Question

Fitness is the relative reproductive success of a genotype. We calculated the fitness values (W) for a series of genotypes to be as follows:

A¹A¹:   W₁₁ = 0.67
A¹A²:   W₁₂ = 1.00
A²A²:   W₂₂ = 0.45

After comparing these fitness values, you conclude that:

		It appears that one allele is favoured over another, therefore, directional selection is likely the form of selections.
		The fitness of the heterozygote is greater than both the homozygotes, and therefore overdominance is the likely the form of selection.
		The fitness of the heterozygote is greater than both the homozygotes, and therefore underdominance is the likely the form of selection.
		The fitness of the heterozygote is less than both the homozygotes, and therefore underdominance is likely the form of selection.
		The fitness of the heterozygote is less than both the homozygotes, and therefore overdominance is likely the form of selection.

Answer 1

ANSWER :-

1. The fitness values stated above are associated with genotypes and not particularly alleles and hence option 'A' cannot be considered as the most appropriate answer.
2. Option 'D' and option 'E' are also incorrect taking into consideration that the heterozygote is having less fitness value as compared to the homozygous dominant and recessive genotypes which does not seem to reflect from the data provided above. It can be seen that the fitness of heterozygote is '1' as compared to '0.67' for homozygous dominant and '0.45' for homozygous recessive individuals.
3. The fitness value of the heterozygotes is the highest as compared to the other homozygous genotypes although this can be stated as hybrid vigour or heterozygosity which favors overdominance and not underdominance and this indicates that option 'C' is not the most appropriate answer and option 'B' is the most appropriate answer.

So, option 'B' is the most appropriate answer