I had found again and again that the most aberrant population of a species - often having reached species rank, and occasionally classified even as a separate genus - occurred at a peripheral location, indeed usually at the most isolated peripheral location.

ISBN 0-674-63906-5. In 1939 he was elected a Corresponding Member of the Royal Australasian Ornithologists Union. 1007/BF01640607.

Ernst Mayr approached the problem with a new definition for the concept of species. Ernst Walter Mayr (July 5 1904 – February 3 2005) was one of the 20th century's leading evolutionary biologists.