Genetic variation is the differences in genetic material between individuals of the same species. It is caused by mutations, which are changes in the DNA sequence of an organism. Mutations can be caused by environmental factors or random errors during DNA replication. The term 'MUTANT' is used to describe an organism that has a mutation in its genetic code. MUTANT organisms often have different physical characteristics from their non-MUTANT counterparts. Genetic variation is important for evolution, as it allows species to adapt to changing environments and increases the chances of survival.