A model proposing that speciation occurs in small populations isolated on the periphery of the distribution of the parental population, as opposed to parapatric speciation (q.v.). The isolated populations may undergo shifts in their gene frequencies under the influence of genetic drift. This is most likely to occur if new populations arise from a few founder individuals and no gene flow occurs between the isolates and the main population. Consequently the most rapid evolutionary changes do not occur in widespread populous species, but in small founder populations. See Chronology C, 1954, Mayr; founder effect.
Subjects: Genetics and Genomics.