IBD (Isolation by Distance): A Program for Analyses of Isolation by Distance

The genetic similarity among individuals or populations can be ascertained using a number of statistical techniques (reviewed by Bohonak 1999; Neigel 1997; Roderick 1996; Slatkin 1985). When populations can be defined a priori, one option is to analyze genetic ‘‘isolation by distance’’ (sensu Wright 1943) by plotting the genetic similarity (or distance) among population pairs as a function of the geographic distance between those pairs. Slatkin (1993) suggested the genetic distance M (1/FST 1)/4 as an appropriate similarity measure, although other approaches are possible (e.g., Epperson and Li 1996). Qualitative and statistical analyses of isolation by distance can reveal much about population genetic…