Discuss the effects of population size on both the eventual

Discuss the effects of population size on both the eventual fate of an allele (fixation, loss) and time to fixation.

Solution

The phenotype of an individual is greatly influenced by its genotype and the environment. The evolution takes place basing on the natural selection of characteristics in an individual. The phenotypic variations are caused through the substantial genetic variations in the organisms. The genetic variation in an organism may result in high or low frequency of an allele and may reach the fixation at a particular time. The new allele may replace the ancestral allele completely and results in the genetic variation in the new generation.

The natural selection can be expressed in terms of inheritance of characteristics that genetically vary from one generation to other. But, evolution and inheritance of new characteristics may not be in equilibrium and hence, the new alleles may be lost rapidly. Establishment of equilibrium between selection and inheritance can be better explained by the Hardy – Weinberg equation which maintains the population with genetic variation at equilibrium or constant in absence of selection, mutation, migration and genetic drift. The variation at genetic level is obtained by mutations or sexual reproduction. Migration or gene flow may also result in variation. Thus, small differences at genetic level will lead to the formation of new species or evolution of the population.

A low gene pool with minimal variation can have minimum phenotypic variation. The changes in the environment in which the species live, would have less chances to get adapted and the survival rate may become low and producing fertile offspring may also become low. A large gene pool may have large variations and different phenotypes may have increased chances of adapting the changes in the environment and survive and produce fertile offspring. Hence, large gene pools have better advantages than the small gene pools with minimum variation. The small gene pools with minimum variation have dangers like extinction of species by loss of specific alleles.