Neutralism

The neutral theory was one of the most controversial theories in biology in the late twentieth century. This chapter discusses skepticism of scientists regarding the theory of neutralism, evidence and arguments offered on behalf of the theory, how the test of the theory have been carried out, and what is a drift in context of the neutral theory. It also explains what are the implications of neutrality at the molecular level (if any) and describes adaptation. Neutralism claims that many phenotypic traits have no effect on an organism's fitness. The organism's phenotype consists of its physical and behavioral characters or traits-from height to color of plumage. However, Kimura's Neutralists claims that the amino acid and nucleotide changes that accumulate within the species in the course of evolution are mainly due to random fixation of selectively neutral mutants. He also gave a very elegant mathematical argument, demonstrating that if the neutral theory was true, the rate of change in the genetic constitution of a population should be exactly proportional to the mutation rate and independent of population size.