Introduction to Population Genetics: The Hardy-Weinberg Principle

 

State the Hardy-Weinberg principle

            In the absence of:

                                    Selection

                                    Mutation

                                    Migration

                                    Genetic Drift (random chance)

                                    Non-random Mating

            Genotype frequencies can be predicted from allele frequencies AND

            Allele frequencies in a population will not change from one generation to the next

 

 

Describe how allele and genotype frequencies are calculated in a population.

Be able to calculate allele frequency from genotype frequency

(1/2H + R)/N = frequency of recessive allele = “q”

           

            Be able to calculate genotype frequency from allele frequency

            D = p2, H = 2pq, R = q2

 

Explain why the Hardy-Weinberg principle is useful in evolutionary biology

            identifies the forces that will cause evolution in the real world.  It is the null model.  If a population is not in HW equilibrium, one of the assumptions is being violated – further research may be productive

 

Be able to determine if Hardy-Weinberg assumptions hold by using Chi square analysis (of current population)

1.      Calculate allele frequencies         

2.      Calculate expected genotype frequencies

3.      Calculate expected number of genotypes

4.      Calculate chi-square test statistic

5.      Compare test statistic to table of critical values to determine if difference between observed and expected is significant

           

Probability (P value)

Degrees of Freedom

0.05

0.01

1

3.84

6.64