Isolation by distance

Isolation by distance (IBD) is a term used to refer to the accrual of local genetic variation under geographically limited dispersal The IBD model is useful for determining the distribution of gene frequencies over a geographic region. Both dispersal variance and migration probabilities are variables in this model and both contribute to local genetic differentiation Isolation by distance is usually the simplest model for the cause of genetic isolation between populations. Evolutionary biologists and population geneticists have been exploring varying theories and models for explaining population structure. Ishida compares two important theories of isolation by distance and clarifies the relationship between the two. According to Ishida, Sewall Wright’s isolation by distance theory is termed ecological isolation by distance while Gustave Malécot’s theory is called genetic isolation by distance. Isolation by distance is distantly related to speciation. Multiple types of isolating barriers, namely prezygotic isolating barriers which includes isolation by distance, are considered to be the key factor in keeping populations apart limiting gene flow.