The Geography as a Regulator of Genetic Flow and Genetic Structure in Andorra

The Principality of Andorra is one of the smallest states in Europe. Traditionally its economy has been based on the agriculture and cattle ranch although in the last decades it has developed an important tourist activity that has become a collector of emigrants. The origin of marriage consorts has been analyzed in the six parishes that have traditionally constituted the Principality. In total, there have been 10,208 marriages covering a continuous period from 1606 to 1960. From this information, two migration matrices have been constructed, one general and one intra-population. The study of the first one shows the existence of a male migration to long distance, mainly from the nearby Catalan provinces. It also shows that the main parameter that regulates migration is geography and that it indirectly defines the language’s performance and political boundaries as the genetic filters. For the study of the intrapopulation matrix, two methods have been used. On the one hand, a tree has been constructed and has been linked to Principal Component Analysis (PCA). Different matrices have also been tested by applying the Mantel test. The results indicate that there is no asymmetry in the mobility of men and women in an intra-population level, a result that is justified by the demographic and social structure of the small population centers of the Pyrenees. It is also shown that geography is the main governing factor travel within the Principality. And finally, we can observe the existence of a genetic substructure in the Andorran population marked again by geography