Question

heterozygote disadvantage Natural selection is the process by which organisms with the best adapted phenotype are selected for by environmental conditions. anthropogenic events such as the use of DDT heterozygote advantage Allelic frequencies can change due to selection or they may change due to genetic drift. environmental conditions The process of natural selection relies on the presence of of a gene within a population. genetic drift Deleterious alleles may persist in the population particularly if they confer a single allele The selection of two or more phenotypes is known as multiple alleles disruptive selection

Answer 1

1) Process of natural selection relies on the presence of multiple alleles of a gene in a population. When such situation occurs it can take forms of stabilising selection,directional selection or disruptive selection.

2) Deleterious alleles may persist in the population if they confer heterozygote advantage. This is a condition where the heterozygote genotype is favoured and has higher chances of survival than the the homozygous dominant or recessive types.IN that situation a bad allele might be preferred naturally by the population.

3) The selection of 2 or more phenotypes is known as disruptive selection. It is a type of natural selection that diversifies the population to have more than 2 types of phenotypes each of which are beneficial.to the population.

4) If an allele confers advantageous phenotype it may be lost due to random fluctuations.When genetic drift occurs the frequency of the alleles can increase or decrease and can cause a loss of some alleles. This occurs by pure chance or any natural disasters.

5) IN the long run random fluctuations result in alleles being lost or fixed. Over a period of time, due to random fluctuations whether the alleles are beneficial or not they are lost or fixed purely depending on chance.It can cause a good allele to be lost or a bad allele to be fixed. Fixation occurs after many generations of retaining a particular allele in the population.

6) Non random mating can mean that population will not exhibit hardy weinberg equilibrium because the law states that the variations in a population will be constant if the popualtion is random mating and there are no external factors to disrupt it. When non random mating occurs the genotype frequencies are altered and the equilibrium is lost.

7) New genetic variations can occur because of new mutations,gene duplications,exon shuffling,random genetic drift and darwinian selection. mutations can cause a deletion or addition or inversion of the genes of the allele and can lead to the formation of a new type of character favourable or bad to the environment. Gene duplication is a type of mutation itself that can cause any type of effect on the character.exon shuffling is a mismatch pairing of the exons in a gene that causes the polypeptide coded in the wrong way and makes the protein non functional and rarely useful.Genetic drift is a form of change in the allele frequencies in a population due to disruption in the normal equilibrium.Natural selection can also cause variations under different selective pressures.This type of variation is usually favourable for the organism.