Variation is a result that leads to a difference or deviation (for example, structure, form, function) from the recognised norm or standard. It is a modification in structure, form or function in an organism, deviating from other organisms of the same species or group. There are two types of variation: interspecific variation and intraspecific variation. Interspecific variation is when one species differs from another like mammals differ from fish. These differences are explained through differing ancestries explained by the difference of genetics perhaps due to natural selection. However, intraspecific variation is when members of the same species differ from each other like how there are many different types of cats. This can be mainly explained through mutations.
Variation is the result of two main factors: genetic differences and environmental influences. In most cases it is a combination of both factors. Additionally, in asexual reproduction, variety can only occur through mutations whereas off springs that have been produced sexually the variety will be more apparent due to the probabilities being higher due to more factors contributing to the cause of variation such as meiosis and fusion of gametes, as well as mutation.
Genetic differences are due to the different genes that each individual organism possesses. The differences occur arise in living organisms and change from generation to generation. Genetic variation arises as a result of mutations, meiosis and fusion of gametes. Mutations are changes in DNA that result in the offspring containing different characteristics by the changing of quantity or structure of the DNA. The end result of the process of altering the DNA structure is a different amino acid sequence that leads to a formation of a different polypeptide, and hence a different protein, or no protein being produced at all. So, as proteins are responsible for the characteristics of an organism, it follows that