1 a In a sample of mushrooms from a forest floor three genot

1) a. In a sample of mushrooms from a forest floor, three genotypes comprised of two alleles (A and B) at one locus showed the following numbers in the population:

fAA = 15

fAB = 80

fBB = 5

Are these numbers what you would expect if this population was in Hardy-Weinberg equilibrium? Do not do a Chi Square analysis. Simply make a qualitative conclusion by comparing expected (if in HWE) and observed (given above) genotype frequencies. Show your work.

b. Define natural selection and fitness, using the word genotype frequency in your definition.

Solution

a. Genotypic frequencies are: fAA = 15/100 = 0.15;  fAB = 80/100 = 0.8;  fBB = 5/100 = 0.05

Then allelic frequencies: fA = (0.15)² + 1/2 x 0.8 = 0.0225 + 0.4 = 0.4225:

fB = (0.05)² + 1/2 x 0.8 = 0.0025 + 0.4 = 0.4025

According to Hardy wein berg rule: (A+B) ² = 1

(0.4225 + 0.4025) ² = 1

(0.825) ² = 1

0.648 NOT EQUAL TO 1

So the above data is not in HW equilibrium

b. Natural selection is the variability in survival and reproduction of individuals due to differences in genotype. It is a the important mechanism of evolution for change in heritable traits of a population over time.

Fitness is the abiliity of an organism to survive and transmit its genotype to reproductively fertile offspring as compared to competing organisms. It is also the contribution of an allele or genotype to the gene pool of subsequent generations as compared to that of other alleles or genotypes.