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State hardy-Weinberg principle of genetic equilibrium.Knowing that genetic drift disturbs this equilibrium mention what does this disturbance is genetic equilibrium lead to?
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Solution :
Hardy Weinberg’s principle states that allele frequencies in a population are stable and is constant from generation to generation.
Five factors known to affect Hardy Weinberg equilibrium are:
a. Genetic migration/Gene flow
b. Genetic drift
c. Mutation
d. Genetic recombination
e. Natural selection.
a. Genetic migration: When migrations of a selection of population to another place occur, gene frequencies change in the original as well as the new population. New genes/alleles are added to the new population and these are lost from the population.
b. Genetic drift/Sewal Wright effect: This theory was proposed by Sewall Wright in 1930. It deals with the gene frequency of a reproducing small population. In a small population not all the alleles, representatives of that species may be present.
Thus the inheritance process is in violation of Hardy-Weinberg law.
In a small population, a chance event may increase the frequency of a character that has little adaptive value. Thus genetic drift may be a significant factor in the origin of new species on islands and other isolated populations. Continuous mating within such populations decreases the proportion of heterozygotes and increase the number of homozygotes. However, the small population as a whole may develop characters different from that found in the main population. Such deviations may lead to speciation or formation of new species.
When a small group of individuals due to genetic drift becomes the founders of a new population, the phenomenon is termed as “founder’s principle”. The new population often has genotype frequencies different from parent population. Sometimes genotypic frequencies may get changed in a small population isolated temporarily due to natural calamities.
When the population regains its original size, the members of the small population may have diverged genetically from the original parental population. Hence interbreeding between members of small and larger population may not be possible. The small population might have evolved into a new species. This type of genetic drift is known as “bottle neck effect”.
c. Mutations: Mutations are considered as raw materials for evolution. They help to create and provide variations in a population along with genetic recombinations. The collection of genes in a population is referred to as “gene pool”. Mutations enrich the gene pool with new modified genes. A large scale accumulation of such genes will lead to evolutionary modifications.
d. Genetic recombinations: During meiosis, due to crossing over of chromosomes, genetic arrangements get altered. Such alterations cause reshuffling of gene combinations. Such recombinations are regular events in gametogenesis. Due to such events, new allelic formations happen and after fertilization, variations result in progeny.
e. Natural Selection: In the modern or synthetic theory of evolution, natural selection is considered as a population related genetic phenomenon. It leads to change in allele frequencies and favours or promotes adaptation as a product of evolution
When the population size of animals or plants in a specific locality increases, certain environmental factors such as availability of food may become limiting factors. Those organisms exhibiting characteristics which give them a competitive advantage may survive. Thus population size and environmental limiting factors operate together to produce selective pressure.
The selective pressure may increase or decrease the spreading of an allele in a gene pool depending on its adaptive value which in turn will lead to evolutionary changes.
Important Attributes of a genetic Code are as follows
The genetic code is triplet.
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Solution :
Hardy Weinberg’s principle states that allele frequencies in a population are stable and is constant from generation to generation.
Five factors known to affect Hardy Weinberg equilibrium are:
a. Genetic migration/Gene flow
b. Genetic drift
c. Mutation
d. Genetic recombination
e. Natural selection.
a. Genetic migration: When migrations of a selection of population to another place occur, gene frequencies change in the original as well as the new population. New genes/alleles are added to the new population and these are lost from the population.
b. Genetic drift/Sewal Wright effect: This theory was proposed by Sewall Wright in 1930. It deals with the gene frequency of a reproducing small population. In a small population not all the alleles, representatives of that species may be present.
Thus the inheritance process is in violation of Hardy-Weinberg law.
In a small population, a chance event may increase the frequency of a character that has little adaptive value. Thus genetic drift may be a significant factor in the origin of new species on islands and other isolated populations. Continuous mating within such populations decreases the proportion of heterozygotes and increase the number of homozygotes. However, the small population as a whole may develop characters different from that found in the main population. Such deviations may lead to speciation or formation of new species.
When a small group of individuals due to genetic drift becomes the founders of a new population, the phenomenon is termed as “founder’s principle”. The new population often has genotype frequencies different from parent population. Sometimes genotypic frequencies may get changed in a small population isolated temporarily due to natural calamities.
When the population regains its original size, the members of the small population may have diverged genetically from the original parental population. Hence interbreeding between members of small and larger population may not be possible. The small population might have evolved into a new species. This type of genetic drift is known as “bottle neck effect”.
c. Mutations: Mutations are considered as raw materials for evolution. They help to create and provide variations in a population along with genetic recombinations. The collection of genes in a population is referred to as “gene pool”. Mutations enrich the gene pool with new modified genes. A large scale accumulation of such genes will lead to evolutionary modifications.
d. Genetic recombinations: During meiosis, due to crossing over of chromosomes, genetic arrangements get altered. Such alterations cause reshuffling of gene combinations. Such recombinations are regular events in gametogenesis. Due to such events, new allelic formations happen and after fertilization, variations result in progeny.
e. Natural Selection: In the modern or synthetic theory of evolution, natural selection is considered as a population related genetic phenomenon. It leads to change in allele frequencies and favours or promotes adaptation as a product of evolution
When the population size of animals or plants in a specific locality increases, certain environmental factors such as availability of food may become limiting factors. Those organisms exhibiting characteristics which give them a competitive advantage may survive. Thus population size and environmental limiting factors operate together to produce selective pressure.
The selective pressure may increase or decrease the spreading of an allele in a gene pool depending on its adaptive value which in turn will lead to evolutionary changes.
Important Attributes of a genetic Code are as follows
The genetic code is triplet.
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