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→Allopatric speciation
The individuals in the separated area are exposed to different selection pressures than the rest of their species and, over time, their morphology, physiology and biochemistry change significantly so that they are now unable to produce fertile offspring when interbred with the original population.
The individuals in the separated area are exposed to different selection pressures than the rest of their species and, over time, their morphology, physiology and biochemistry change significantly so that they are now unable to produce fertile offspring when interbred with the original population.
An excellent example of Allopatric speciation occurring within our lifetime and within the borders of the United States would be the Ensantina Salamander ((Ensatina eschscholtzi)). A lung less salamander native to the pacific coast from British Columbia, Canada to Southern California this amphibian originates from a single population and all subspecies are able to interbreed as the population moves from North to South or South to North depending on your vantage point. The interesting point is that there is a black zone, a meeting point near ((Mount Palomar)) outside of San Diego, California. This black zone is an area where the daughter population meets the parent population and through the processes of natural selection the genetic differences between the two populations are so great that the subsequent species can no longer interbreed. This is in fact an example of speciation through natural selection and it can be said that the Ensantina Salamander is in fact living proof of Darwinian Evolution.
DNA and enzymatic evidence is currently being investigated to determine the point at which the two species of this amphibian should be delineated.
===Peripatric Speciation===
===Peripatric Speciation===