Wild type (or wildtype abbreviated wt) refers to the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard, "normal" allele at a locus, in contrast to that produced by a non-standard, "mutant" allele. It is now appreciated that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general; however, the most prevalent allele – e.g., the one with the highest gene frequency is the one deemed as wild-type.[1]
The concept of wild type is useful in some experimental organisms such as fruit flies Drosophila melanogaster, in which the standard phenotypes for features such as eye color or shape and wing form are known to be altered by particular gene mutations that produce distinctive phenotypes, such as "apricot" "bar eyes" or "vestigial wings." "Wild type" alleles are indicated with a "+" superscript, for example B+ and vg+ for round eyes and full-size wings, respectively.