Question

explain why genetic variation is so important in natural populations, and how it arises and is maintained. explain hardy-weinberg equilibrium as it reltes to the genetic variations and maintenance in populations. include in the explanation: all the equations relating to allele frequencies and genotypic frequencies, and the 5 assumptions.

Answer 1

Genetic variation: Genetic variation is the changes in genes or allele with in the population which is the way of population to adapt and survive the changes occur in the environment It has important role in evolution which favor’s the natural selection by increasing the low frequency alleles occur in the population.

Sources of Genetic variation: Mutation and recombination, Gene flow and sexual reproduction are the three major source of genetic variation.

Mutation and recombination: is the alteration of DNA sequence, Recombination is the crossing over between the chromatids during meiosis.

Gene flow: Is the transfer of gene from one population to another population

Sexual reproduction: gene shuffling during sexual reproduction is another source of genetic variation.

Hardy – Weinberg Equillibrium: Hardy-Weinberg principle states that the genotype frequency and allele in a population will be constant from generation to generation absence of any disturbing factors. Hardy-Weinberg equilibrium is disturbed by various factors such as genetic drift, gene flow, non- random mating, natural selection and mutation.

Genetic drift: Sometimes random changes occur in the number of allele, these changes in the frequency of relative allele is temed as genetic drift. Usually genetic drift occur in a small population. The population size may reduce due to significant amount of individual die or prevent from breeding will result genetic drift.

Mating pattern: Non random mating is an another reason for changing the equilibrium, it occur either by inbreeding or out breeding. Inbreeding occur due to individual mating with similar genotype. Out breeding occur due to the mating of individual of particular genotype will mate with another particular genotype.

Natural selection: Is a key mechanism in evolution. The survival of organism with favorable trait and reproduction, which can pass their new trait to new generation and the new generation can survive at particular environment.

Gene Flow: Is the transfer of genetic changes from one population to another population.

Equation:    p + q =1

               p² + 2pq+ q² =1

A gene has to alleles A (dominant), a (recessive)

A is represented by p, a is represented by q

AA = p² , aa = q² , Aa = pq