Do ring species exist?
While no perfect example exists, there are various different 'ring species' in nature where you have which species are able to interbreed with closely related populations, but there are least two &quot;end&quot; populations in the series. Examples include:

Alauda arvensis, A. japonica and A. gulgula: Species of Skylark birds that coexist around Central Asia





In central Asia, a northern form,, arvensis, a southern form,gulgula, and Oriental,japonica , coexist without interbreeding.These forms are separated
by a gap in distribution in northern China, but a morphologically intermediate
form, japonica, occurs in Japan. Northern japonica are similar to arvensis and
southern japonica resemble gulgula. -Ring species as bridges between microevolution and speciation


Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.




The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate &quot;how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…&quot; and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.