BioConcepts

isolationisolation (fr.); Isolation (ger.)

• 1) The limitation or prevention of interbreeding between groups of plants or animals by geographical, ecological, seasonal, or other factors, leading to the development of new species or varieties. (OED)
  category evolution

  1835

  Breeds […] may possibly be sometimes formed by accidental isolation in a state of nature

  Blyth, E. (1835). An attempt to classify the “varieties” of animals. Mag. Nat. Hist. 8, 40-53: 45.

  1836

  M. Mirbel has similarly had occasion to remark different instances of isolation […] ›Mountainous countries‹, he says, ›possess many species of limited or solitary habitats, which confine themselves to the heights, and are never found on the plains

  Webb, P.B. & Berthelot, S. (1836). Histoire naturelle des Iles Canaries (engl.: Vegetation of the Canary Islands. In: Hooker, W.J. (ed). Companion to the Botanical Magazine 1, 332-344: 342).

  1837

  If species made by isolation, then their distribution (after physical changes) would be in rays – from certain spots

  Darwin, C. (1837). Notebook B: 155 (http://darwinonline.org.uk/).

  1859

  Isolation […] is an important element in the process of natural selection

  Darwin, C. (1859). On the Origin of Species: 104.

  1961

  the degree of differentiation within a species is directly proportional to the degree of isolation of its separate parts

  Četverikov, S.S. (1961). On certain aspects of the evolutionary process from the standpoint of modern genetics. Proc. Amer. Philos. Soc. 105, 167-95): 180.

• 2) The lonely position of a taxonomical group in the system of animals. (HWB)
  

  1801

  l’isolation plus ou moins remarquable de beaucoup d’espèces, de certains genres et même de quelques petites familles

  Lamarck, J.-B. de (1801). Système des animaux sans vertèbres: 17; cf. 28.