Evolution is the sequence of gradual changes over millions of years in which new species are produced. Charles Robert Darwin was an English naturalist proposed theory of Natural Selection. Variations are the differences in characters among individuals of a species. Mutation is a sudden, random, unwanted and heritable change in the organisms . Gene Flow is transfer of genes from one population to another population. Movement of living organisms from one place to another place for protection, reproduction, shelter is known as Migration. Natural selection explains that the organisms which are physiologically, behaviourally better adapted for environment are selected. They can survive and reproduce.
Genetic Drift is a deviation from a small population due to chance variation.Species can be defined as a group of individuals of same kind which can interbreed and produce fertile progeny. Any reproductive isolation leads to Speciation, which mean formation of new species from a single species. Process of speciation - genetic drift: It is due to changes in the frequencies of particular genes by chance alone. Process of speciation - Natural selection: Variations caused in individuals due to natural selection leads to formation of new species. Process of speciation - splitting of population: A population splits into different sub populations due to geographical isolation that leads to formation of new species.