Extent of breeding isolation was estimated by two different sources among the Yanadi tribe, who inhabit different geographical regions and show wide cultural differences.
The estimate based on marriage frequency shows the formation of more or less well defined regional breeding populations, whereas the estimate based on surname frequency indicates past migration, gene flow and common affinity between regional populations. Both the sources consistantly show the process of fission, but the surnames are more useful and advantageous in defining the breeding isolation among the Yanadis.