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Marı´a Jose´ Casas,1* Erika Hagelberg,1 Rosa Fregel,2 Jose´ M. Larruga,2 and Ana ... - page 7 / 13

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IMPACT OF AFRICAN MEDIEVAL MIGRATIONS IN SPAIN

545

Those sequences from Medieval and present popula- tion of Priego not found in NW Africa or Southern Iberia

were searched in other HVRI mtDNA data bases from large geographical areas (Table 2, Appendix), considering the positions between 16065 and 16365.

Divergence time estimations, based on control region mtDNA, were calculated as the mean divergence q

(Morral et al., 1994) from inferred ancestral sequence types and converted into time by assuming that one transition within the nucleotide positions 16090–16365 corresponds to 20,180 years (Foster et al., 1996).

TABLE 3. Linearized FST. between the medieval and present populations of Priego de Cordoba, South Iberian

Peninsula, and Northwest Africa

MP PP SIP

MP

PP 0.00258

SIP 0.00150

0.00121

NWA

    • 0.00361

      *

    • 0.00476

      **

    • 0.00287

      ***

MP indicates medieval Priego de Cordoba; PP, present popula- tion Priego de Cordoba; SIP, South Iberian Peninsula; NWA, Northwest Africa. *P < 0.05; **P < 0.01; ***P < 0.001.

RESULTS

From the 71 medieval samples available, 46 were ana- lyzed in Oslo and 35 in La Laguna. Ten of them were replicated in both the laboratories. Four samples failed in the extraction process. Five more were also discarded for being too incomplete as to be ascribed to haplogroups and, in Oslo, two samples were discarded for including the haplotype of the person handling the samples. The four duplicates in La Laguna gave identical HVRI sequences. Nine of the ten sequences replicated in both the laboratories were consistent. As the tenth corre- sponded to one of the two samples that, in Oslo, gave the sequence of the operator, the sequence from this duplicate processed in La Laguna was included in the study. Therefore the final sample size of medieval Priego was 61, giving an extraction efficiency of 93%, and a final efficiency of 85.9%.

To test powdering versus crushing and previous EDTA decalcification versus no EDTA decalcification, four sam- ple replications were carried out in La Laguna. Although we could not directly quantify the DNA extraction yield, powdering and no previous decalcification of the samples resulted in at least a twofold higher PCR amplification efficiency when compared with crushing and washing with EDTA solution before DNA extraction.

Seven haplotypes were found in both medieval and present day Priego samples but are absent in the refer- ence European and North African database. They account for 17% and 11% of the lineages respectively. Twelve haplotypes are present in both medieval and cur- rent Priego samples, which represent 29% for the medie- val sample and 19% for the present population. However, none of these haplotypes was exclusively shared between both samples. Haplotypes shared with South Iberia and/ or NW Africa and those absent in these areas but found in other regions are indicated in Table 2. Although the majority of the lineages of medieval (33; 80%) and pres- ent day (58; 89%) Priego samples are of Eurasian origin, the African contribution is higher in the historic sample (8; 20%) than in the current population (7; 11%).

FST distances based on haplotype frequencies (Table 3) show NW Africa as the only area significantly different from the others. The closest sample to NW Africa is me- dieval Priego. Congruently, in Iberia the largest distance are those where MP participate.

Haplogroup frequency comparisons

A mean of two PCR amplifications, for each fragment, were carried out in Oslo. Usually, only one PCR amplifi- cation was enough in La Laguna except for fragments 4 and 6 (Maca-Meyer et al., 2005) for which, in some indi- viduals, the amplification procedure had to be repeated up to three times.

PCR contamination was sporadic and could be over- come by cleaning the extraction laboratory and leaving it inoperative for at least 48 h and using new aliquots of PCR reagents and buffers in the repeated reactions. Contamination of the extraction blank was detected only with contamination of the PCR negative controls, and was also always successfully overcome upon repeating the amplifications with new aliquots.

Haplotype classification and distribution

The number of different haplotypes found in medieval (MP) and current (PP) population of Priego de Cordoba (Table 2) was 41 and 65 respectively. Gene diversities are practically identical in both the historical (0.95 6 0.02) and present day (0.96 6 0.01) samples, and not significantly different from South Iberia (0.96 6 0.01) or NW Africa (0.98 6 0.00). These results confirm that the sampling procedure followed to obtain the medieval remains was adequate to avoid sampling repetitions.

Haplogroup frequencies in the historic and current Priego samples and in geographically related areas are listed in Table 4 and graphically represented in Figure 1.

The characteristic North African U6 haplogroup (Rando et al., 1998; Maca-Meyer et al., 2003) was not detected in MP, and only once in the PP sample. How- ever, the percentage of African haplogroups in MP (15%) is significantly (P < 0.05) higher than in the present day south Iberia (6%) and half of that found for NW Africa (32%). Furthermore there is a significant difference (Fisher test, P ¼ 0.02) in the proportion of sub-Saharan Africa lineages between the historical and present day Priego samples. This could be due to the Castilian repo- pulation after the Christian reconquest of this region.

In relation to the Eurasian haplogroup distribution, it is worth mentioning that frequencies for T and J hap- logroups are higher in MP than in PP, whereas the K haplogroup is more frequent in PP than in MP, with the former being similar to the South Iberian (SIP) sample (Table 4). Although there is a rare haplotype match (189 362) between Priego samples, in general, haplogroup fre- quencies of the PP sample are more in accordance with the current SIP distribution than with the MP sample (Table 4). The increased gene flow among areas in mod- ern times could be the main cause of this difference. However, differences in the Eurasian haplogroup fre- quency distribution between both Priego samples are not statistically significant (P ¼ 0.08).

American Journal of Physical Anthropology—DOI 10.1002/ajpa

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