Gunpreet, Subject Matter Expert at Edumarz
Answer: We know that reproduction is a process that gives rise to new individuals that are similar, yet different. Organisms inherit their characters from their parents along with subtle changes. When these organisms reproduce, the next generation will have differences that they inherit from the first generation, along with newly created differences. These differences accumulated over generations creates a new variant of a species. These differences are called variations.
The variations arise due to small inaccuracies in DNA copying and also due to some environmental factors. Variations arise in both asexual reproduction and sexual reproduction however, maximum variations arise in sexual reproduction. These variations help the species to adapt themselves in the changing environmental conditions and thus help them in their survival. For example: Heat tolerant varieties of bacteria can survive better in a heat wave than those variants which cannot tolerate heat. In this way, creation of variations in a species promotes survival and this forms the basis for evolutionary processes.