Simulation of the effects of changing population size on the genetic structure of Western Ireland

During the 1800's, the population of Ireland underwent a rapid increase and subsequent decrease in population size. The effects of this change upon population structure were assessed using a simulation of the isolation by distance model and comparing the results to those obtained assuming constant population size. These results indicate that changes in within-group genetic similarity (kinship) brought about by a rapid increase in population size are cancelled by the effects of a rapid decrease in population size. Parameters of the isolation by distance model are hardly affected by population size changes. These results suggest that violation of the assumption of constant population size for population structure models may not be that serious when population size changes rapidly and in both directions.