Does the morphological diversity of a group of organisms positively correlate with the presumed frequency of peripatric speciation?
The theory of frozen plasticity suggests that important changes in the phenotype (e.g., morphology) of species occurs only in evolutionarily plastic species, i.e., those species which originated by peripatric speciation (for example, by colonization of an oceanic island) rather than by allopatric speciation (for example, by splitting the original geographic area of a species into two parts of similar size by a new geographic barrier). Biogeographical data suggest that the rate of anagenesis on islands is really higher than on the mainland. Also, many taxa, the most „strange“ species, usually occur on oceanic islands rather than on the mainland. The higher frequency of peripatric speciation on islands than on the mainland can be the clue to the observed phenomena.