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River barrier speciation occurs when a river is of sufficient size to provide a vicariance for allopatric speciation, or when the river is large enough to prevent or interfere with a genetic exchange between populations. Population division is initiated either when a river shifts into or forms within the range of a species that cannot cross it ...
In biogeography, geodispersal is the erosion of barriers to gene flow and biological dispersal (Lieberman, 2005.; [1] Albert and Crampton, 2010. [2]). Geodispersal differs from vicariance, which reduces gene flow through the creation of geographic barriers. [3]
Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other' and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model [1]: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
Speciation ultimately results due to the reproductive isolation between two populations. This can happen in a multitude of ways, a common mode of which is known as allopatric speciation. The geographic mode, where two species become physically isolated and unable to interbreed, allows for selection to act on both populations independently. Over ...
There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion.
A kulliyyāt (from Arabic: كلّيّات kulliyyāt; Persian: کلیات kolliyyât; Azerbaijani: külliyyat; Urdu: کلیات; Uzbek: kulliyat) is a collection of the poetry of any one poet. Cover of the 1872 translation of the works of Mirza Muhammad Rafi Sauda (1713–1781) Kulliyat is one of the principal collection forms of Urdu poetry ...
Urdu literature (Urdu: ادبیاتِ اُردُو, “Adbiyāt-i Urdū”) comprises the literary works, written in the Urdu language.While it tends to be dominated by poetry, especially the verse forms of the ghazal (غزل) and nazm (نظم), it has expanded into other styles of writing, including that of the short story, or afsana (افسانہ).
The formation of barriers to dispersal or gene flow between adjacent areas can isolate populations on either side of the emerging divide. The geographic separation and subsequent genetic isolation of portions of an ancestral population can result in allopatric speciation.