Candela L. Hernández

Human maternal heritage in Andalusia (Spain): its composition reveals high internal complexity and distinctive influences of mtDNA haplogroups U6 and L in the western and eastern side of region

BackgroundThe archeology and history of the ancient Mediterranean have shown that this sea has been a permeable obstacle to human migration. Multiple cultural exchanges around the Mediterranean have taken place with presumably population admixtures. A gravitational territory of those migrations has been the Iberian Peninsula. Here we present a comprehensive analysis of the maternal gene pool, by means of control region sequencing and PCR-RFLP typing, of autochthonous Andalusians originating from the coastal provinces of Huelva and Granada, located respectively in the west and the east of the region.ResultsThe mtDNA haplogroup composition of these two southern Spanish populations has revealed a wide spectrum of haplogroups from different geographical origins. The registered frequencies of Eurasian markers, together with the high incidence and diversification of African maternal lineages (15% of the total mitochondrial variability) among Huelva Andalusians when compared to its eastwards relatives of Granada and other Iberian populations, constitute relevant findings unknown up-to-date on the characteristics of mtDNA within Andalusia that testifies a female population substructure. Therefore, Andalusia must not be considered a single, unique population.ConclusionsThe maternal legacy among Andalusians reflects distinctive local histories, pointing out the role of the westernmost territory of Peninsular Spain as a noticeable recipient of multiple and diverse human migrations. The obtained results underline the necessity of further research on genetic relationships in both sides of the western Mediterranean, using carefully collected samples from autochthonous individuals. Many studies have focused on recent North African gene flow towards Iberia, yet scientific attention should be now directed to thoroughly study the introduction of European genes in northwest Africa across the sea, in order to determine its magnitude, timescale and methods, and to compare them to those terrestrial movements from eastern Africa and southwestern Asia.

The Andalusian population from Huelva reveals a high diversification of Y-DNA paternal lineages from haplogroup E: Identifying human male movements within the Mediterranean space

Abstract Background: Gene flow among human populations is generally interpreted in terms of complex patterns, with the observed gene frequencies being the consequence of the entire genetic and demographic histories of the population. Aims: This study performs a high-resolution analysis of the Y-chromosome haplogroup E in Western Andalusians (Huelva province). The genetic information presented here provides new insights into migration processes that took place throughout the Mediterranean space and tries to evaluate its impact on the current genetic composition of the most southwestern population of Spain. Subjects and methods: 167 unrelated males were previously typed for the presence/absence of the Y-chromosome Alu polymorphism (YAP). The group of YAP (+) Andalusians was genotyped for 16 Y-SNPs and also characterized for 16 Y-STR loci. Results: The distribution of E-M81 haplogroup, a Berber marker, was found at a frequency of 3% in our sample. The distribution of M81 frequencies in Iberia seems to be not concordant with the regions where Islamic rule was most intense and long-lasting. The study also showed that most of M78 derived allele (6.6%) led to the V13* subhaplogroup. We also found the most basal and rare paragroup M78* and others with V12 and V65 mutations. The lineage defined by M34 mutation, which is quite frequent in Jews, was detected as well. Conclusions: The haplogroup E among Western Andalusians revealed a complex admixture of genetic markers from the Mediterranean space, with interesting signatures of populations from the Middle East and the Balkan Peninsula and a surprisingly low influence by Berber populations compared to other areas of the Iberian Peninsula.

Early Holocenic and Historic mtDNA African Signatures in the Iberian Peninsula: The Andalusian Region as a Paradigm

Determining the timing, identity and direction of migrations in the Mediterranean Basin, the role of “migratory routes” in and among regions of Africa, Europe and Asia, and the effects of sex-specific behaviors of population movements have important implications for our understanding of the present human genetic diversity. A crucial component of the Mediterranean world is its westernmost region. Clear features of transcontinental ancient contacts between North African and Iberian populations surrounding the maritime region of Gibraltar Strait have been identified from archeological data. The attempt to discern origin and dates of migration between close geographically related regions has been a challenge in the field of uniparental-based population genetics. Mitochondrial DNA (mtDNA) studies have been focused on surveying the H1, H3 and V lineages when trying to ascertain north-south migrations, and U6 and L in the opposite direction, assuming that those lineages are good proxies for the ancestry of each side of the Mediterranean. To this end, in the present work we have screened entire mtDNA sequences belonging to U6, M1 and L haplogroups in Andalusians—from Huelva and Granada provinces—and Moroccan Berbers. We present here pioneer data and interpretations on the role of NW Africa and the Iberian Peninsula regarding the time of origin, number of founders and expansion directions of these specific markers. The estimated entrance of the North African U6 lineages into Iberia at 10 ky correlates well with other L African clades, indicating that U6 and some L lineages moved together from Africa to Iberia in the Early Holocene. Still, founder analysis highlights that the high sharing of lineages between North Africa and Iberia results from a complex process continued through time, impairing simplistic interpretations. In particular, our work supports the existence of an ancient, frequently denied, bridge connecting the Maghreb and Andalusia.

Y-STR genetic diversity in autochthonous Andalusians from Huelva and Granada provinces (Spain)

Seventeen Y-chromosomal short tandem repeats (STRs) were analyzed in 347 healthy, unrelated, autochthonous males from the Andalusian provinces of Huelva (N=167) and Granada (N=180). AmpFlSTR Y-filer PCR Amplification kit (Applied Biosystems) was used to type the Y-STR markers. A total of 156 and 166 different haplotypes for the 17 Y-STR set were detected in Huelva, and Granada, respectively. The same haplotype diversity was found for both samples (0.998±0.001), and the overall discrimination capacity was 0.904. The most common minimal haplotype (DYS19, DYS389 I, DYS389 II, DYS390, DYS391, DYS392, DYS393) in both subpopulations was 14-13-16-24-11-13-13, which is also the most frequent haplotype among Atlantic European populations. Comparison analysis using pairwise R(ST) values and Analysis of Molecular Variance (AMOVA) revealed a significant genetic distance between our Andalusian samples and other ones from the northern Iberian fringe (including Basque and Pyrenean populations). However, results from the multi-dimensional scaling analysis (MDS) yielded a well-defined group of Iberian populations separated from the other Mediterranean clusters observed.

Surnames and Y-chromosomal markers reveal low relationships in Southern Spain.

A sample of 416 males from western and eastern Andalusia has been jointly analyzed for surnames and Y-chromosome haplogroups and haplotypes. The observed number of different surnames was 222 (353 when the second surname of the Spanish system of naming is considered). The great majority of recorded surnames have a Castilian-Leonese origin, while Catalan or Basque surnames have not been found. A few Arab-related surnames appear but none discernible of Sephardic-Jewish descent. Low correlation among surnames with different population frequencies and Y-chromosome markers, at different levels of genetic resolution, has been observed in Andalusia. This finding could be explained mainly by the very low rate of monophyletic surnames because of the historical process of surname ascription and the resulting high frequencies of the most common Spanish surnames. The introduction of surnames in Spain during the Middle Ages coincided with Reconquest of the territories under Islamic rule, and Muslims and Jews progressively adopted the present male line surname system. Sampled surnames and Y-chromosome lineages fit well a power-law distribution and observed isonymy is very close to that of the general population. Besides, our data and results show that the reliability of the isonymy method should be questioned because of the high rate of polyphyletic surnames, even in small geographic regions and autochthonous populations. Random isonymy would be consistently dependent of the most common surname frequencies in the population.

The distribution of mitochondrial DNA haplogroup H in southern Iberia indicates ancient human genetic exchanges along the western edge of the Mediterranean

BackgroundThe structure of haplogroup H reveals significant differences between the western and eastern edges of the Mediterranean, as well as between the northern and southern regions. Human populations along the westernmost Mediterranean coasts, which were settled by individuals from two continents separated by a relatively narrow body of water, show the highest frequencies of mitochondrial haplogroup H. These characteristics permit the analysis of ancient migrations between both shores, which may have occurred via primitive sea crafts and early seafaring. We collected a sample of 750 autochthonous people from the southern Iberian Peninsula (Andalusians from Huelva and Granada provinces). We performed a high-resolution analysis of haplogroup H by control region sequencing and coding SNP screening of the 337 individuals harboring this maternal marker. Our results were compared with those of a wide panel of populations, including individuals from Iberia, the Maghreb, and other regions around the Mediterranean, collected from the literature.ResultsBoth Andalusian subpopulations showed a typical western European profile for the internal composition of clade H, but eastern Andalusians from Granada also revealed interesting traces from the eastern Mediterranean. The basal nodes of the most frequent H sub-haplogroups, H1 and H3, harbored many individuals of Iberian and Maghrebian origins. Derived haplotypes were found in both regions; haplotypes were shared far more frequently between Andalusia and Morocco than between Andalusia and the rest of the Maghreb. These and previous results indicate intense, ancient and sustained contact among populations on both sides of the Mediterranean.ConclusionsOur genetic data on mtDNA diversity, combined with corresponding archaeological similarities, provide support for arguments favoring prehistoric bonds with a genetic legacy traceable in extant populations. Furthermore, the results presented here indicate that the Strait of Gibraltar and the adjacent Alboran Sea, which have often been assumed to be an insurmountable geographic barrier in prehistory, served as a frequently traveled route between continents.

New insights into the distribution of APOE polymorphism in the Iberian Peninsula. The case of Andalusia (Spain)

Abstract Background: The APOE gene has received much attention due to the remarkable spatial variation patterns of some of its genotypes and alleles in human populations and to its relevance in biomedicine. Aim: This work was addressed to investigate the extent of APOE polymorphism between autochthonous Andalusians originating from Huelva and Granada provinces. No data on this marker in these southern Spanish coastal populations are available up to date. Subjects and methods: This study used genomic DNA from healthy, unrelated Andalusians of both sexes (n = 322). All samples were genotyped for two SNPs, rs429358 and rs7412, which determine the three APOE alleles: ε2, ε3 and ε4. For analyses, a TaqMan-based technique was applied using a RT-PCR. Comparisons with other Mediterranean populations were performed based on multivariate analysis. Results: A relatively high frequency of ε4 in Granada (eastern Andalusia), as well as a low ε2 frequency in Huelva (western Andalusia) were observed. The finding that ε4 allele in Southern Spain and Portugal is higher than expected given its geographical location poses an interesting question for this study, given the well-established APOE-ε4 gradient in Europe. Conclusion: This population study may represent useful information for further prospective anthropological and molecular genetic studies focused on unravelling the relationship between population genetic composition and specific human diseases.

Immunoglobulin genes in Andalusia (Spain). Genetic diversity in the Mediterranean space

Andalusia is the most densely populated region of Spain since ancient times, and has a rich history of contacts across the Mediterranean. Earlier studies have underlined the relatively high frequency of the Sub-Saharan GM 1,17 5* haplotype in western Andalusia (Huelva province, n=252) and neighbouring Atlantic regions. Here, we provide novel data on GM/KM markers in eastern Andalusians (n=195) from Granada province, where African GM*1,17 5* frequency is relatively high (0.044). The most frequent GM haplotypes in Andalusia parallel the most common in Europe. Altogether, these data allow us to gain insight into the genetic diversity of southern Iberia. Additionally, we assess population structure by comparing our Iberian samples with 41 Mediterranean populations. GM haplotype variation across the Mediterranean reflects intense and complex interactions between North Africans and South Europeans along human history, highlighting that African influence over the Iberian Peninsula does not follow an isotropic pattern.