Secondly, areas now continuous must often have existed within the recent period as isolated portions, in which many forms, more especially among the classes which unite for each birth and wander much, may have separately been rendered sufficiently distinct to rank as representative species.
Bigarrenik, kasu askotan gaur etengabeak diren eskualdeak oraintsuko aldietan zati isolatu izan bide dira, eta haietan forma asko, bereziki jaiotza bakoitzerako batzen diren eta batera eta bestera asko ibiltzen direnen artean, espezie errepresentagarritzat sailkatzeko bezain ezberdin bilakatu dira zein bere aldetik.