According to this idea, although they’re currently important to define species’ geographical limits, rivers had nothing to do with the initial separation of that ancestral population.

In an admixed population, these causal variants will occur more frequently on chromosomal segments inherited from one or another ancestral population.

The first step consists in a description of an ancestral population of organisms.

First, the so-called founder effect occurs when founder populations bring only a subset of the genetic variation from their ancestral population.

All modern humans share the same origin from this single ancestral population.