Abstract
The Turkish black rat “Rattus rattus” shows variation in coat colour corresponding to the occurrence of three subspecies with intermediate colour stages: Rattus rattus rattus, Rattus r. alexandrinus and Rattus r. frugivorus. Turkish black rat populations were divided geographically into six sub-populations: Rr1= Northwest Anatolia, Rr2= Central Anatolia, Rr3= Eastern Mediterranean, Rr4= Western Mediterranean, Rr5= Turkish Thrace, and Rr6= Black Sea region. Genetic variation was assessed using twenty two isoenzyme systems. Seven of twenty-two loci (Pgm-1, Hk, Me-M, G3pdh, Gpdh-1, Gpi, Fum-1 ) were found to be polymorphic. The mean value of F ST is found to be 0.073, indicating 7.3 % genetic variation among groups and suggesting the existence of a moderate differentiation between sub-populations of the Turkish black rat. Overall mean heterozygosity (Ho= direct count) for sub-populations was Ho= 0.020, ranging from 0.008 to 0.031. Nei’s measure of genetic distance showed that Rr2 and Rr6 were the most identical and sub-populations Rr1 and Rr5 had diverged the most.