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Patterns of DNA sequence diversity and genetic structure after a range expansion: lessons from the infinite‐island model
Author(s) -
Excoffier Laurent
Publication year - 2004
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2003.02004.x
Subject(s) - biology , range (aeronautics) , population , pairwise comparison , genetic diversity , demographic history , diversity (politics) , evolutionary biology , fixation (population genetics) , mitochondrial dna , sequence (biology) , statistics , genetics , mathematics , demography , gene , materials science , sociology , anthropology , composite material
It has been long recognized that population demographic expansions lead to distinctive features in the molecular diversity of populations. However, recent simulation results have suggested that a distinction could be made between a pure demographic expansion in an unsubdivided population, and a range expansion in a subdivided population, both leading to a large increase in the total number of the individuals. In order to better characterize the effect of a range expansion, I introduce a simple model of instantaneous expansion under an infinite‐island model, under which I derive the distribution of the number of mutation differences between pairs of genes (the mismatch distribution), the heterozygosity, the average number of pairwise difference, and the fixation index F ST . These derivations are checked against simulations, and are shown to lead to results qualitatively similar to those one would obtain after a range expansion in a 2‐dimensional stepping‐stone model. I then apply these results to estimate immigration rates in hunter‐gather and post‐Neolithic human populations from patterns of mitochondrial (mtDNA) diversity. Potential problems with this estimation procedure are also discussed.