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Although animals are thought to be more mobile than plants, pollen and seeds may be carried great distances by animals, water or wind. When gene flow is impeded, there can be an increase in inbreeding, measured by the inbreeding coefficient (F) within a population. For example, many island populations have low rates of gene flow due to ...
Different chromosomes appear to have split at different times, possibly over as much as a 4-million-year period, indicating a long and drawn out speciation process with large-scale gene flow events between the two emerging lineages as recently as 6.3 to 5.4 million years ago, according to Patterson et al. (2006). [21]
A ring species is an alternative model to allopatric speciation, "illustrating how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" [11] However, Jerry Coyne and H. Allen Orr point out that rings species more closely model parapatric speciation. [4]
Doebeli and Dieckmann developed a mathematical model that suggested that ecological contact is an important factor in parapatric speciation and that, despite gene flow acting as a barrier to divergence in the local population, disruptive selection drives assortative mating; eventually leading to a complete reduction in gene flow. This model ...
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.
Gene flow is the exchange of genes between populations or species, breaking down the structure. Examples of gene flow within a species include the migration and then breeding of organisms, or the exchange of pollen. Gene transfer between species includes the formation of hybrid organisms and horizontal gene transfer. Population genetic models ...
Criterion 2 considers the gene flow between populations, measured by F ST. A high degree of differentiation between two populations among genes that provide no adaptive advantage to either population (known as neutral markers) implies a lack of gene flow, showing that random drift has occurred in isolation from other populations. Very few ...
[46] [47] Modified versions of these tests can be used to infer introgressed genomic regions, [48] the direction of gene flow [49] [50] or the amount of gene flow. [47] For datasets with a large number of taxa it may be difficult to compute all possible test of hybridization. In such cases, graph construction methods may be better suited.