According to present-day concepts of variation and speciation, Andersen's criteria are artificial.
In fact, isolation is a most important factor in speciation of insular populations (Baker, 1951:55).
Additional remarks on the distribution of this species are in the section on Zoogeography and speciation.
Natural selection plus geographical and ecological isolation has undoubtedly been operative in speciation and in subspeciation.
The process of speciation within insular populations has been discussed by many authors.
Isolation of small populations is probably the most influential factor in the process of speciation in insular organisms.
speciation spe·ci·a·tion (spē'shē-ā'shən, -sē-)
The evolutionary formation of new biological species, usually by the division of a single species into two or more genetically distinct ones.
The formation of new biological species by the development or branching of one species into two or more genetically distinct ones. The divergence of species is thought to result primarily from the geographic isolation of a population, especially when confronted with environmental conditions that vary from those experienced by the rest of the species, and from the random change in the frequency of certain alleles (known as genetic drift). According to the theory of evolution, all life on Earth has resulted from the speciation of earlier organisms. See also adaptive radiation.