Question

Dobzhansky & Pavlovsky observed in a population box with an American Drosophila species, Drosophila pseudoobscura, that an inversion polymorph for the two naturally appearing inversion types Arrowhead (AR) and Chriricahua (CH) (which we assume to be codominant alleles in a autosomal locus) have the following relative fitnesses (egg to adultancy survival) of the three karyotypes (genotypes): AR/AR AR/CH CH/CH 0,75 1,000 ,42 One of the studies started with a population of adult flies, where probabilities of the AR inversion was 0.2 and for the CH inversion 0.8. Assume that the probabilities are the same for both sexes. a. What are the expected frequencies of AR and CH inversion among the next generation of adults, if we assume random mating? b. What will be the expected frequencies of the inversions AR and CH at equilibrium after many generations of mating? c. If we assume that the selection will only continue in the larval stage, and that there is random mating, what will be the expected frequency of the heterozygotes (AR/CH) and homozygotes (AR/AR & CH/CH) among adults and among eggs at equilibrium?

Answer 1

Expected frequency of inversion after many generale at quilibyium is - allele frequency, AR 20.50 CH= 0.50 : genotype frequency AR/ARO 0.25 ARSCH = 0.50 CH/CH? 8.25 ( 0 Expected frequency of ... ARICH" - {ex.(0.9) X(0.5) } 40.16*2? * 1 10:32 | AR/AR = {(0.23² x 0,75} ... CHICH = $10:8)? x 0.42% = 0.2688 or 10, 24(alborg Fitness - AR/ARZO 75 ARICHO 4 Cilet = 0.42. altele frequency, AR 002 CH20.8. genetybe frequently ARBAR2 0.04 ARICHS 0.22 ; CHfCH 20.64 Next generation allele frequency (fitness present) AR: (6.04x0.75) of (0.16*1). => 0.03 + 0116 -10.191 CH = (0.64X0:42) + (0.16.81) +0.268% +0 016 =0.4288 01431 ahborop.