As the plants and animals migrated southward, they will have become mingled in the one great region with the native American productions, and would have had to compete with them; and in the other great region, with those of the Old World.
Hegorantz migratzean, landare eta animaliek Amerikako bertako ekoizkinekin nahasiko ziren eskualde zabal batean, eta haiekin norgehiagoka egin beharko zuten; eta beste eskualde zabalean mundu zaharrekoekin.