Question

• Discuss factors that lead to genetic variations in a population by using the Hardy-Weinberg law that describes allele frequencies in a population. • Explain how animal behaviors, including human behaviors, are governed by genetic inheritance. • Explain how the laboratory mouse has become a valuable model organism for the study of development and genetics. • What other animal models are used? • What contribution(s) has research using Caenorhabditis elegans and Drosophila melanogaster made in the study of animal behavior and population genetics? • Elaborate on the future of human disease diagnosis using the data from the Human Genome Project. • Provide sufficient examples to make the speech relevant to high school students.

Answer 1

In order to be in hardy Weinberg equilibrium a population must satisfy following 5 conditions:-

1. Random mating

2. No gene flow

3. Very large population size

4. No mutation

5. No natural selection

If any of these conditions are not fulfilled then the population does not remain in hardy Weinberg equilibrium , instead it start evolving and show genetic variation. Allele frequency may change from one generation to the next.

Violation of hardy Weinberg conditions lead to genetic variation:-

1. Non - random mating:- In non - random mating organism may prefer to mate with the individual of same genotype or other genotype. It won't make changes in the allele frequency but it can alter genotype frequency.

2. Gene flow:- gene flow involves movement of genes into or out of a population. Organism and gametes that enter a population may have new alleles or may bring in existing alleles in different proportions.

3. Small population size:- This is also referred as genetic drift. Genetic drift involve changes in allele frequency due to chance event usually " sampling error" . Drift can occur in population of any size but it has a stronger effect on small population.

4. Mutation:- although mutation is the actual source of genetic variation , the mutation rate for most organism is quite low. So the impact of new mutation on allele frequency from one generation to the next is usually not large.

5. Natural selection:- natural selection occurs when one or more allele makes an organism more or less fit, that is, able to survive and reproduce in a given environment.

These are the factors that lead to genetic variation in a population by changing allele frequency.