The formation of ring species might provide an explanation of how speciation can occur despite ongoing gene flow.
In a ring species, the ranges of multiple subspecies connect around a geographic barrier.
There is a long-standing hypothesis that Caribbean Junonia are a ring species [29,34], which is defined as a group of species or subspecies that exhibit a ring-like distribution such that the forms at the extreme ends of the range overlap .
Price, "Speciation by distance in a ring species," Science, vol.
He discusses polyploidy of plants and ring species
of birds to show how reproductive isolation--a necessary precondition for speciation--can occur.
He includes a variety of excellent examples, from retroviral insertions to "ring species
," which allow scientists to study speciation processes as they are happening.
The discovery of ring species
such as the Larus gulls described above, (the Californian Ensatina salamanders or the Himalayan Greenish Warblers) challenges the reductionist notion of species.
Key words.--Biogeography, cytochrome-b, evolutionary genetics, mitochondrial DNA, nucleotide sequence, Perognathus, restriction fragments, ring species, speciation.
A special case of geographic speciation is seen in ring species (polytypic species demonstrating circular overlap).
* Greenish warbler populations encircling the Tibetan Plateau were viewed as evidence of a long-sought evolutionary phenomenon called a ring species
Stebbins' concept of a polytypic ring species
was based on perceived primary intergradation between the sub-species where they met, with the exception of two instances of postulated secondary contact.
A new look at warblers in habitat that surrounds the Tibetan Plateau revives an old hope that the birds represent a long-sought evolutionary quirk called a ring species