sibling species

biology

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July 13, 2026

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Sibling species are two or more species that are nearly indistinguishable morphologically. This phenomenon occurs during speciation, the process by which new species arise.12

Speciation can happen through genetic divergence, where populations become so different they can no longer interbreed. Reproductive isolation, which prevents interbreeding, can arise as a byproduct of this divergence or be directly promoted by natural selection. Sibling species represent a stage where natural selection has separated incipient species, making them reproductively isolated but still morphologically similar.32

Examples of reproductive isolation include temporal isolation, where species breed at different times. This can occur in plants that flower at different times of day or in different seasons, or in animals like cicadas that emerge in different year cycles.4

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species
Speciation
…selection separates incipient species into sibling species, which do not mate at all but which in morphology, or structure and form, are nearly indistinguishable. Sibling species then evolve into morphologically (and taxonomically) different species. Because it is often difficult to distinguish between subspecies and stable species, another criterion has been…
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…selection separates incipient species into sibling species, which do not mate at all but which in morphology, or structure and form, are nearly indistinguishable. Sibling species then evolve into morphologically (and taxonomically) different species. Because it is often difficult to distinguish between subspecies and stable species, another criterion has been…
Read More