Alternative Migration Models
In population genetics, 'migration'
is movement among populations, rather than
periodic movement of individuals between one place and
another.
(A) The Mainland / Island Model assumes that offshore islands receive unidirectional migration from the Mainland. (B) The Island Model assumes that a species is divided into multiple sub-populations, each of which is connected to all of the others (this resembles an island archipelago). (C) The alternative Stepping-Stone Model assumes that sub-populations are connected only to adjacent sub-populations, in a nearest-neighbor grid. (D) Path Model assumes that each sub-population is connected only to those on either side of it, in linear sequence. (E) A more complex model may use different allele frequencies q and different migration rates m to achieve more complex results.
The models are drawn so as to suggest land islands surrounded by water. They are however equally applicable to ponds / lakes connected by watercourses. Model D in is readily adapted to a Riverine model with unidirectional migration due to downstream flow.
(A) The Mainland / Island Model assumes that offshore islands receive unidirectional migration from the Mainland. (B) The Island Model assumes that a species is divided into multiple sub-populations, each of which is connected to all of the others (this resembles an island archipelago). (C) The alternative Stepping-Stone Model assumes that sub-populations are connected only to adjacent sub-populations, in a nearest-neighbor grid. (D) Path Model assumes that each sub-population is connected only to those on either side of it, in linear sequence. (E) A more complex model may use different allele frequencies q and different migration rates m to achieve more complex results.
The models are drawn so as to suggest land islands surrounded by water. They are however equally applicable to ponds / lakes connected by watercourses. Model D in is readily adapted to a Riverine model with unidirectional migration due to downstream flow.
Figures A, B, C, & D © 2013 by Sinauer; Text material © 2024 by Steven M. Carr