The phenotype of an organism that is most commonly observed in nature is called the

Wild type

Explanation:

It refers to the phenotype that is found in nature. Naturally the form that is commonly seen in nature and is used for experiment is this type only.

This concept is useful in many experiment as it can be used as a model organism. Example: Drosophila melanogaster.

Manipulation of genes produces different type of phenotype other than wild type which is not generally seen in the nature.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).