Write a short notes on Neo-Darwinism.

Neo-Darwinism was proposed by Fischer, Sewall Wright, Mayr. According to this theory five basic factors are involved in the process of organic evolution.

• Gene mutations: Changes in structures of a gene are called gene mutations. They produce variations.
• Chromosomal mutations: Changes in the structure of chromosomes. They also bring varitations in phenotype.
• Genetic recombination: They are due to crossing over during meiosis.They also bring heritable variations.
• Natural Selection: It is a driving force of evolution. Beneficial variations are selected by nature.
• Reproductive isolation: It is the absence of gene exchange between populations. It results in speciation.