Publications by authors named "Silvia Ghirotto"

38 Publications

Y-chromosome variability and genetic history of Commons from Northern Italy.

Am J Phys Anthropol 2021 May 10. Epub 2021 May 10.

Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy.

Objectives: Genetic drift and admixture are driving forces in human evolution, but their concerted impact to population evolution in historical times and at a micro-geographic scale is poorly assessed. In this study we test a demographic model encompassing both admixture and drift to the case of social-cultural isolates such as the so-called "Commons."

Materials And Methods: Commons are peculiar institutions of medieval origins whose key feature is the tight relationship between population and territory, mediated by the collective property of shared resources. Here, we analyze the Y-chromosomal genetic structure of four Commons (for a total of 366 samples) from the Central and Eastern Padana plain in Northern Italy.

Results: Our results reveal that all these groups exhibit patterns of significant diversity reduction, peripheral/outlier position within the Italian/European genetic space and high frequency of Common-specific haplogroups. By explicitly testing different drift-admixture models, we show that a drift-only model is more probable for Central Padana Commons, while additional admixture (~20%) from external population around the same time of their foundation cannot be excluded for the Eastern ones.

Discussion: Building on these results, we suggest central Middle Ages as the most probable age of foundation for three of the considered Commons, the remaining one pointing to late antiquity. We conclude that an admixture-drift model is particularly useful for interpreting the genetic structure and recent demographic history of small-scale populations in which social-cultural features play a significant role.
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http://dx.doi.org/10.1002/ajpa.24302DOI Listing
May 2021

A Revised Model of Anatomically Modern Human Expansions Out of Africa through a Machine Learning Approximate Bayesian Computation Approach.

Genes (Basel) 2020 12 16;11(12). Epub 2020 Dec 16.

Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.

There is a wide consensus in considering Africa as the birthplace of anatomically modern humans (AMH), but the dispersal pattern and the main routes followed by our ancestors to colonize the world are still matters of debate. It is still an open question whether AMH left Africa through a single process, dispersing almost simultaneously over Asia and Europe, or in two main waves, first through the Arab Peninsula into southern Asia and Australo-Melanesia, and later through a northern route crossing the Levant. The development of new methodologies for inferring population history and the availability of worldwide high-coverage whole-genome sequences did not resolve this debate. In this work, we test the two main out-of-Africa hypotheses through an Approximate Bayesian Computation approach, based on the Random-Forest algorithm. We evaluated the ability of the method to discriminate between the alternative models of AMH out-of-Africa, using simulated data. Once assessed that the models are distinguishable, we compared simulated data with real genomic variation, from modern and archaic populations. This analysis showed that a model of multiple dispersals is four-fold as likely as the alternative single-dispersal model. According to our estimates, the two dispersal processes may be placed, respectively, around 74,000 and around 46,000 years ago.
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http://dx.doi.org/10.3390/genes11121510DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766041PMC
December 2020

Distinguishing among complex evolutionary models using unphased whole-genome data through random forest approximate Bayesian computation.

Mol Ecol Resour 2020 Sep 30. Epub 2020 Sep 30.

Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.

Inferring past demographic histories is crucial in population genetics, and the amount of complete genomes now available should in principle facilitate this inference. In practice, however, the available inferential methods suffer from severe limitations. Although hundreds complete genomes can be simultaneously analysed, complex demographic processes can easily exceed computational constraints, and the procedures to evaluate the reliability of the estimates contribute to increase the computational effort. Here we present an approximate Bayesian computation framework based on the random forest algorithm (ABC-RF), to infer complex past population processes using complete genomes. To this aim, we propose to summarize the data by the full genomic distribution of the four mutually exclusive categories of segregating sites (FDSS), a statistic fast to compute from unphased genome data and that does not require the ancestral state of alleles to be known. We constructed an efficient ABC pipeline and tested how accurately it allows one to recognize the true model among models of increasing complexity, using simulated data and taking into account different sampling strategies in terms of number of individuals analysed, number and size of the genetic loci considered. We also compared the FDSS with the unfolded and folded site frequency spectrum (SFS), and for these statistics we highlighted the experimental conditions maximizing the inferential power of the ABC-RF procedure. We finally analysed real data sets, testing models on the dispersal of anatomically modern humans out of Africa and exploring the evolutionary relationships of the three species of Orangutan inhabiting Borneo and Sumatra.
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http://dx.doi.org/10.1111/1755-0998.13263DOI Listing
September 2020

Contrasting Paternal and Maternal Genetic Histories of Thai and Lao Populations.

Mol Biol Evol 2019 07;36(7):1490-1506

Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

The human demographic history of Mainland Southeast Asia (MSEA) has not been well studied; in particular, there have been very few sequence-based studies of variation in the male-specific portions of the Y chromosome (MSY). Here, we report new MSY sequences of ∼2.3 mB from 914 males and combine these with previous data for a total of 928 MSY sequences belonging to 59 populations from Thailand and Laos who speak languages belonging to three major Mainland Southeast Asia families: Austroasiatic, Tai-Kadai, and Sino-Tibetan. Among the 92 MSY haplogroups, two main MSY lineages (O1b1a1a* [O-M95*] and O2a* [O-M324*]) contribute substantially to the paternal genetic makeup of Thailand and Laos. We also analyze complete mitochondrial DNA genome sequences published previously from the same groups and find contrasting pattern of male and female genetic variation and demographic expansions, especially for the hill tribes, Mon, and some major Thai groups. In particular, we detect an effect of postmarital residence pattern on genetic diversity in patrilocal versus matrilocal groups. Additionally, both male and female demographic expansions were observed during the early Mesolithic (∼10 ka), with two later major male-specific expansions during the Neolithic period (∼4-5 ka) and the Bronze/Iron Age (∼2.0-2.5 ka). These two later expansions are characteristic of the modern Austroasiatic and Tai-Kadai groups, respectively, consistent with recent ancient DNA studies. We simulate MSY data based on three demographic models (continuous migration, demic diffusion, and cultural diffusion) of major Thai groups and find different results from mitochondrial DNA simulations, supporting contrasting male and female genetic histories.
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http://dx.doi.org/10.1093/molbev/msz083DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6573475PMC
July 2019

A genetic perspective on Longobard-Era migrations.

Eur J Hum Genet 2019 04 16;27(4):647-656. Epub 2019 Jan 16.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, 44121, Ferrara, Italy.

From the first century AD, Europe has been interested by population movements, commonly known as Barbarian migrations. Among these processes, the one involving the Longobard culture interested a vast region, but its dynamics and demographic impact remains largely unknown. Here we report 87 new complete mitochondrial sequences coming from nine early-medieval cemeteries located along the area interested by the Longobard migration (Czech Republic, Hungary and Italy). From the same areas, we sampled necropoleis characterized by cultural markers associated with the Longobard culture (LC) and coeval burials where no such markers were found, or with a chronology slightly preceding the presumed arrival of the Longobards in that region (NLC). Population genetics analysis and demographic modeling highlighted a similarity between LC individuals, as reflected by the sharing of quite rare haplogroups and by the degree of genetic resemblance between Hungarian and Italian LC necropoleis estimated via a Bayesian approach, ABC. The demographic model receiving the strongest statistical support also postulates a contact between LC and NLC communities, thus indicating a complex dynamics of admixture in medieval Europe.
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http://dx.doi.org/10.1038/s41431-018-0319-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6460631PMC
April 2019

Understanding 6th-century barbarian social organization and migration through paleogenomics.

Nat Commun 2018 09 11;9(1):3547. Epub 2018 Sep 11.

Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11790, USA.

Despite centuries of research, much about the barbarian migrations that took place between the fourth and sixth centuries in Europe remains hotly debated. To better understand this key era that marks the dawn of modern European societies, we obtained ancient genomic DNA from 63 samples from two cemeteries (from Hungary and Northern Italy) that have been previously associated with the Longobards, a barbarian people that ruled large parts of Italy for over 200 years after invading from Pannonia in 568 CE. Our dense cemetery-based sampling revealed that each cemetery was primarily organized around one large pedigree, suggesting that biological relationships played an important role in these early medieval societies. Moreover, we identified genetic structure in each cemetery involving at least two groups with different ancestry that were very distinct in terms of their funerary customs. Finally, our data are consistent with the proposed long-distance migration from Pannonia to Northern Italy.
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http://dx.doi.org/10.1038/s41467-018-06024-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6134036PMC
September 2018

The female ancestor's tale: Long-term matrilineal continuity in a nonisolated region of Tuscany.

Am J Phys Anthropol 2018 11 6;167(3):497-506. Epub 2018 Sep 6.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, Ferrara, Italy.

Objectives: With the advent of ancient DNA analyses, it has been possible to disentangle the contribution of ancient populations to the genetic pool of the modern inhabitants of many regions. Reconstructing the maternal ancestry has often highlighted genetic continuity over several millennia, but almost always in isolated areas. Here we analyze North-western Tuscany, a region that was a corridor of exchanges between Central Italy and the Western Mediterranean coast.

Materials And Methods: We newly obtained mitochondrial HVRI sequences from 28 individuals, and after gathering published data, we collected genetic information for 119 individuals from the region. Those span five periods during the last 5,000 years: Prehistory, Etruscan age, Roman age, Renaissance, and Present-day. We used serial coalescent simulations in an approximate Bayesian computation framework to test for continuity between the mentioned groups.

Results: Our analyses always favor continuity over discontinuity for all groups considered, with the Etruscans being part of the genealogy. Moreover, the posterior distributions of the parameters support very small female effective population sizes.

Conclusions: The observed signals of long-term genetic continuity and isolation are in contrast with the history of the region, conquered several times (Etruscans, Romans, Lombards, and French). While the Etruscans appear as a local population, intermediate between the prehistoric and the other samples, we suggest that the other conquerors-arriving from far-had a consistent social or sex bias, hence only marginally affecting the maternal lineages. At the same time, our results show that long-term genealogical continuity is not necessarily linked to geographical isolation.
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http://dx.doi.org/10.1002/ajpa.23679DOI Listing
November 2018

New insights from Thailand into the maternal genetic history of Mainland Southeast Asia.

Eur J Hum Genet 2018 06 26;26(6):898-911. Epub 2018 Feb 26.

Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

Tai-Kadai (TK) is one of the major language families in Mainland Southeast Asia (MSEA), with a concentration in the area of Thailand and Laos. Our previous study of 1234 mtDNA genome sequences supported a demic diffusion scenario in the spread of TK languages from southern China to Laos as well as northern and northeastern Thailand. Here we add an additional 560 mtDNA genomes from 22 groups, with a focus on the TK-speaking central Thai people and the Sino-Tibetan speaking Karen. We find extensive diversity, including 62 haplogroups not reported previously from this region. Demic diffusion is still a preferable scenario for central Thais, emphasizing the expansion of TK people through MSEA, although there is also some support for gene flow between central Thai and native Austroasiatic speaking Mon and Khmer. We also tested competing models concerning the genetic relationships of groups from the major MSEA languages, and found support for an ancestral relationship of TK and Austronesian-speaking groups.
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http://dx.doi.org/10.1038/s41431-018-0113-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5974021PMC
June 2018

Genome diversity in the Neolithic Globular Amphorae culture and the spread of Indo-European languages.

Proc Biol Sci 2017 Nov;284(1867)

Department of Life Sciences and Biotechnology, University of Firenze, Firenze, Italy

It is unclear whether Indo-European languages in Europe spread from the Pontic steppes in the late Neolithic, or from Anatolia in the Early Neolithic. Under the former hypothesis, people of the Globular Amphorae culture (GAC) would be descended from Eastern ancestors, likely representing the Yamnaya culture. However, nuclear (six individuals typed for 597 573 SNPs) and mitochondrial (11 complete sequences) DNA from the GAC appear closer to those of earlier Neolithic groups than to the DNA of all other populations related to the Pontic steppe migration. Explicit comparisons of alternative demographic models via approximate Bayesian computation confirmed this pattern. These results are not in contrast to Late Neolithic gene flow from the Pontic steppes into Central Europe. However, they add nuance to this model, showing that the eastern affinities of the GAC in the archaeological record reflect cultural influences from other groups from the East, rather than the movement of people.
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http://dx.doi.org/10.1098/rspb.2017.1540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5719168PMC
November 2017

Survival and divergence in a small group: The extraordinary genomic history of the endangered Apennine brown bear stragglers.

Proc Natl Acad Sci U S A 2017 11 24;114(45):E9589-E9597. Epub 2017 Oct 24.

Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy;

About 100 km east of Rome, in the central Apennine Mountains, a critically endangered population of ∼50 brown bears live in complete isolation. Mating outside this population is prevented by several 100 km of bear-free territories. We exploited this natural experiment to better understand the gene and genomic consequences of surviving at extremely small population size. We found that brown bear populations in Europe lost connectivity since Neolithic times, when farming communities expanded and forest burning was used for land clearance. In central Italy, this resulted in a 40-fold population decline. The overall genomic impact of this decline included the complete loss of variation in the mitochondrial genome and along long stretches of the nuclear genome. Several private and deleterious amino acid changes were fixed by random drift; predicted effects include energy deficit, muscle weakness, anomalies in cranial and skeletal development, and reduced aggressiveness. Despite this extreme loss of diversity, Apennine bear genomes show nonrandom peaks of high variation, possibly maintained by balancing selection, at genomic regions significantly enriched for genes associated with immune and olfactory systems. Challenging the paradigm of increased extinction risk in small populations, we suggest that random fixation of deleterious alleles () can be an important driver of divergence in isolation, () can be tolerated when balancing selection prevents random loss of variation at important genes, and () is followed by or results directly in favorable behavioral changes.
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http://dx.doi.org/10.1073/pnas.1707279114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5692547PMC
November 2017

Reconstructing human population history from dental phenotypes.

Sci Rep 2017 10 2;7(1):12495. Epub 2017 Oct 2.

Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls University of Tübingen, Tübingen, Baden-Württemberg, 72070, Germany.

Dental phenotypic data are often used to reconstruct biological relatedness among past human groups. Teeth are an important data source because they are generally well preserved in the archaeological and fossil record, even when associated skeletal and DNA preservation is poor. Furthermore, tooth form is considered to be highly heritable and selectively neutral; thus, teeth are assumed to be an excellent proxy for neutral genetic data when none are available. However, to our knowledge, no study to date has systematically tested the assumption of genetic neutrality of dental morphological features on a global scale. Therefore, for the first time, this study quantifies the correlation of biological affinities between worldwide modern human populations, derived independently from dental phenotypes and neutral genetic markers. We show that population relationship measures based on dental morphology are significantly correlated with those based on neutral genetic data (on average r = 0.574, p < 0.001). This relatively strong correlation validates tooth form as a proxy for neutral genomic markers. Nonetheless, we suggest caution in reconstructions of population affinities based on dental data alone because only part of the dental morphological variation among populations can be explained in terms of neutral genetic differences.
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http://dx.doi.org/10.1038/s41598-017-12621-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5624867PMC
October 2017

Analysis of the R1b-DF27 haplogroup shows that a large fraction of Iberian Y-chromosome lineages originated recently in situ.

Sci Rep 2017 08 4;7(1):7341. Epub 2017 Aug 4.

Institut de Biologia Evolutiva (CSIC-UPF), Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.

Haplogroup R1b-M269 comprises most Western European Y chromosomes; of its main branches, R1b-DF27 is by far the least known, and it appears to be highly prevalent only in Iberia. We have genotyped 1072 R1b-DF27 chromosomes for six additional SNPs and 17 Y-STRs in population samples from Spain, Portugal and France in order to further characterize this lineage and, in particular, to ascertain the time and place where it originated, as well as its subsequent dynamics. We found that R1b-DF27 is present in frequencies ~40% in Iberian populations and up to 70% in Basques, but it drops quickly to 6-20% in France. Overall, the age of R1b-DF27 is estimated at ~4,200 years ago, at the transition between the Neolithic and the Bronze Age, when the Y chromosome landscape of W Europe was thoroughly remodeled. In spite of its high frequency in Basques, Y-STR internal diversity of R1b-DF27 is lower there, and results in more recent age estimates; NE Iberia is the most likely place of origin of DF27. Subhaplogroup frequencies within R1b-DF27 are geographically structured, and show domains that are reminiscent of the pre-Roman Celtic/Iberian division, or of the medieval Christian kingdoms.
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http://dx.doi.org/10.1038/s41598-017-07710-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544771PMC
August 2017

Y chromosomal evidence on the origin of northern Thai people.

PLoS One 2017 24;12(7):e0181935. Epub 2017 Jul 24.

Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand.

The Khon Mueang represent the major group of people present in today's northern Thailand. While linguistic and genetic data seem to support a shared ancestry between Khon Mueang and other Tai-Kadai speaking people, the possibility of an admixed origin with contribution from local Mon-Khmer population could not be ruled out. Previous studies conducted on northern Thai people did not provide a definitive answer and, in addition, have largely overlooked the distribution of paternal lineages in the area. In this work we aim to provide a comprehensive analysis of Y paternal lineages in northern Thailand and to explicitly model the origin of the Khon Mueang population. We obtained and analysed new Y chromosomal haplogroup data from more than 500 northern Thai individuals including Khon Mueang, Mon-Khmer and Tai-Kadai. We also explicitly simulated different demographic scenarios, developed to explain the Khon Mueang origin, employing an ABC simulation framework on both mitochondrial and Y microsatellites data. Our results highlighted a similar haplogroup composition of Khon Mueang and Tai-Kadai populations in northern Thailand, with shared high frequencies of haplogroups O-PK4, O-M117 and O-M111. Our ABC simulations also favoured a model in which the ancestors of modern Khon Mueang originated recently after a split from the other Tai-Kadai populations. Our different analyses concluded that the ancestors of Khon Mueang are likely to have originated from the same source of the other Tai-Kadai groups in southern China, with subsequent admixture events involving native Mon-Khmer speakers restricted to some specific populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0181935PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524406PMC
September 2017

Complete mitochondrial sequences from Mesolithic Sardinia.

Sci Rep 2017 03 3;7:42869. Epub 2017 Mar 3.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, 44121 Ferrara, Italy.

Little is known about the genetic prehistory of Sardinia because of the scarcity of pre-Neolithic human remains. From a genetic perspective, modern Sardinians are known as genetic outliers in Europe, showing unusually high levels of internal diversity and a close relationship to early European Neolithic farmers. However, how far this peculiar genetic structure extends and how it originated was to date impossible to test. Here we present the first and oldest complete mitochondrial sequences from Sardinia, dated back to 10,000 yBP. These two individuals, while confirming a Mesolithic occupation of the island, belong to rare mtDNA lineages, which have never been found before in Mesolithic samples and that are currently present at low frequencies not only in Sardinia, but in the whole Europe. Preliminary Approximate Bayesian Computations, restricted by biased reference samples for Mesolithic Sardinia (the two typed samples) and Neolithic Europe (limited to central and north European sequences), suggest that the first inhabitants of the island have had a small or negligible contribution to the present-day Sardinian population, which mainly derives its genetic diversity from continental migration into the island by Neolithic times.
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http://dx.doi.org/10.1038/srep42869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5335606PMC
March 2017

Complete mitochondrial genomes of Thai and Lao populations indicate an ancient origin of Austroasiatic groups and demic diffusion in the spread of Tai-Kadai languages.

Hum Genet 2017 01 11;136(1):85-98. Epub 2016 Nov 11.

Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany.

The Tai-Kadai (TK) language family is thought to have originated in southern China and spread to Thailand and Laos, but it is not clear if TK languages spread by demic diffusion (i.e., a migration of people from southern China) or by cultural diffusion, with native Austroasiatic (AA) speakers switching to TK languages. To address this and other questions, we obtained 1234 complete mtDNA genome sequences from 51 TK and AA groups from Thailand and Laos. We find high genetic heterogeneity across the region, with 212 different haplogroups, and significant genetic differentiation among different samples from the same ethnolinguistic group. TK groups are more genetically homogeneous than AA groups, with the latter exhibiting more ancient/basal mtDNA lineages, and showing more drift effects. Modeling of demic diffusion, cultural diffusion, and admixture scenarios consistently supports the spread of TK languages by demic diffusion.
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http://dx.doi.org/10.1007/s00439-016-1742-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5214972PMC
January 2017

Effect of migration patterns on maternal genetic structure: a case of Tai-Kadai migration from China to Thailand.

J Hum Genet 2017 Feb 8;62(2):223-228. Epub 2016 Sep 8.

Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.

The migration of the Tai-Kadai speaking people from southern China to northern Thailand over the past hundreds of years has revealed numerous patterns that have likely been influenced by routes, purposes and periods of time. To study the effects of different migration patterns on Tai-Kadai maternal genetic structure, mitochondrial DNA hypervariable region I sequences from the Yong and the Lue people having well-documented histories in northern Thailand were analyzed. Although the Yong and Lue people were historically close relatives who shared Xishuangbanna Dai ancestors, significant genetic differences have been observed among them. The Yong people who have been known to practice mass migration have exhibited a closer genetic affinity to their Dai ancestors than have the Lue people. Genetic heterogeneity and a sudden reduced effective population size within the Lue group is likely a direct result of the circumstances of the founder effect.
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http://dx.doi.org/10.1038/jhg.2016.112DOI Listing
February 2017

Genomic validation of the differential preservation of population history in modern human cranial anatomy.

Am J Phys Anthropol 2017 01 4;162(1):170-179. Epub 2016 Aug 4.

Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Eberhard Karls Universität Tübingen, Tübingen, Baden-Württemberg, D-72070, Germany.

Objectives: In modern humans, the significant correlation between neutral genetic loci and cranial anatomy suggests that the cranium preserves a population history signature. However, there is disagreement on whether certain parts of the cranium preserve this signature to a greater degree than other parts. It is also unclear how different quantitative measures of phenotype affect the association of genetic variation and anatomy. Here, we revisit these matters by testing the correlation of genetic distances and various phenotypic distances for ten modern human populations.

Materials And Methods: Geometric morphometric shape data from the crania of adult individuals (n = 224) are used to calculate phenotypic P , Procrustes, and Mahalanobis distances. We calculate their correlation to neutral genetic distances, F , derived from single nucleotide polymorphisms (SNPs). We subset the cranial data into landmark configurations that include the neurocranium, the face, and the temporal bone in order to evaluate whether these cranial regions are differentially correlated to neutral genetic variation.

Results: Our results show that P , Mahalanobis, and Procrustes distances are correlated with F distances to varying degrees. They indicate that overall cranial shape is significantly correlated with neutral genetic variation. Of the component parts examined, P distances for both the temporal bone and the face have a stronger association with F distances than the neurocranium. When controlling for population divergence time, only the whole cranium and the temporal bone have a statistically significant association with F distances.

Discussion: Our results confirm that the cranium, as a whole, and the temporal bone can be used to reconstruct modern human population history.
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http://dx.doi.org/10.1002/ajpa.23060DOI Listing
January 2017

Demographic History of the Genus Pan Inferred from Whole Mitochondrial Genome Reconstructions.

Genome Biol Evol 2016 07 3;8(6):2020-30. Epub 2016 Jul 3.

Departament de Ciències Experimentals i de la Salut, Institut de Biologia Evolutiva (CSIC-UPF), Barcelona, Spain Catalan Institution of Research and Advanced Studies (ICREA), Passeig de Lluís Companys, Barcelona, Spain CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain

The genus Pan is the closest genus to our own and it includes two species, Pan paniscus (bonobos) and Pan troglodytes (chimpanzees). The later is constituted by four subspecies, all highly endangered. The study of the Pan genera has been incessantly complicated by the intricate relationship among subspecies and the statistical limitations imposed by the reduced number of samples or genomic markers analyzed. Here, we present a new method to reconstruct complete mitochondrial genomes (mitogenomes) from whole genome shotgun (WGS) datasets, mtArchitect, showing that its reconstructions are highly accurate and consistent with long-range PCR mitogenomes. We used this approach to build the mitochondrial genomes of 20 newly sequenced samples which, together with available genomes, allowed us to analyze the hitherto most complete Pan mitochondrial genome dataset including 156 chimpanzee and 44 bonobo individuals, with a proportional contribution from all chimpanzee subspecies. We estimated the separation time between chimpanzees and bonobos around 1.15 million years ago (Mya) [0.81-1.49]. Further, we found that under the most probable genealogical model the two clades of chimpanzees, Western + Nigeria-Cameroon and Central + Eastern, separated at 0.59 Mya [0.41-0.78] with further internal separations at 0.32 Mya [0.22-0.43] and 0.16 Mya [0.17-0.34], respectively. Finally, for a subset of our samples, we compared nuclear versus mitochondrial genomes and we found that chimpanzee subspecies have different patterns of nuclear and mitochondrial diversity, which could be a result of either processes affecting the mitochondrial genome, such as hitchhiking or background selection, or a result of population dynamics.
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http://dx.doi.org/10.1093/gbe/evw124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4943195PMC
July 2016

Formal linguistics as a cue to demographic history.

J Anthropol Sci 2016 Jun 11;94:147-55. Epub 2015 Apr 11.

Dipartimento di Biologia ed Evoluzione, Universitá di Ferrara, Via Luigi Borsari 46, 44100 Ferrara, Italy.

Beyond its theoretical success, the development of molecular genetics has brought about the possibility of extraordinary progress in the study of classification and in the inference of the evolutionary history of many species and populations. A major step forward was represented by the availability of extremely large sets of molecular data suited to quantitative and computational treatments. In this paper, we argue that even in cognitive sciences, purely theoretical progress in a discipline such as linguistics may have analogous impact. Thus, exactly on the model of molecular biology, we propose to unify two traditionally unrelated lines of linguistic investigation: 1) the formal study of syntactic variation (parameter theory) in the biolinguistic program; 2) the reconstruction of relatedness among languages (phylogenetic taxonomy). The results of our linguistic analysis have thus been plotted against data from population genetics and the correlations have turned out to be largely significant: given a non-trivial set of languages/populations, the description of their variation provided by the comparison of systematic parametric analysis and molecular anthropology informatively recapitulates their history and relationships. As a result, we can claim that the reality of some parametric model of the language faculty and language acquisition/transmission (more broadly of generative grammar) receives strong and original support from its historical heuristic power. Then, on these grounds, we can begin testing Darwin's prediction that, when properly generated, the trees of human populations and of their languages should eventually turn out to be significantly parallel.
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http://dx.doi.org/10.4436/JASS.94031DOI Listing
June 2016

The Uromodulin Gene Locus Shows Evidence of Pathogen Adaptation through Human Evolution.

J Am Soc Nephrol 2016 Oct 10;27(10):2983-2996. Epub 2016 Mar 10.

Institute of Physiology, University of Zurich, Zurich, Switzerland

Common variants in the UMOD gene encoding uromodulin, associated with risk of hypertension and CKD in the general population, increase UMOD expression and urinary excretion of uromodulin, causing salt-sensitive hypertension and renal lesions. To determine the effect of selective pressure on variant frequency, we investigated the allelic frequency of the lead UMOD variant rs4293393 in 156 human populations, in eight ancient human genomes, and in primate genomes. The T allele of rs4293393, associated with CKD risk, has high frequency in most modern populations and was the one detected in primate genomes. In contrast, we identified only the derived, C allele in Denisovan and Neanderthal genomes. The distribution of the UMOD ancestral allele did not follow the ancestral susceptibility model observed for variants associated with salt-sensitive hypertension. Instead, the global frequencies of the UMOD alleles significantly correlated with pathogen diversity (bacteria, helminths) and prevalence of antibiotic-resistant urinary tract infections (UTIs). The inverse correlation found between urinary levels of uromodulin and markers of UTIs in the general population substantiates the link between UMOD variants and protection against UTIs. These data strongly suggest that the UMOD ancestral allele, driving higher urinary excretion of uromodulin, has been kept at a high frequency because of its protective effect against UTIs.
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http://dx.doi.org/10.1681/ASN.2015070830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042664PMC
October 2016

Recent Selection Changes in Human Genes under Long-Term Balancing Selection.

Mol Biol Evol 2016 06 1;33(6):1435-47. Epub 2016 Feb 1.

Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

Balancing selection is an important evolutionary force that maintains genetic and phenotypic diversity in populations. Most studies in humans have focused on long-standing balancing selection, which persists over long periods of time and is generally shared across populations. But balanced polymorphisms can also promote fast adaptation, especially when the environment changes. To better understand the role of previously balanced alleles in novel adaptations, we analyzed in detail four loci as case examples of this mechanism. These loci show hallmark signatures of long-term balancing selection in African populations, but not in Eurasian populations. The disparity between populations is due to changes in allele frequencies, with intermediate frequency alleles in Africans (likely due to balancing selection) segregating instead at low- or high-derived allele frequency in Eurasia. We explicitly tested the support for different evolutionary models with an approximate Bayesian computation approach and show that the patterns in PKDREJ, SDR39U1, and ZNF473 are best explained by recent changes in selective pressure in certain populations. Specifically, we infer that alleles previously under long-term balancing selection, or alleles linked to them, were recently targeted by positive selection in Eurasian populations. Balancing selection thus likely served as a source of functional alleles that mediated subsequent adaptations to novel environments.
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http://dx.doi.org/10.1093/molbev/msw023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4909129PMC
June 2016

Early modern human dispersal from Africa: genomic evidence for multiple waves of migration.

Investig Genet 2015 6;6:13. Epub 2015 Nov 6.

Department of Life Sciences and Biotechnologies, University of Ferrara, Ferrara, Italy.

Background: Anthropological and genetic data agree in indicating the African continent as the main place of origin for anatomically modern humans. However, it is unclear whether early modern humans left Africa through a single, major process, dispersing simultaneously over Asia and Europe, or in two main waves, first through the Arab Peninsula into southern Asia and Oceania, and later through a northern route crossing the Levant.

Results: Here, we show that accurate genomic estimates of the divergence times between European and African populations are more recent than those between Australo-Melanesia and Africa and incompatible with the effects of a single dispersal. This difference cannot possibly be accounted for by the effects of either hybridization with archaic human forms in Australo-Melanesia or back migration from Europe into Africa. Furthermore, in several populations of Asia we found evidence for relatively recent genetic admixture events, which could have obscured the signatures of the earliest processes.

Conclusions: We conclude that the hypothesis of a single major human dispersal from Africa appears hardly compatible with the observed historical and geographical patterns of genome diversity and that Australo-Melanesian populations seem still to retain a genomic signature of a more ancient divergence from Africa.
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http://dx.doi.org/10.1186/s13323-015-0030-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636834PMC
November 2015

Origin and dynamics of admixture in Brazilians and its effect on the pattern of deleterious mutations.

Proc Natl Acad Sci U S A 2015 Jul 29;112(28):8696-701. Epub 2015 Jun 29.

Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil;

While South Americans are underrepresented in human genomic diversity studies, Brazil has been a classical model for population genetics studies on admixture. We present the results of the EPIGEN Brazil Initiative, the most comprehensive up-to-date genomic analysis of any Latin-American population. A population-based genome-wide analysis of 6,487 individuals was performed in the context of worldwide genomic diversity to elucidate how ancestry, kinship, and inbreeding interact in three populations with different histories from the Northeast (African ancestry: 50%), Southeast, and South (both with European ancestry >70%) of Brazil. We showed that ancestry-positive assortative mating permeated Brazilian history. We traced European ancestry in the Southeast/South to a wider European/Middle Eastern region with respect to the Northeast, where ancestry seems restricted to Iberia. By developing an approximate Bayesian computation framework, we infer more recent European immigration to the Southeast/South than to the Northeast. Also, the observed low Native-American ancestry (6-8%) was mostly introduced in different regions of Brazil soon after the European Conquest. We broadened our understanding of the African diaspora, the major destination of which was Brazil, by revealing that Brazilians display two within-Africa ancestry components: one associated with non-Bantu/western Africans (more evident in the Northeast and African Americans) and one associated with Bantu/eastern Africans (more present in the Southeast/South). Furthermore, the whole-genome analysis of 30 individuals (42-fold deep coverage) shows that continental admixture rather than local post-Columbian history is the main and complex determinant of the individual amount of deleterious genotypes.
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http://dx.doi.org/10.1073/pnas.1504447112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507185PMC
July 2015

Across language families: Genome diversity mirrors linguistic variation within Europe.

Am J Phys Anthropol 2015 Aug 8;157(4):630-40. Epub 2015 Jun 8.

Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.

Objectives: The notion that patterns of linguistic and biological variation may cast light on each other and on population histories dates back to Darwin's times; yet, turning this intuition into a proper research program has met with serious methodological difficulties, especially affecting language comparisons. This article takes advantage of two new tools of comparative linguistics: a refined list of Indo-European cognate words, and a novel method of language comparison estimating linguistic diversity from a universal inventory of grammatical polymorphisms, and hence enabling comparison even across different families. We corroborated the method and used it to compare patterns of linguistic and genomic variation in Europe.

Materials And Methods: Two sets of linguistic distances, lexical and syntactic, were inferred from these data and compared with measures of geographic and genomic distance through a series of matrix correlation tests. Linguistic and genomic trees were also estimated and compared. A method (Treemix) was used to infer migration episodes after the main population splits.

Results: We observed significant correlations between genomic and linguistic diversity, the latter inferred from data on both Indo-European and non-Indo-European languages. Contrary to previous observations, on the European scale, language proved a better predictor of genomic differences than geography. Inferred episodes of genetic admixture following the main population splits found convincing correlates also in the linguistic realm.

Discussion: These results pave the ground for previously unfeasible cross-disciplinary analyses at the worldwide scale, encompassing populations of distant language families.
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http://dx.doi.org/10.1002/ajpa.22758DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095809PMC
August 2015

Large-scale recent expansion of European patrilineages shown by population resequencing.

Nat Commun 2015 May 19;6:7152. Epub 2015 May 19.

Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK.

The proportion of Europeans descending from Neolithic farmers ∼ 10 thousand years ago (KYA) or Palaeolithic hunter-gatherers has been much debated. The male-specific region of the Y chromosome (MSY) has been widely applied to this question, but unbiased estimates of diversity and time depth have been lacking. Here we show that European patrilineages underwent a recent continent-wide expansion. Resequencing of 3.7 Mb of MSY DNA in 334 males, comprising 17 European and Middle Eastern populations, defines a phylogeny containing 5,996 single-nucleotide polymorphisms. Dating indicates that three major lineages (I1, R1a and R1b), accounting for 64% of our sample, have very recent coalescent times, ranging between 3.5 and 7.3 KYA. A continuous swathe of 13/17 populations share similar histories featuring a demographic expansion starting ∼ 2.1-4.2 KYA. Our results are compatible with ancient MSY DNA data, and contrast with data on mitochondrial DNA, indicating a widespread male-specific phenomenon that focuses interest on the social structure of Bronze Age Europe.
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http://dx.doi.org/10.1038/ncomms8152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4441248PMC
May 2015

Genetic and linguistic correlation of the Kra-Dai-speaking groups in Thailand.

J Hum Genet 2015 Jul 2;60(7):371-80. Epub 2015 Apr 2.

Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand.

The Kra-Dai linguistic family includes Thai and Lao as well as a great number of languages spoken by ethnic minorities in Southeast Asia. In Thailand, a dozen of other Kra-Dai languages are spoken in addition to Thai, the national language. The genetic structure of the Kra-Dai-speaking populations in Thailand has been studied extensively using uniparentally inherited markers. To extend this line of genetic investigation, this study used 15 autosomal microsatellites of 500 individuals from 11 populations, belonging to nine Kra-Dai ethnicities, namely, the Kaleung, Phu Thai, Saek, Nyo, Lao Isan, Yuan, Black Tai, Phuan and Lue. These ethnolinguistic groups are dispersed in three different geographic regions of Thailand, that is, Northern, Northeastern and Central. The results show a very low average of pairwised F(st) (0.0099), as well as no population substructure based on STRUCTURE analysis, indicating genetic homogeneity within the Kra-Dai-speaking group, possibly owing to shared linguistic ancestry. The Mantel test, an analysis of molecular variance, and the approximate Bayesian computation procedure employed to evaluate potential factors for driving genetic diversity revealed that language is the predominant factor affecting genetic variations, whereas geography is not. The result of distance-based clustering analyses and spatial analysis of molecular variance revealed genetic distinctions of some populations, reflecting the effects of genetic drift and gene flow on allele frequency within populations, in concordance with the result of R-matrix regression. The genetic and linguistic affiliations of the contemporary Kra-Dai-speaking groups are consistent with each other despite certain deviation due to various evolutionary factors that may have occurred during their migrations and resettlements.
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http://dx.doi.org/10.1038/jhg.2015.32DOI Listing
July 2015

The Neanderthal in the karst: First dating, morphometric, and paleogenetic data on the fossil skeleton from Altamura (Italy).

J Hum Evol 2015 May 21;82:88-94. Epub 2015 Mar 21.

Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy. Electronic address:

In 1993, a fossil hominin skeleton was discovered in the karst caves of Lamalunga, near Altamura, in southern Italy. Despite the fact that this specimen represents one of the most extraordinary hominin specimens ever found in Europe, for the last two decades our knowledge of it has been based purely on the documented on-site observations. Recently, the retrieval from the cave of a fragment of bone (part of the right scapula) allowed the first dating of the individual, the quantitative analysis of a diagnostic morphological feature, and a preliminary paleogenetic characterization of this hominin skeleton from Altamura. Overall, the results concur in indicating that it belongs to the hypodigm of Homo neanderthalensis, with some phenetic peculiarities that appear consistent with a chronology ranging from 172 ± 15 ka to 130.1 ± 1.9 ka. Thus, the skeleton from Altamura represents the most ancient Neanderthal from which endogenous DNA has ever been extracted.
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http://dx.doi.org/10.1016/j.jhevol.2015.02.007DOI Listing
May 2015

Genealogical relationships between early medieval and modern inhabitants of Piedmont.

PLoS One 2015 30;10(1):e0116801. Epub 2015 Jan 30.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, 44121 Ferrara, Italy.

In the period between 400 to 800 AD, also known as the period of the Barbarian invasions, intense migration is documented in the historical record of Europe. However, little is known about the demographic impact of these historical movements, potentially ranging from negligible to substantial. As a pilot study in a broader project on Medieval Europe, we sampled 102 specimens from 5 burial sites in Northwestern Italy, archaeologically classified as belonging to Lombards or Longobards, a Germanic people ruling over a vast section of the Italian peninsula from 568 to 774. We successfully amplified and typed the mitochondrial hypervariable region I (HVR-I) of 28 individuals. Comparisons of genetic diversity with other ancient populations and haplotype networks did not suggest that these samples are heterogeneous, and hence allowed us to jointly compare them with three isolated contemporary populations, and with a modern sample of a large city, representing a control for the effects of recent immigration. We then generated by serial coalescent simulations 16 millions of genealogies, contrasting a model of genealogical continuity with one in which the contemporary samples are genealogically independent from the medieval sample. Analyses by Approximate Bayesian Computation showed that the latter model fits the data in most cases, with one exception, Trino Vercellese, in which the evidence was compatible with persistence up to the present time of genetic features observed among this early medieval population. We conclude that it is possible, in general, to detect evidence of genealogical ties between medieval and specific modern populations. However, only seldom did mitochondrial DNA data allow us to reject with confidence either model tested, which indicates that broader analyses, based on larger assemblages of samples and genetic markers, are needed to understand in detail the effects of medieval migration.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0116801PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312042PMC
October 2015

Bayesian inferences suggest that Amazon Yunga Natives diverged from Andeans less than 5000 ybp: implications for South American prehistory.

BMC Evol Biol 2014 Sep 30;14:174. Epub 2014 Sep 30.

Background: Archaeology reports millenary cultural contacts between Peruvian Coast-Andes and the Amazon Yunga, a rainforest transitional region between Andes and Lower Amazonia. To clarify the relationships between cultural and biological evolution of these populations, in particular between Amazon Yungas and Andeans, we used DNA-sequence data, a model-based Bayesian approach and several statistical validations to infer a set of demographic parameters.

Results: We found that the genetic diversity of the Shimaa (an Amazon Yunga population) is a subset of that of Quechuas from Central-Andes. Using the Isolation-with-Migration population genetics model, we inferred that the Shimaa ancestors were a small subgroup that split less than 5300 years ago (after the development of complex societies) from an ancestral Andean population. After the split, the most plausible scenario compatible with our results is that the ancestors of Shimaas moved toward the Peruvian Amazon Yunga and incorporated the culture and language of some of their neighbors, but not a substantial amount of their genes. We validated our results using Approximate Bayesian Computations, posterior predictive tests and the analysis of pseudo-observed datasets.

Conclusions: We presented a case study in which model-based Bayesian approaches, combined with necessary statistical validations, shed light into the prehistoric demographic relationship between Andeans and a population from the Amazon Yunga. Our results offer a testable model for the peopling of this large transitional environmental region between the Andes and the Lower Amazonia. However, studies on larger samples and involving more populations of these regions are necessary to confirm if the predominant Andean biological origin of the Shimaas is the rule, and not the exception.
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http://dx.doi.org/10.1186/s12862-014-0174-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4189748PMC
September 2014