The original population of 200 was hit by a flash flood and 100 organisms were wiped out, leaving 16 homozygous recessive out of the 100 survivors. If all individuals were equally likely to be wiped out, what was the effect of the flash flood on the population distribution/equilibrium? What is the frequency of homozygous recessive? What is the predicted frequency of heterozygotes? What is the predicted frequency of homozygous dominant?

frequency of homozygous recessive = q² = 0.16

the predicted frequency of heterozygotes = 2pq = 2 × 0.4 × 0.6 = 0.48

the predicted frequency of homozygous dominant = p² = 0.6² = 0.36

Explanation:

Given that:

Number of recessive homozygous survivors = 16

Total number of population survivors = 100

Predicted frequency of homozygous recessive individuals (q²) = 16/100 = 0.16

Frequency of recessive allele (q) = √0.16 = 0.4

p + q = 1

∴ p = 1 - q = 1 - 0.4 = 0.6

Frequency of dominant allele (p) = 0.6

frequency of homozygous recessive = q² = 0.16

the predicted frequency of heterozygotes = 2pq = 2 × 0.4 × 0.6 = 0.48

the predicted frequency of homozygous dominant = p² = 0.6² = 0.36

p² + q² + 2pq = 1

0.16 + 0.36 + 0.48 = 1 (proved)

The reduction in population due to some event in the original gene is no longer in the surviving population. Since the population is now small, there is likely to be genetic drift.

The flash flood caused change in allele frequency leading to a micro evolution.

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