Question

Can anyone help me with these questions please? Thanks.

1. How do the allele frequencies compare across generations? Do they change much or do they remain fairly constant? Briefly explain why this might be, and also briefly explain how different the pattern would be if the population were much larger.

2. In generation 3, strong assortative mating was imposed. Using data for the whole class, evaluate the hypothesis that generation 3 was in HWE using statistical analysis. Discuss the effects of assortative mating on genotype frequencies. Are homozygotes or heterozygotes more common?

3. The Soay sheep of St. Kilda Island near Scotland have changed coat color over the past 20 years, with dark colored sheep declining in frequency and light colored sheep increasing. Coat color is determined by the TYRP1 gene. The TYRP1­‐T homozygote is light colored, while TYRP1­‐G homozygotes and heterozygotes are dark. Discuss the hypothesis that assortative mating between sheep with similar coat color is the cause of the increase in light coat color over this period.

Answer 1

1) Allelic populatiions in ideal populations like those who would follow HWE will show no variation in allelic frequencies across generations. The allelic frequencies are compared using P+ Q = 1 formula for Allelic frequency finding , and p^2 + 2pq+ q^2 =1 Equations to find out allelic frequency from genotypic ones..

In real life populations the allelic frequencies do change across generations and can be seen to be changing for some Loci of genes or may be not changing for others , this all depends on what gene is under evolutionary forces like natural selection.

If the population were larger the effect would be lesser. So, more the population size more is the stability seen in allelic frequency.

2)Since data is not provided here, I can only tell you how to do the stuff.

You can see the data and analyse it using HWE which are written in 1st part as well. If the condition is met the population is in equilibrium.Under adsorptive mating however, the equilibrium might get disturbed. Because , it involved bon random mating and sexual selection, for like phenotype mates. Thus, the homozygosity is tend to increase in such populations of any of the 2 alleles or both. And heterozygosity decrease.

3) Here, dark colour coat trait is dominant. Therefore , initially it is evident that might be the recessive white colour coat was in lesser no. And frequency.

After adsorptive mating started the white coloured sheep started mating with there like phenotype sheeps only, thus producing more no. Of homozygous white sheep's. This is quite different from earlier time , when a homozygous white sheep had a equal chance of mating with a heterozygote or homozygous black or homozygous white one. Now , only homozygous white colour coat mating is prefered.

Thus, allelic frequency of white recessive gene would increase in population.

HIT THUMBSUP IF I COULD HELP.