Peripatric speciation

Peripatric speciation is a specific type of allopatric speciation that happens when a small population becomes isolated on the periphery of the parent population's range. Because the isolated group is very small (a "founder" population), genetic drift and unique selection pressures can lead to rapid differences and speciation.

• Think of peripatric speciation as a "founder effect" scenario: a few individuals colonize a new, isolated habitat (like an island or remote area on the edge of the range). The small population size means random genetic changes (drift) can have a big effect.
• Since peripatric is basically a special case of allopatric speciation, geographic isolation is still at play -- the difference is the emphasis on the small population size and its consequences (loss of genetic variation, drift).
• Unique traits in the small group can become fixed (common) quickly just by chance. This can lead to the new population being genetically and sometimes morphologically distinct from the original population fairly fast.

• Exam questions might describe a scenario where a few members of a species are isolated and start a new population (e.g., island colonizers). That setup is classic peripatric speciation -- look for keywords like "founder population" or "small isolated colony".
• Beware confusion: peripatric vs allopatric -- both involve geographic separation, but peripatric highlights a tiny offshoot population. If a question mentions strong genetic drift or founder effect, peripatric is the likely answer.
• For example, suppose a storm blows a handful of insects to a new island. Over time they become a new species. The small founding number (and isolation) makes this peripatric speciation.