Question

Describe the five assumptions of the Hardy-Weinberg model AND provide an example of how a population might violate each of the assumptions. (please type answer for easier read)

Answer 1

1) There must be no mutations occuring in the population.

2) There must be no natural selection taking place in the population

3) Individuals must mate at random

4) There is no genetic drift occuring in the population

5) There is no gene flow occuring within the population .  

All these assumptions assure that the allele and genotype frequency remains constant .

Examples :-

No Mutations :- If a mutation occurs ina population , it could give rise to a new allele . Depending on how beneficial or detrimental this allele is , it's frequency could decrease or increase . An increase in the frequency of a new allele means a decrease in the frequency of the other existing alleles . In addition , it also results in a change in the frequency of genotype as the mutant genotype frequency will increase and the other will decrease .

No Natural selection :- if there is natural selection occuring in the population , the allele and the genotype frequency will change according to what is favorable for that particular selection event . For allele and genotype that are favorable , the frequency will increase . For allele and genotypes that are unfavorable , the frequency will decrease .

Random mating :- This ensures that all of the alleles have an equal chance of being passed on to the next generation . When non mating occurs , there are two possible outcomes . The first is negative assortative mating in which the individuals that are phenotypically dissimilar to one another mate . This increases the genetic diversity and maintains both of the alleles at equal proportions in the population . The next is positive assortative mating in which individuals that are phenotypically similar mate with one another . This causes an increase the number of homozygotes and a decrease in the number of heterozygotes. The allele frequencies however , remain the same .

No genetic drift :- Genetic drift is the random change in allele and genotype frequencies , especially common with smaller population. When a population experiences genetic drift , the change in allele or genotypic frequency is random and cannot be predicted . Eventually however , one of the allele for the trait will reach fixation (100% ) and the other will be lost (0%)

No Gene flow :- Gene flow occurs when individuals migrate from another population and bring their genetic information into the gene pool of the population that they are migrating too . This causes a change in the allele as new allele that were once at 0% in the population will began to increase through mating . In addition , alleles that already exist in the population will bring to decline , being less frequent than the last generation , but not totally lost .