CHANGES IN THE GENETIC STRUCTURE OF A VALLEY IN THE PYRENEES (CATALONIA, SPAIN).

Abstract

In some situations the use of isonymy is the best strategy for studying the genetic structure of a population and its biological history. In this study different population parameters were calculated for one of the most isolated valleys in the Pyrenees - the region of the Alta Ribagorça in Catalonia, Spain. Surnames from marriage records covering the continuous period from 1638 to 1988 were used. From 1950 onwards this region underwent important social, economic and biological changes related to the introduction of hydroelectric and mining industries, and the change from livestock farming to a society based on services. Two periods were analysed (1638-1950 and 1951-1988) allowing population changes that occurred in the region to be determined. The study focused on calculating the number of surnames by gender, diversity index (H), population sub-structure (RP-RPr)/RPr and inbreeding coefficient (F t) and detection of possible genetic barriers. The results demonstrate the importance that geography initially had in shaping the genetic structure of the population and how this was gradually replaced by other parameters such as roads or the social and economic importance of towns. An interesting phenomenon is that inbreeding has traditionally been associated with rural life, isolation and endogamy. However, for the Alta Ribagorça it was observed that in the second period, 1951-1988, inbreeding mainly depended on the composition of migrant groups and the reaction of the native population to the arrival of migrants from outside the region.