Rosa Fregel
My research interest has been centered on the use of paleogenetic techniques to deciphering the history of past populations and understanding how migration patters have shaped ancient and modern populations’ structure. Most of my projects have been related to European colonialism and how it impacted global demography, both on the Atlantic (Canary Islands) and the Indian Oceans (Mauritius).
My PhD project consisted of assessment of the temporal evolution of the human inhabitants of the Canary Islands using aDNA techniques. During the 13th century, Portuguese sailors discovered several archipelagos in the Atlantic Ocean, among which the Canary Islands was the only one inhabited. The European explorers were surprised to discover they did not have enough seafaring skills to have reached the islands from Africa. The Spanish kingdom of Castile conquered the islands during the 15th century, leading to the complete mixing of the indigenous people with the European colonizers. The results of my PhD project helped confirming the origin of the indigenous people of the Canary Islands based on uniparental and autosomal data, and provided a better understanding on the effects that the conquest and posterior European colonization had on the aboriginal people.
After finishing my PhD, I worked in a multidisciplinary team, together with La Universidad de Las Palmas de Gran Canaria and the Institute of Legal Medicine of Las Palmas (Spain), in a national project funded to allow the genetic identification of human remains in mass grave from the political repression that followed the Spanish Civil War (1936 - 1939). Using my experience with PCR amplification of severely degraded DNA, we were able to identify seven human remains excavated in the island of Gran Canaria.
In 2014, I moved to Stanford University (US) to gain expertise on whole genome techniques, such as next-generation sequencing (NGS) and genome-wide SNP analysis. I was also interested on applying and improving the new DNA capture technology developed at Stanford for enriching degraded ancient samples on endogenous DNA. At Stanford, in collaboration with the University of California at Santa Cruz (US), University of Rabat (Morocco) and University of La Laguna (Spain), we performed the first paleogenetic comparison of Neolithic populations at both sides of the Gibraltar Strait, including archaeological sites from both South Iberia and North Africa, to test the existence of prehistorical contact between the two areas.
Now, as an Assistant Professor at University of La Laguna , I'm leading two different projects:
a) In collaboration with the University of Las Palmas de Gran Canaria, and several local museums of the Canaries, we are performing the first aDNA analysis of ancient populations of the whole Canary Islands at a genomic level, to use nuclear admixture patterns for inferring the indigenous colonization process.
b) In collaboration with the Department of Anthropology at Stanford University, and the University of Mauritius (Mauritius), we are performing the first NGS and whole-genome SNP analysis of historical and current populations of Mauritius to obtain novel data on labor diaspora across the Indian Ocean during colonial times.
Phone: +1 650 440 8126
Address: Bustamante Lab
School of Medicine
Stanford University
450 Serra Mall 94305
California
United States
My PhD project consisted of assessment of the temporal evolution of the human inhabitants of the Canary Islands using aDNA techniques. During the 13th century, Portuguese sailors discovered several archipelagos in the Atlantic Ocean, among which the Canary Islands was the only one inhabited. The European explorers were surprised to discover they did not have enough seafaring skills to have reached the islands from Africa. The Spanish kingdom of Castile conquered the islands during the 15th century, leading to the complete mixing of the indigenous people with the European colonizers. The results of my PhD project helped confirming the origin of the indigenous people of the Canary Islands based on uniparental and autosomal data, and provided a better understanding on the effects that the conquest and posterior European colonization had on the aboriginal people.
After finishing my PhD, I worked in a multidisciplinary team, together with La Universidad de Las Palmas de Gran Canaria and the Institute of Legal Medicine of Las Palmas (Spain), in a national project funded to allow the genetic identification of human remains in mass grave from the political repression that followed the Spanish Civil War (1936 - 1939). Using my experience with PCR amplification of severely degraded DNA, we were able to identify seven human remains excavated in the island of Gran Canaria.
In 2014, I moved to Stanford University (US) to gain expertise on whole genome techniques, such as next-generation sequencing (NGS) and genome-wide SNP analysis. I was also interested on applying and improving the new DNA capture technology developed at Stanford for enriching degraded ancient samples on endogenous DNA. At Stanford, in collaboration with the University of California at Santa Cruz (US), University of Rabat (Morocco) and University of La Laguna (Spain), we performed the first paleogenetic comparison of Neolithic populations at both sides of the Gibraltar Strait, including archaeological sites from both South Iberia and North Africa, to test the existence of prehistorical contact between the two areas.
Now, as an Assistant Professor at University of La Laguna , I'm leading two different projects:
a) In collaboration with the University of Las Palmas de Gran Canaria, and several local museums of the Canaries, we are performing the first aDNA analysis of ancient populations of the whole Canary Islands at a genomic level, to use nuclear admixture patterns for inferring the indigenous colonization process.
b) In collaboration with the Department of Anthropology at Stanford University, and the University of Mauritius (Mauritius), we are performing the first NGS and whole-genome SNP analysis of historical and current populations of Mauritius to obtain novel data on labor diaspora across the Indian Ocean during colonial times.
Phone: +1 650 440 8126
Address: Bustamante Lab
School of Medicine
Stanford University
450 Serra Mall 94305
California
United States
less
InterestsView All (19)
Uploads
Papers by Rosa Fregel
In this study, we design: 1) a refined mtDNA cladistic nomenclature from a phylogenetic tree based on complete sequences, classifying dog maternal lineages into haplogroups defined by specific diagnostic mutations. 2) a coding region SNP analysis that allows a more accurate classification into haplogroups when combined with D-loop sequencing, thus improving the phylogenetic information obtained in dog mitochondrial DNA studies.
Results: Using 230 complete sequences we have refined the U6 phylogeny, and improved the phylogeographic information by the analysis of 761 partial sequences. This approach provides chronological limits for its arrival to Africa, followed by its spreads there according to climatic fluctuations, and its secondary prehistoric and historic migrations out of Africa colonizing Europe, the Canary Islands and the American Continent.
Conclusions: The U6 expansions and contractions inside Africa faithfully reflect the climatic fluctuations that occurred in this Continent affecting also the Canary Islands. Mediterranean contacts drove these lineages to Europe, at least since the Neolithic. In turn, the European colonization brought different U6 lineages throughout the American Continent leaving the specific sign of the colonizers origin.
Methods: The control region of mitochondrial DNA and haplogroup diagnostic positions were analyzed in 575 subjects and Y-chromosome markers were typed in 260 unrelated males. Moreover, previously published data were compiled
and used in the analyses.
Results: The level of genetic structure deduced from uniparental markers for the Iberian Peninsula was weak, with stronger Atlantic versus Mediterranean than North to South differentiation and larger diversities in the South. In general, mitochondrial DNA haplogroups had mainly Paleolithic and Mesolithic coalescences in Europe, although some of them, ruling out drift effects, seem to have younger implantation in Central Europe and the Atlantic areas than in the Mediterranean (I, J, J2a, T1, and W) while others as N1 and X could have reached the Iberian Peninsula at the Neolithic transition. On the other hand, younger coalescence ages are being proposed for the arriving or spread of the bulk of Y-chromosome lineages in Europe.
Conclusions: The major haplotypic affinities found for all the Iberian Peninsula regions were always with North Africa and the Atlantic Islands. These results draw an Atlantic network that clearly resembles those of the Megalithic Copper and Bronze cultures at this part of Europe."
Continent, studies of mitochondrial DNA (mtDNA) and Y-chromosome genealogical markers provide evidence that the
North African gene pool has been shaped by the back-migration of several Eurasian lineages in Paleolithic and Neolithic
times. More recent influences from sub-Saharan Africa and Mediterranean Europe are also evident. The presence of East-
West and North-South haplogroup frequency gradients strongly reinforces the genetic complexity of this region. However,
this genetic scenario is beset with a notable gap, which is the lack of consistent information for Algeria, the largest country
in the Maghreb. To fill this gap, we analyzed a sample of 240 unrelated subjects from a northwest Algeria cosmopolitan
population using mtDNA sequences and Y-chromosome biallelic polymorphisms, focusing on the fine dissection of
haplogroups E and R, which are the most prevalent in North Africa and Europe respectively. The Eurasian component in
Algeria reached 80% for mtDNA and 90% for Y-chromosome. However, within them, the North African genetic component
for mtDNA (U6 and M1; 20%) is significantly smaller than the paternal (E-M81 and E-V65; 70%). The unexpected presence of
the European-derived Y-chromosome lineages R-M412, R-S116, R-U152 and R-M529 in Algeria and the rest of the Maghreb
could be the counterparts of the mtDNA H1, H3 and V subgroups, pointing to direct maritime contacts between the
European and North African sides of the western Mediterranean. Female influx of sub-Saharan Africans into Algeria (20%) is
also significantly greater than the male (10%). In spite of these sexual asymmetries, the Algerian uniparental profiles
faithfully correlate between each other and with the geography.
In this study, we design: 1) a refined mtDNA cladistic nomenclature from a phylogenetic tree based on complete sequences, classifying dog maternal lineages into haplogroups defined by specific diagnostic mutations. 2) a coding region SNP analysis that allows a more accurate classification into haplogroups when combined with D-loop sequencing, thus improving the phylogenetic information obtained in dog mitochondrial DNA studies.
Results: Using 230 complete sequences we have refined the U6 phylogeny, and improved the phylogeographic information by the analysis of 761 partial sequences. This approach provides chronological limits for its arrival to Africa, followed by its spreads there according to climatic fluctuations, and its secondary prehistoric and historic migrations out of Africa colonizing Europe, the Canary Islands and the American Continent.
Conclusions: The U6 expansions and contractions inside Africa faithfully reflect the climatic fluctuations that occurred in this Continent affecting also the Canary Islands. Mediterranean contacts drove these lineages to Europe, at least since the Neolithic. In turn, the European colonization brought different U6 lineages throughout the American Continent leaving the specific sign of the colonizers origin.
Methods: The control region of mitochondrial DNA and haplogroup diagnostic positions were analyzed in 575 subjects and Y-chromosome markers were typed in 260 unrelated males. Moreover, previously published data were compiled
and used in the analyses.
Results: The level of genetic structure deduced from uniparental markers for the Iberian Peninsula was weak, with stronger Atlantic versus Mediterranean than North to South differentiation and larger diversities in the South. In general, mitochondrial DNA haplogroups had mainly Paleolithic and Mesolithic coalescences in Europe, although some of them, ruling out drift effects, seem to have younger implantation in Central Europe and the Atlantic areas than in the Mediterranean (I, J, J2a, T1, and W) while others as N1 and X could have reached the Iberian Peninsula at the Neolithic transition. On the other hand, younger coalescence ages are being proposed for the arriving or spread of the bulk of Y-chromosome lineages in Europe.
Conclusions: The major haplotypic affinities found for all the Iberian Peninsula regions were always with North Africa and the Atlantic Islands. These results draw an Atlantic network that clearly resembles those of the Megalithic Copper and Bronze cultures at this part of Europe."
Continent, studies of mitochondrial DNA (mtDNA) and Y-chromosome genealogical markers provide evidence that the
North African gene pool has been shaped by the back-migration of several Eurasian lineages in Paleolithic and Neolithic
times. More recent influences from sub-Saharan Africa and Mediterranean Europe are also evident. The presence of East-
West and North-South haplogroup frequency gradients strongly reinforces the genetic complexity of this region. However,
this genetic scenario is beset with a notable gap, which is the lack of consistent information for Algeria, the largest country
in the Maghreb. To fill this gap, we analyzed a sample of 240 unrelated subjects from a northwest Algeria cosmopolitan
population using mtDNA sequences and Y-chromosome biallelic polymorphisms, focusing on the fine dissection of
haplogroups E and R, which are the most prevalent in North Africa and Europe respectively. The Eurasian component in
Algeria reached 80% for mtDNA and 90% for Y-chromosome. However, within them, the North African genetic component
for mtDNA (U6 and M1; 20%) is significantly smaller than the paternal (E-M81 and E-V65; 70%). The unexpected presence of
the European-derived Y-chromosome lineages R-M412, R-S116, R-U152 and R-M529 in Algeria and the rest of the Maghreb
could be the counterparts of the mtDNA H1, H3 and V subgroups, pointing to direct maritime contacts between the
European and North African sides of the western Mediterranean. Female influx of sub-Saharan Africans into Algeria (20%) is
also significantly greater than the male (10%). In spite of these sexual asymmetries, the Algerian uniparental profiles
faithfully correlate between each other and with the geography.
En general, las frecuencias observadas en la población actual de Canarias son similares a las de la Península Ibérica para todos los marcadores autosómicos, pero con cierta influencia norteafricana, explicada por ejemplo por la presencia del haplotipo 110(-) del marcador CD4/Alu o la alta frecuencia de alelo cDe del grupo Rh.
Igualmente, el uso de estimadores de mezcla señala a una mayor aportación de la Península Ibérica (en torno al 70-89%), con unos valores intermedios entre los obtenidos mediante el uso de ambos marcadores uniparentales, ADNmt (≈ 67%) y cromosoma Y (≈ 90%).
Por otro lado, el estudio en poblaciones actuales de marcadores autosómicos también ha aportado cierta información sobre el poblamiento de Canarias. Concretamente, los haplotipos CD4/Alu y el locus ABO han mostrado una correlación negativa entre la distancia de las islas al continente africano, y la heterocigocidad insular y la frecuencia del alelo B101, respectivamente. Este resultado, podría deberse a una colonización aborigen dominante de este a oeste desde África.
Finalmente, al determinar el marcador autosómico ABO en poblaciones aborígenes se confirma el origen norteafricano de la población prehispánica. Por otro lado, la muestra histórica del S.XVIII, se sitúa en una posición intermedia entre la población aborigen y la actual, evidenciando el fuerte impacto de la conquista y posterior colonización de la islas sobre la población indígena.
There are numerous pieces of evidence that point towards the interpretation that the individuals could have been part of a slave burial ground. These evidences are given by the immediate surrounds directly relevant to the cemetery use, and also by the burial practices, which have not been recorded yet in Gran Canaria.
In order to determine the genetic origins of the human remains, mitochondrial DNA determinations were carried out from each individual skeleton.
The frequencies of the mtDNA haplogroups observed are compared to those already reported in the literature from a) other ancient populations from the Basque Country (the prehistoric sites of Longar, Pico Ramos and SJAPL), b) the historical site of Aldaieta and c) those corresponding to extant European populations compiled in different databases.
We observed that the variability of the mtDNA haplogroupd of the historical population of Aldaieta falls within the range of the present-day populations of the European Atlantic fringe, whereas the prehistorical populations of the Basque Country differentiate from the rest of the samples. Consequently, we suggst that between 6,000-1,500 YBP approximately, a certain amount of gene flow amongst the western European populations that homogenised their mtDNA lineages, may have taken place.