Peripatric speciation

Peripatric speciation is a mode of speciation in which a new species forms from a small population isolated at the periphery of a larger one. As in allopatric speciation, the isolated group is cut off from gene flow with the main population, but the defining difference is size: in peripatric speciation one population is much smaller than the other, whereas ordinary allopatric speciation typically separates two similarly sized populations, making peripatric speciation something of a specialized subset of allopatric speciation. Ernst Mayr first described the pattern in 1954 from kingfishers of the species Tanysiptera galatea, whose mainland populations were fairly uniform in appearance while populations on surrounding islands had diverged noticeably, an early clue to how small, isolated populations can give rise to distinct forms.