Dictionary > Dumb-bell model

Dumb-bell model

It is a phenomenon in evolution in which ancestral population is divided into two fairly equal halves.
The same sequence of divergence of the subsequent meeting of the two populations will undergo speciation by subdivision.
One basis that is more evident on this model is that the separation of population would be isolated at the edge of a species range of barrier that divides the whole and the other basis is the pattern of geographic variation of modern species.
This is one model of allopatric speciation which represents the vital evolutionary process. Ring species give clear indication for its possibility but the evidence comes from the general existence and degree of geographic variation in all species and theoretical chance that reproductive isolation could evolve as part of the genetic divergence in an isolated allopatric population.
In case of two populations that have been move away in allopatry and consequently re-encounter each other in another geographical location, the gene flows become supplementary part as selection might strengthen any isolation between populations. On the other hand gene flow will perform to equalize the gene frequencies.
• peripheral isolate model
See also:
allopatric speciation
gene flow
gene frequency

You will also like...


Stems primarily provide plants structural support. This tutorial includes lectures on the external form of a woody twig ..

Cambial cells
Plant Tissues

Plant organs are comprised of tissues working together for a common function. The different types of plant tissues are m..

Electromagnetic spectrum of a brain
Sleep and Dreams – Neurology

While learning and intelligence are associated with the functions of a conscious mind, sleep and dreams are activities o..

kinesin motor proteins transporting molecules across microtubules
Movement of Molecules Across Cell Membranes

Molecules move within the cell or from one cell to another through different strategies. Transport may be in the form of..

Cell Respiration
Cell Respiration

Cell respiration is the process of creating ATP. It is "respiration" because it utilizes oxygen. Know the different stag..

An artistic depiction of Dunkleosteus fish

The sea was teeming with life. Eventually, through reproduction and continued variation, fish came about. There are over..