How much of the acclimatisation of species to any peculiar climate is due to mere habit, and how much to the natural selection of varieties having different innate constitutions, and how much to both means combined, is an obscure question.
Espezieek zeinnahi klima berezitara ekantzea zenbateraino den aztura hutsaren ondorio, zenbateraino sortzetiko osaera ezberdina duten aldakien hautespen naturalaren ondorio eta zenbateraino faktore bion konbinaketarena, ilun dagoen arazoa da.