WikipediaRead full entry Ensatina eschscholtzii (commonly known
by its genus name, Ensatina) is a complex of plethodontid
(lungless) salamanders found in coniferous forests, oak woodland
and chaparral from British Columbia, through Washington, Oregon,
across California (where all seven subspecies variations are
located), all the way down to Baja California in Mexico. As a
ring species  The Ensatina salamander has been described as a
ring species in the mountains surrounding the Californian
Central Valley. The complex forms a horseshoe shape around the
mountains, and though interbreeding can happen between each of
the 19 populations around the horseshoe, the Ensatina
eschscholtzii subspecies on the western end of the horseshoe
cannot interbreed with the Ensatina klauberi on the eastern end.
As such it is thought to be an example of incipient speciation,
and provides an illustration of "nearly all stages in a
speciation process" (Dobzhansky,1958). Richard Highton argued
Ensatina is a case of multiple species an