Brief communication: coexistence of two distinct patterns in the surname structure of Sicily

The extent of variation in the migratory movements that occurred in Sicily was evaluated using surname data taken from the telephone directories of the 390 communes of the island. The surname distribution of each commune was linearized by a log-log transformation, and a significant fit to a linear regression model was found in almost all cases. Interestingly, the slope of the regression line appeared to be a sensitive indicator of the different level of isolation associated with each Sicilian commune. By this approach, two distinct groups of communes, showing a higher or lower degree of isolation, were obtained, and two independent analyses of the surname structure of Sicily were carried out. A first multidimensional scaling analysis, based on the more isolated communes, yielded evidence for a more ancient pattern, characterized by a geographical gradient along the east-west axis. The same analysis, addressed to the less isolated communes, instead highlighted a wide network of interactions between geographically distant zones of the island. The fitting of the surname distribution to the log-log model allowed for the detection of a narrow subset of 35 Sicilian communes, whose significantly higher degree of isolation was statistically proved by the parallelism test. We believe that a genetic analysis focused on such specific zones of the island could reveal ancient patterns of differentiation, thus helping to answer the controversial question of the genetic history of Sicily.