Mitochondrial DNA characterisation of European isolates: the Maragatos from Spain

Mitochondrial DNA analysis confirms that Maragatos from Spain are a genetically isolated human group. Genetic distances between Maragatos and the comparison samples are significantly different even with the León sample (P<0.001) which shares the same geographic area as the Maragatos. Although the north-African haplogroup U6 is present in them, their attributed Berber origin is weakened, as this haplogroup is also detected in surrounding populations with which, in addition, Maragatos have the smaller genetic distances. These U6 haplotypes are ascribed to a pre-historic African colonisation that influenced all the Iberian Peninsula. The presence of Neolithic haplogroups in this sample suggests that their isolation culture was not absolute until recent times.     

Joining the Pillars of Hercules: mtDNA Sequences Show Multidirectional Gene Flow in the Western Mediterranean

Phylogenetic analysis of mitochondrial DNA (mtDNA) performed in Western Mediterranean populations has shown that both shores share a common set of mtDNA haplogroups already found in Europe and the Middle East. Principal co‐ordinates of genetic distances and principal components analyses based on the haplotype frequencies show that the main genetic difference is attributed to the higher frequency of sub‐Saharan L haplogroups in NW Africa, showing some gene flow across the Sahara desert, with a major impact in the southern populations of NW Africa. The AMOVA demonstrates that SW European populations are highly homogeneous whereas NW African populations display a more heterogeneous genetic pattern, due to an east‐west differentiation as a result of gene flow coming from the East. Despite the shared haplogroups found in both areas, the European V and the NW African U6 haplogroups reveal the traces of the Mediterranean Sea permeability to female migrations, and allowed for determination and quantification of the genetic contribution of both shores to the genetic landscape of the geographic area. Comparison of mtDNA data with autosomal markers and Y‐chromosome lineages, analysed in the same populations, shows a congruent pattern, although female‐mediated gene flow seems to have been more intense than male‐mediated gene flow.     

MtDNA Profile of West Africa Guineans: Towards a Better Understanding of the Senegambia Region

The matrilineal genetic composition of 372 samples from the Republic of Guiné‐Bissau (West African coast) was studied using RFLPs and partial sequencing of the mtDNA control and coding region. The majority of the mtDNA lineages of Guineans (94%) belong to West African specific sub‐clusters of L0‐L3 haplogroups. A new L3 sub‐cluster (L3h) that is found in both eastern and western Africa is present at moderately low frequencies in Guinean populations. A non‐random distribution of haplogroups U5 in the Fula group, the U6 among the “Brame” linguistic family and M1 in the Balanta‐Djola group, suggests a correlation between the genetic and linguistic affiliation of Guinean populations. The presence of M1 in Balanta populations supports the earlier suggestion of their Sudanese origin. Haplogroups U5 and U6, on the other hand, were found to be restricted to populations that are thought to represent the descendants of a southern expansion of Berbers. Particular haplotypes, found almost exclusively in East‐African populations, were found in some ethnic groups with an oral tradition claiming Sudanese origin.     

Genetic Structure and Origin of Peopling in The Azores Islands (Portugal): The View from mtDNA

The Azores islands (Portugal), uninhabited when discovered by Portuguese navigators in the fifteenth century, are located in the Atlantic Ocean 1500 km from the European mainland. The archipelago is formed by nine islands of volcanic origin that define three geographical groups: Eastern (S. Miguel and Sta. Maria), Central (Terceira, Faial, Pico, Graciosa and S. Jorge) and Western (Flores and Corvo). To improve the genetic characterisation of the Azorean population, and to clarify some aspects related to the history of settlement, a study of mtDNA was conducted in the population of the archipelago. The HVRI region was sequenced and specific RFLPs were screened in 146 samples obtained from unrelated individuals with Azorean ancestry (50 from the Eastern group, 60 from the Central group, and 37 from the Western group). Samples were classified into haplogroups based on the information obtained from both sequencing and RFLP analysis. All the analyses performed support the idea that, in the whole group of islands, the majority of mtDNA lineages originated from the Iberian Peninsula, mainly from Portugal (mainland). However contributions from other European populations, especially from Northern Europe, cannot be disregarded. The values obtained for the various diversity parameters in the Azores archipelago indicate that the Azorean population, as a whole, does not exhibit the typical characteristics of an isolated population. The analysis of genetic data by groups of islands showed that the Western group exhibited particular features. The distribution of haplogroups in the Western group is very atypical, being significantly different from what is observed in the Eastern and Central groups. Furthermore, the diversity values are, in general, lower than those observed in other populations used for comparison. African haplogroups were found in all the groups of islands. Therefore the presence of Moorish and African slaves on the islands, as reported in historical sources, is supported by the mtDNA genetic data, especially in the Eastern group. The presence of Jews in the Central group is also supported by the mtDNA data. Neither historical nor genetic data (phylogeography of mtDNA) supports the idea of a differential settlement history for the Western group; however, it is represented in the phylogenies as an isolated branch. The effect of genetic drift, induced by the reduced population size since peopling occurred, has led to a very atypical distribution of haplogroups/haplotypes in this group of islands. We cannot ignore the influence of biodemographic and genetic processes, namely founder effect, genetic drift, migration, and even recent mutational events in the mtDNA lineages of the Azorean populations. Nevertheless, a great part of the variation in the Azorean mtDNA can be explained by the settlement history.     

Y-chromosome Lineages from Portugal, Madeira and Açores Record Elements of Sephardim and Berber Ancestry

A total of 553 Y‐chromosomes were analyzed from mainland Portugal and the North Atlantic Archipelagos of Açores and Madeira, in order to characterize the genetic composition of their male gene pool. A large majority (78–83% of each population) of the male lineages could be classified as belonging to three basic Y chromosomal haplogroups, R1b, J, and E3b. While R1b, accounting for more than half of the lineages in any of the Portuguese sub‐populations, is a characteristic marker of many different West European populations, haplogroups J and E3b consist of lineages that are typical of the circum‐Mediterranean region or even East Africa. The highly diverse haplogroup E3b in Portuguese likely combines sub‐clades of distinct origins. The present composition of the Y chromosomes in Portugal in this haplogroup likely reflects a pre‐Arab component shared with North African populations or testifies, at least in part, to the influence of Sephardic Jews. In contrast to the marginally low sub‐Saharan African Y chromosome component in Portuguese, such lineages have been detected at a moderately high frequency in our previous survey of mtDNA from the same samples, indicating the presence of sex‐related gene flow, most likely mediated by the Atlantic slave trade.     

Reduced genetic structure of the Iberian peninsula revealed by Y-chromosome analysis: implications for population demography

Europe has been influenced by both intra- and intercontinental migrations. Since the Iberian peninsula was a refuge during the Last Glacial Maximum, demographic factors associated with contraction, isolation, subsequent expansion and gene flow episodes have contributed complexity to its population history. In this work, we analysed 26 Y-chromosome biallelic markers in 568 chromosomes from 11 different Iberian population groups and compared them to published data on the Basques and Catalans to gain insight into the paternal gene pool of these populations and find out to what extent major demographic processes account for their genetic structure. Our results reveal a reduced, although geographically correlated, Y-chromosomal interpopulation variance (1.2%), which points to a limited heterogeneity in the region. Coincidentally, spatial analysis of genetic distances points to a focal distribution of Y-chromosome haplogroups in this area. These results indicate that neither old or recent Levantine expansions nor North African contacts have influenced the current Iberian Y-chromosome diversity so that geographical patterns can be identified.     

The Complex and Diversified Mitochondrial Gene Pool of Berber Populations

The mitochondrial DNA variation of 295 Berber-speakers from Morocco (Asni, Bouhria and Figuig) and the Egyptian oasis of Siwa was evaluated by sequencing a portion of the control region (including HVS-I and part of HVS-II) and surveying haplogroup-specific coding region markers. Our findings show that the Berber mitochondrial pool is characterized by an overall high frequency of Western Eurasian haplogroups, a somehow lower frequency of sub-Saharan L lineages, and a significant (but differential) presence of North African haplogroups U6 and M1, thus occupying an intermediate position between European and sub-Saharan populations in PCA analysis. A clear and significant genetic differentiation between the Berbers from Maghreb and Egyptian Berbers was also observed. The first are related to European populations as shown by haplogroup H1 and V frequencies, whereas the latter share more affinities with East African and Nile Valley populations as indicated by the high frequency of M1 and the presence of L0a1, L3i, L4*, and L4b2 lineages. Moreover, haplogroup U6 was not observed in Siwa. We conclude that the origins and maternal diversity of Berber populations are old and complex, and these communities bear genetic characteristics resulting from various events of gene flow with surrounding and migrating populations.     

Mitochondrial DNA Variability in Slovaks, with Application to the Roma Origin

To gain insight into the mitochondrial gene pool diversity of European populations, we studied mitochondrial DNA (mtDNA) variability in 207 subjects from western and eastern areas of Slovakia. Sequencing of two hypervariable segments, HVS I and HVS II, in combination with screening of coding region haplogroup-specific RFLP-markers, revealed that the majority of Slovak mtDNAs belong to the common West Eurasian mitochondrial haplogroups (HV, J, T, U, N1, W, and X). However, a few sub-Saharan African (L2a) mtDNAs were detected in a population from eastern part of Slovakia. In addition, about 3% of mtDNAs from eastern Slovakia encompass Roma-specific lineages. By means of complete mtDNA sequencing we demonstrate here that the Roma-specific M-lineages observed in gene pools of different Slavonic populations (Slovaks, Poles and Russians), belong to Indian-specific haplogroups M5a1 and M35. Moreover, we show that haplogroup J lineages found in gene pools of the Roma and some Slavonic populations (Czechs and Slovaks) belong to new subhaplogroup J1a, which is defined by coding region mutation at position 8460.     

The Y-chromosomal Heritage of the Azores Islands Population

The Azores, a Portuguese archipelago located in the north Atlantic Ocean, had no native population when the Portuguese first arrived in the 15th century. The islands were populated mainly by the Portuguese, but Jews, Moorish prisoners, African slaves, Flemish, French and Spaniards also contributed to the initial settlement. To understand the paternal origins and diversity of the extant Azorean population, we typed genomic DNA samples from 172 individuals using a combination of 10 Y‐biallelic markers (YAP, SRY‐1532, SRY‐2627, 92R7, M9, sY81, Tat, SRY‐8299, 12f2 and LLY22g) and the following Y‐chromosomal STR systems: DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393 and DYS385. We identified nine different haplogroups, most of which are frequent in Europe. Haplogroup J* is the second most frequent in the Azores (13.4%), but it is modestly represented in mainland Portugal (6.8%). The other non‐European haplogroups, N3 and E3a, which are prevalent in Asia and sub‐Saharan Africa, respectively, have been found in the Azores (0.6% and 1.2%, respectively) but not in mainland Portugal. Microsatellite data indicate that the mean gene diversity (D) value for all the loci analysed in our sample set is 0.590, while haplotype diversity is 0.9994. Taken together, our analysis suggests that the current paternal pool of the Azorean population is, to a great extent, of Portuguese descent with significant contributions from people with other genetic backgrounds.     

Mitochondrial DNA Sequence Diversity in a Sedentary Population from Egypt

The mitochondrial DNA (mtDNA) diversity of 58 individuals from Upper Egypt, more than half (34 individuals) from Gurna, whose population has an ancient cultural history, were studied by sequencing the control‐region and screening diagnostic RFLP markers. This sedentary population presented similarities to the Ethiopian population by the L1 and L2 macrohaplogroup frequency (20.6%), by the West Eurasian component (defined by haplogroups H to K and T to X) and particularly by a high frequency (17.6%) of haplogroup M1. We statistically and phylogenetically analysed and compared the Gurna population with other Egyptian, Near East and sub‐Saharan Africa populations; AMOVA and Minimum Spanning Network analysis showed that the Gurna population was not isolated from neighbouring populations. Our results suggest that the Gurna population has conserved the trace of an ancestral genetic structure from an ancestral East African population, characterized by a high M1 haplogroup frequency. The current structure of the Egyptian population may be the result of further influence of neighbouring populations on this ancestral population.     

Migration Waves to the Baltic Sea Region

In this study, the population history of the Baltic Sea region, known to be affected by a variety of migrations and genetic barriers, was analyzed using both mitochondrial DNA and Y‐chromosomal data. Over 1200 samples from Finland, Sweden, Karelia, Estonia, Setoland, Latvia and Lithuania were genotyped for 18 Y‐chromosomal biallelic polymorphisms and 9 STRs, in addition to analyzing 17 coding region polymorphisms and the HVS1 region from the mtDNA. It was shown that the populations surrounding the Baltic Sea are genetically similar, which suggests that it has been an important route not only for cultural transmission but also for population migration. However, many of the migrations affecting the area from Central Europe, the Volga‐Ural region and from Slavic populations have had a quantitatively different impact on the populations, and, furthermore, the effects of genetic drift have increased the differences between populations especially in the north. The possible explanations for the high frequencies of several haplogroups with an origin in the Iberian refugia (H1, U5b, I1a) are also discussed.     

Genetic diversity in the Iberian Peninsula determined from mitochondrial sequence analysis

We have analysed 302 bp of the first hypervariable region of the mitochondrial D-loop in 271 individuals from different regions of the Iberian Peninsula and 85 individuals from Algeria. The Basque population is significantly different from neighbouring populations in terms of overall levels of diversity. This is because the majority of sequences in the Basques are restricted to the lineage group defined by the CRS (Cambridge Reference Sequence) and its derivatives although, like other Iberian populations, they showed a unimodal distribution of pairwise sequence differences. The timing of divergence of populations within Iberia points to a shared ancestry of all populations in the Upper Palaeolithic. Further genetic subdivision is apparent in Catalonia and Andalusia, with increased genetic diversity in the latter. Lineage diversity comparisons of Iberian populations with European (Tuscan) and North African (Algerian) populations shows the Iberian Peninsula to be more similar to other European populations, although a small number of Iberian lineages can be traced to North Africa.     

Prehistoric and historic traces in the mtDNA of Mozambique: insights into the Bantu expansions and the slave trade

A sample of mitochondrial DNA (mtDNA) from the southeastern African population of Mozambique has been shown to have affinities with populations both to its north and south. From the north came sequences that may have been involved in the Bantu expansion (from western, through eastern, to southern Africa), such as members of haplogroups L3b, L3e1a and a subset of L1a. The dating of the major component of Mozambican mtDNAs, the subset L2a of haplogroup L2, displayed an age range compatible with the Bantu expansion. The southern influence was traced by the presence of sequence types from haplogroup L1d, a probable relict of Khoisan-speaking populations that inhabited the region prior to their displacement by the Bantu-speaking incomers. Within historical times, the forced displacement of Mozambicans as part of the slave trade, mainly documented as being to the Americas, generated a differential input of eastern African sequences into the mtDNA pools of the Americas and of Europe, as testified to by the greater number of sequence matches between Mozambique and the Americas, compared to those between Mozambique and Europe.     

Genetic origins in a South American clefting population

It has been proposed that susceptibility to clefting in South America is related to Amerindian ancestry, where clefting is present at a higher frequency than in the other admixed populations (Caucasian and African) that make up the diverse racial mix of current South Americans. To clarify the genetic origins and establish a method for genetic mapping, mitochondrial DNA variation and Y-chromosome markers were studied in a South American population affected with clefting. Two-hundred and seventeen subjects and matched controls were selected through the Latin-American Collaborative Study of Congenital Malformations (ECLAMC). The case group showed a higher frequency of Native American haplogroups and a lower frequency of African haplogroups (p < 0.00001). In addition, the case group showed a much higher frequency of the specific native American haplogroup D than the control group (p < 0.00001). For the Y-chromosome markers, the case group showed a lower frequency of the African-specific marker, YAP (p = 0.002), and a higher frequency of the Native American-specific marker, DYS199 (p < 0.00001). Even though differences were found in the frequencies of the markers studied, the contribution of each founder population was similar for both groups. Results suggest a strong Native American maternal contribution and a strong Caucasian (Spanish and Portuguese) paternal contribution to the population studied. The implications of this finding include the possibility of using admixture mapping approaches to this population.     

Isolation and prominent aboriginal maternal legacy in the present-day population of La Gomera (Canary Islands)

The present-day population structure of La Gomera is outstanding in its high aboriginal heritage, the greatest in the Canary Islands. This was earlier confirmed by both mitochondrial DNA and autosomal analyses, although genetic drift due to the fifteenth century European colonization could not be excluded as the main factor responsible. The present mtDNA study of aboriginal remains and extant samples from the six municipal districts of the island indeed demonstrates that the pre-Hispanic colonization of La Gomera by North African people involved a strong founder event, shown by the high frequency of the indigenous Canarian U6b1a lineage in the aboriginal samples (65%). This value is even greater than that observed in the extant population (44%), which in turn is the highest of all the seven Canary Islands. In contrast to previous results obtained for the aboriginal populations of Tenerife and La Palma, haplogroups related to secondary waves of migration were not detected in La Gomera aborigines, indicating that isolation also had an important role in shaping the current population. The rugged relief of La Gomera divided into several distinct valleys probably promoted subsequent aboriginal intra-insular differentiation that has continued after the European colonization, as seen in the present-day population structure observed on the island.     

Seventy‐three nuclear DNA polymorphisms in a Spanish population and a comparison with ten other populations

An anthropologically well‐defined Spanish sample from La Alpujarra (SE Spain) was analyzed for 73 nuclear DNA polymorphisms. The population was chosen on the basis of available information on its history and demographic characteristics making it suitable for comparisons with data from North African populations. The Moslem invasion in this area was longer than anywhere in the Iberian Peninsula (more than nine centuries). The markers analyzed have been studied previously in 10 human populations from different continents. The Alpujarrenian population was checked for these markers and it is the one with the highest number of chromosomes analyzed. Two new alleles were sized and heterozygosity levels were very similar to other European populations. Genetic distances closely matched geographical relationships both with neighbor joining tree and principal component analysis. Allele distributions revealed specific associations with some populations. This work reveals the importance of these markers for evolutionary studies of human populations. Am. J. Hum. Biol. 13:212–219, 2001. © 2001 Wiley‐Liss, Inc.     

Geographical Structure of the Y-chromosomal Genetic Landscape of the Levant: A coastal-inland contrast

We have examined the male-specific phylogeography of the Levant and its surroundings by analyzing Y-chromosomal haplogroup distributions using 5874 samples (885 new) from 23 countries. The diversity within some of these haplogroups was also examined. The Levantine populations showed clustering in SNP and STR analyses when considered against a broad Middle-East and North African background. However, we also found a coastal-inland, east-west pattern of diversity and frequency distribution in several haplogroups within the small region of the Levant. Since estimates of effective population size are similar in the two regions, this strong pattern is likely to have arisen mainly from differential migrations, with different lineages introduced from the east and west.     

Genetic features of ancient West Siberian people of the Middle Ages, revealed by mitochondrial DNA haplogroup analysis

In order to investigate the genetic features of ancient West Siberian people of the Middle Ages, we studied ancient DNA from bone remains excavated from two archeological sites in West Siberia: Saigatinsky 6 (eighth to eleventh centuries) and Zeleny Yar (thirteenth century). Polymerase chain reaction amplification and nucleotide sequencing of mitochondrial DNA (mtDNA) succeeded for 9 of 67 specimens examined, and the sequences were assigned to mtDNA haplogroups B4, C4, G2, H and U. This distribution pattern of mtDNA haplogroups in medieval West Siberian people was similar to those previously reported in modern populations living in West Siberia, such as the Mansi, Ket and Nganasan. Exact tests of population differentiation showed no significant differences between the medieval people and modern populations in West Siberia. The findings suggest that some medieval West Siberian people analyzed in the present study are included in direct ancestral lineages of modern populations native to West Siberia.     

The African contribution to the present‐day population of the Azores Islands (Portugal): Analysis of the Y chromosome haplogroup E

Among the settlers that, from 1432 onwards, arrived to the Azores Islands were individuals of North and sub‐Saharan African origin. A previous study of markers of the Y chromosome revealed that haplogroup E is the second more frequent in the Azores (13%). Since this haplogroup is heterogeneous and may contain subtypes of African or non‐African origin, we analyzed an extended sample of 319 Azoreans, originating from the three groups of islands (Eastern, Central, and Western), to evaluate the African contribution to the present‐day population of the Azores. Samples belonging to the E clade were distributed into six haplogroups, from which the most frequent was E3b1a, representing 47.2% of the E chromosomes (6.3% of the total sample). The sub‐Saharan haplogroup E3a was found in 7.1% of E chromosomes (0.9% of the total), corresponding to the highest frequency reported so far in a Portuguese population. No significant differences were detected in the haplogroup distribution among groups of islands, as well as between Azores and most of other European populations compared. The present‐day representation of sub‐Saharan lineages in Azores, although reduced, is higher than in other Portuguese populations, where the demographic representation of sub‐Saharan slaves is reported as similar. Am. J. Hum. Biol., 2007. © 2007 Wiley‐Liss, Inc.     

Arboviruses in the Iberian Peninsula

The information concerning the presence and activity of arboviruses in the Iberian Peninsula is very scanty. In Portugal serological studies have been done with sera from animals, wild birds and human population. The results have shown that some arboviruses have been active in some areas of the territory. West Nile (WN) virus was isolated from mosquitoes and Dhori and Thogoto viruses have been isolated from ticks. In Spain, in spite of the large territory, it's geographical contiguity to Africa and the existence of different kinds of climates and ecologic conditions, the information is reduced to some surveys done in some restricted regions of the country. In both countries African swine fever was frequent and recently African horsesickness has been introduced to Southern Spain. A straight liaison and cooperation among virology laboratories of both countries and also Morocco should be emphasized in order to establish epidemiological surveillance in Southern Europe.