variation

• Genetic variation — the set of genes inherited by the mother and the father.
• Environment variation — as organism grows and develops.
• Continuous variation — a trait that can be measured on a scale from low to high. eg: weight and height.
• Discontinuous variation — limited number of phenotypes with distinct groups. eg: blood groups.
• Mutations are spontaneous, random changes in the genetic material due to a mistake in replication and they can form new alleles when a genetic material is duplicated during reproduction.

  A mutation can change a genotype but does not always lead to a change in the phenotype.