Canjin yanayi shine babban abinda ke taimakawa wajen samun damar yadda halittun dake doron kasa zasu sami ikon rayuwa cikin aminci, misali kifi a cikin ruwa mai sanyi yake rayuwarsa da zarar ruwan yayi dumi to shike nan ya shiga tsaka mai wuya. Haka nan dan adam shima bazai iya rayuwa a wani muhalli wadda halittar jikinsa bazata iya karbar yanayin ba, dole sai yanayin da kwayoyin halittar jikinsa zata iya karba.