Simulation of the rapid expansion of a breeding isolate starting with 20 or 40 founders indicates that a lethal gene present in one original founder can attain polymorphic frequencies up to .10. Migration into the isolate decreases the probability of a lethal gene attaining polymorphic frequencies, but these still occur at rather high frequencies. A model of population expansion through fission and the establishment of new populations by a few founders also shows that the entire set of populations can attain an average gene frequency that is minimally polymorphic.
Livingstone, Frank B.
"Simulation of the Founder Effect and its Role in the Determination of the Polymorphic Frequencies of Deleterious Qenes in Human Populations,"
1, Article 7.
Available at: https://digitalcommons.wayne.edu/humbiol/vol59/iss1/7