sympatric speciation

biology

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July 14, 2026

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Sympatric speciation is a controversial theory in evolutionary biology that describes the formation of new species within the same geographic area. Unlike allopatric speciation, which involves geographic isolation, sympatric speciation occurs when reproductive isolation arises within a single, interacting population.1

This process can be difficult to explain because it requires genetic divergence without physical separation. However, examples have been observed in apple maggot flies, where a subset of the population adapted to a new host plant (domesticated apples), leading to reproductive isolation from flies that continued to use hawthorns. Sympatric speciation can also be driven by factors like sexual selection and ecological specialization, as seen in some cichlid fish populations. In some cases, speciation can occur rapidly, termed "quantum speciation," often initiated by chromosomal mutations, as observed in certain plants and rodents.12

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speciation
Sympatric speciation
…alternative to allopatric speciation is sympatric speciation, in which reproductive isolation occurs within a single population without geographic isolation. In general, when populations are physically separated, some reproductive isolation arises. How genetic divergence can happen within a population of individuals that are continually interacting with one another is usually difficult…
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…alternative to allopatric speciation is sympatric speciation, in which reproductive isolation occurs within a single population without geographic isolation. In general, when populations are physically separated, some reproductive isolation arises. How genetic divergence can happen within a population of individuals that are continually interacting with one another is usually difficult…
Read More

apodiform
Ecology
…chiefly in the tropics that sympatric species (that is, those whose ranges overlap), sometimes closely related, may be found. Although there may be some altitudinal and other ecological separation of sympatric species, virtually nothing is known about possible partition of environmental resources among swifts; as many as three closely similar…
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…chiefly in the tropics that sympatric species (that is, those whose ranges overlap), sometimes closely related, may be found. Although there may be some altitudinal and other ecological separation of sympatric species, virtually nothing is known about possible partition of environmental resources among swifts; as many as three closely similar…
Read More

Virginia opossum
…where it occurs together (sympatry) with the common opossum. The coarse coat of long guard hair overlying the shorter, dense underfur may be either pale gray (gray phase) or mainly black (black phase). Rare in the north, black-phase individuals are more common in the southern United States and farther…
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…where it occurs together (sympatry) with the common opossum. The coarse coat of long guard hair overlying the shorter, dense underfur may be either pale gray (gray phase) or mainly black (black phase). Rare in the north, black-phase individuals are more common in the southern United States and farther…
Read More