Ozalla village has 1000 persons made up of 650 dominant homozygotes, 100 heterozygotes, and 250 recessive homozygotes. Is the population governed by Hardy-Weinberg law? List the conditions that must be kept constant for the Hardy-Weinberg principle to be operational in the village.
Answer (2)
The Ozalla village population likely does not follow the Hardy-Weinberg principle, as the observed and expected genotype frequencies do not match. For Hardy-Weinberg equilibrium, conditions such as large population size, no mutations, no gene flow, random mating, and no natural selection must be met. An analysis shows significant discrepancies between observed and expected values, indicating violations of these conditions.
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To determine whether the population in Ozalla village is governed by the Hardy-Weinberg principle, we need to check if the genotype frequencies are in equilibrium. According to the Hardy-Weinberg principle, a population is in genetic equilibrium if the allele and genotype frequencies remain constant from one generation to the next, provided that certain conditions are met.
Frequency Calculation
Let's denote:
p as the frequency of the dominant allele.
q as the frequency of the recessive allele.
From the problem:
Number of dominant homozygotes ( AA ) = 650
Number of heterozygotes ( A a ) = 100
Number of recessive homozygotes ( aa ) = 250
Total population = 1000
The genotype frequencies are:
f ( AA ) = 1000 650 = 0.65
f ( A a ) = 1000 100 = 0.1
f ( aa ) = 1000 250 = 0.25
The frequencies of the alleles can be determined by:
p = f ( A ) = f ( AA ) + 2 1 f ( A a ) = 0.65 + 2 1 ( 0.1 ) = 0.7
q = f ( a ) = f ( aa ) + 2 1 f ( A a ) = 0.25 + 2 1 ( 0.1 ) = 0.3
To be in Hardy-Weinberg equilibrium, the expected genotype frequencies will be:
p 2 = ( 0.7 ) 2 = 0.49
2 pq = 2 ( 0.7 ) ( 0.3 ) = 0.42
q 2 = ( 0.3 ) 2 = 0.09
Since the observed genotype frequencies ($0.65 , $0.1 , $0.25 ) do not match the expected Hardy-Weinberg frequencies ($0.49 , $0.42 , $0.09 ), the population is not in Hardy-Weinberg equilibrium.
Conditions for Hardy-Weinberg Equilibrium
To maintain Hardy-Weinberg equilibrium, the following conditions must be met:
Large Population Size : The population must be large enough to prevent random changes in allele frequencies.
No Mutation : There should be no mutation altering the alleles.
Random Mating : Individuals must pair by chance and not according to their genotypes.
No Gene Flow : There should be no movement of individuals into or out of the population which can alter allele frequencies.
No Selection : All individuals must have an equal chance of survival and reproduction, meaning no natural selection.
