WANI Dictionary

Founder effect

Founder effect refers to the phenomenon that occurs after a population is founded by a small number of individuals. Typically, allele frequencies in the new population differ from those in the original population, reflecting the genetic composition of the founders.

Definitions in the literature

• the result of an event in which an isolated population is founded by a small number of individuals; may result in genetic drift if allele frequencies in the founder population are by chance different from those of the parent population [1].
• After a small group of individuals found a new population, allele frequencies in the new population differ from those in the original population [2].
• The phenomenon occurring when a population is founded by a small sample of the entire species, perhaps just a handful of indhiduals. Chance dictates that these founder members will be genetically unrepresentative of the species as a whole, and that the genetic make-up of the new population will differ markedly from the main species population [3].