Question

1. How do chromosomal inversions affect genetic variation?

2. How do you calculate the change in mean fitness of a population due to natural selection on genotypes with different relative fitnesses?

3. Why is a sexually-reproducing organism a vehicle and not a replicator?

4. How does epistasis produce non-additive interactions among alleles?

Answer 1

1. When a chromosome undergoes breakage and rearrangement, inversion occurs. The change in chromosome occurs or the segment of chromosome is reversed end-to-end. This leads to the production of different proteins than required. Hence it leads to abnormal or deviation from normal or genetic variation.

2. Relative Fitness (w) is the survival and/or reproductive rate of a genotype relative to the maximum survival and/or reproductive rate of other genotypes in the population.  Calculate the Relative Fitness of each genotype by dividing each genotype's survival and/or reproductive rate by the highest survival and/or reproductive rate among the given number of genotypes.

Multiply the frequency of each genotype by the fitness of that genotype, then add up and find the mean. This is the mean fitness of one genotype. If ther is mean fitness one genotype known, and the relative fitness of the same genotype compared to another genotype known, then change in mean fitness can be calculated by subtracting mean fitness from relative fitness.

3. A sexually reproducing organism reproduce sexually price specialized cells celled gametes that are the vehicles that transmit genes. Each organism is unique in its germline but not a replicator. Hence, the organism carries a unique germline through generations.

4. Epistasis is the behavioural effect of interaction of gene alleles at multiple locus. The genes at different loci interact in non-additive way, to produce a particular trait. example, the genes for the human hair color and baldness can mask each other's effect and can produce or combine to produce an entirely new trait. Epistasis can occur in a variety of different ways and result in a variety of different phenotypic ratios. Thus the progeny produced will be in a ratio deviated from Mendel's independent assortment law which is 9:3:3:1.