR, 378RS and 392SS.

c) What is the relative fitness of the genotypes?

d) What are the selection coefficients?

e) What are the new allele frequencies after selection?

This is all the information given.

Answer 1

Answers: for calculating relative Fitness, we need to know the Chance of survival Here is the case, chance of Survival is colculated by dividing the number of individuals in each quotipe. Survived after hurricane with the total number of individuals in each quotype before Hurricame. Respectively Chance of survival for different genotypes, RR = 90/90 =1 or 100% Rs = 378/420= 0.9lor 90% and SS = 392/490 = 0.8 or 809. Now, relative Fitness (co) con be colculated for each quotype by dividing the chance of Survival of each quotype with the Highest chance of survival of the quotypes under comparision. WRR = 100/100 = 1; Was = 90/100=0.9, and css = 80/100 = 0.8 the selection co-effecient (s) is colculated of 1-W. SRR = 1- WRR = 1-1=0, Spr=1- Wps = 1-0.9 = 0.1 and Sss = 1- Was = 1-0.8 = 0.2

ter selection, the total number of qune copies in the whole population (Rts) = 90 +378 + 392 = 860. There are only two Alleles Ronds, and their Allele Frequencies Ariomoted by the symbols pond a P= frequency & R = 90+ 189/860=279/860=0.32 q= lequely ds = 189+ 392 / 860 = 581/860 = 0.68 Note: Frequency o R = RR + Rs = 90 + 378/2 = 90+189 ond Irequely ds = Rs+ ss = 378/2+ 392 = 189+ 392. Since, an individual will have only one Allele, individuals with Rs quotype com give either R Allele ovs Allele]