Caracterización genética y dinámica evolutiva de las poblaciones de la provincia de Zamora

Abstract

The research developed in this Doctoral thesis is focused on the bioanthropologic characterisation of the current population of the Zamora province. The territory of the province of Zamora is located in the North-West side of the Iberian Northern plateau, with the Portuguese border on the west. Its heterogenic landscape allows defining six regions (Aliste, Bajo Duero, Benavente, Campos-Pan, Sanabria and Sayago). Taking a look on the history of the settlement of the area, a discontinuity in the population is observed for the period of the Islamic occupation of the Iberian Peninsula, although a posterior resettle was made by Northern Kingdoms. In addition, the area has suffered several demographic crises, as the current migratory depopulation. Taking into account the facts previously presented and the total absence of genetic studies in this area, the general aim of this study is to characterise the current population of the Zamora province through monoparent genetic markers: the no recombining region of the Y chromosome (NRY), the mitochondrial DNA molecule (mtDNA) and surnames. The specific goals are: 1) increase the knowledge about the genetic-historic events of the territory, making inferences in the precedence of the people; 2) analyse the effect of the political and natural boundaries in the genetic microdifferentiation of the province; 3) estimate whether the recent depopulation events are affecting the genetic diversity and 4) check the impact of ethnic-religious minorities, in the current genetic pool of the Zamora province. To accomplish the proposed objectives 236 samples for the NRY of the Y chromosome and 214 samples for the mtDNA of autochthonous individuals from the Zamora province were analysed. Moreover, surnames from 166.349 individuals were also analysed. The obtained results allowed concluding that: 1) The global genetic composition based on both NRY and mtDNA of the Zamora province corresponds to that expected "a priori", according to an Iberian population located in the Northern Plateau portion of the Iberian Peninsula, with a major presence of Palaeolithic haplogroups. 2) Different substructuring implemented analysis showed the differentiation of Aliste and Sayago regions, thus the microdifferentiation is not conditioned by the geographic boundaries. Moreover, considering the bordering regions, the analysis showed the importance of the Spanish-Portuguese boundary in the limiting of the genetic flow. 3) The recent depopulation events are not affecting the current genetic diversity as the observed values based on Y chromosome and mitochondrial data are very high considering the whole range detected in the Iberian Peninsula, being the highest detected in the regions of Aliste and Sayago. In this sense, consanguinity values based on surnames show medium values when compared to other populations from the Iberian Peninsula. 4) A noticeable presence of African and Near Eastern lineages is observed, its presence being focused respectively in the regions of Sayago and Aliste. The most reasonable origin for these influences would be the Islamic occupation of the Iberian Peninsula, for the African lineages and the presence of Sephardic communities in the area for the Near East lineages.