It is, for instance, almost certain that our dogs are descended from several wild stocks; yet, with perhaps the exception of certain indigenous domestic dogs of South America, all are quite fertile together;
Ia ziurra da, adibidez, gure txakurrak basa-enbor ezberdinetatik etorriak direla; hala ere, beharbada Hego Amerikako bertako etxe-txakur batzuk salbu, beste guztiak beren artean erabat ugalkorrak dira;