Question

demonstrate how the opperation of evolutionary processes can be detected

Answer 1

Two processes result in the evolution of the organisms. The two evolutionary processes are given below:

• Genetic variability generated by the mutations that constantly arise in the population.
• Changes in the frequency of alleles within populations over time.

Natural selection partly determines the fate of the mutations that affect the fitness of their carrier. The ancestral allele present in the population is replaced when new alleles that provide higher fitness increases in frequency with time until they outreach fixation. This type of evolutionary process is called directional or positive selection. On the other hand, new mutations disappear from the populations if they decrease the carrier's fitness. This type of evolutionary process is called purifying or negative selection. The alleles that undergo a mutation which is advantageous only in heterozygotes not in homozygotes need to be maintained at an intermediate frequency in populations by the process called balancing selection.

Natural selection is not the only determinant that can direct diversity in the allele frequency. In every generation, allelic frequencies can also be changed solely as an outcome of the casual means of gamete sampling. This process is known as genetic drift.

The differentiation between natural selection and genetic drift is that diversity in allele frequency generated by genetic drift is not directional but just random. Eventually, genetic drift drives to the fixation of some alleles and the loss of other alleles.