GENETIC-STRUCTURE OF GREEK SHEEP BREEDS

The genetic structure of nine Greek sheep breeds was studied on the ba sis of 20 gene systems. The main results obtained can be summarized as follows: 1. Nine of the 20 loci were found to be polymorphic; 2. The gene frequencies were significantly different between breeds at most o f the loci Investigated; 3. The deviation from genetic equilibrium obs erved at some loci could be attributed to genetic drift; 4. The averag e heterozygosity for the loci studied ranged between 12 and 18 %; 5. T he genetic distance between breeds ranged from 0.229 to 0.342; 6. The dendrogram for the phylogenetic relationships between the breeds is in good agreement with the breeds' geographic distribution in Greece and their historical origin; and 7. Effects of the gene systems on milk y ield were found only for some loci and breeds.