Figure 1.

(a) The resolution of ancestry inference in a local US population is dependent on the level of admixture in the population. For example, in a population of European Americans, the resolution of ancestry inference might range from continent (low resolution), when the local population is panmictic, to country (high resolution), when there is little or no admixture within the local population. (b) Initially, sink (US) and source (European) populations are coincident in genetic space as determined by methods such as PCA. (c) After some period of time, sink and source populations grow divergent because of genetic drift and admixture; the actual pattern of divergence in genetic space will vary depending on, at least, the level of admixture within the sink population.