The multiple maternal legacy of the Late Iron Age group of Urville-Nacqueville (France, Normandy) documents a long-standing genetic contact zone in northwestern France

The compilation of archaeological and genetic data for ancient European human groups has provided persuasive evidence for a complex series of migrations, population replacements and admixture until the Bronze Age. If the Bronze-to-Iron Age transition has been well documented archaeologically, ancient DNA (aDNA) remains rare for the latter period and does not precisely reflect the genetic diversity of European Celtic groups. In order to document the evolution of European communities, we analysed 45 individuals from the Late Iron Age (La Tène) Urville-Nacqueville necropolis in northwestern France, a region recognized as a major cultural contact zone between groups from both sides of the Channel. The characterization of 37 HVS-I mitochondrial sequences and 40 haplogroups provided the largest maternal gene pool yet recovered for the European Iron Age. First, descriptive analyses allowed us to demonstrate the presence of substantial amounts of steppe-related mitochondrial ancestry in the community, which is consistent with the expansion of Bell Beaker groups bearing an important steppe legacy in northwestern Europe at approximately 2500 BC. Second, maternal genetic affinities highlighted with Bronze Age groups from Great Britain and the Iberian Peninsula regions tends to support the idea that the continuous cultural exchanges documented archaeologically across the Channel and along the Atlantic coast (during and after the Bronze Age period) were accompanied by significant gene flow. Lastly, our results suggest a maternal genetic continuity between Bronze Age and Iron Age groups that would argue in favour of a cultural transition linked to progressive local economic changes rather than to a massive influx of allochthone groups. The palaeogenetic data gathered for the Urville-Nacqueville group constitute an important step in the biological characterization of European Iron age groups. Clearly, more numerous and diachronic aDNA data are needed to fully understand the complex relationship between the cultural and biological evolution of groups from the period

New insights on Neolithic food and mobility patterns of Mediterranean coastal populations

The aims of this research are to explore the diet, mobility, social organization, and environmental exploitation patterns of early Mediterranean farmers, particularly the role of marine and plant resources in these foodways. In addition, this work strives to document possible gendered patterns of behavior linked to the neolithization of this ecologically rich area. To achieve this, a set of multiproxy analyses (isotopic analyses, dental calculus, microremains analysis, ancient DNA) were performed on an exceptional deposit (n = 61) of human remains from the Les Bréguières site (France), dating to the transition of the sixth to the fifth millennium BCE. Materials and Methods: The samples used in this study were excavated from the Les Bréguières site (Mougins, Alpes-Maritimes, France), located along the southeastern Mediterranean coastline of France. Stable isotope analyses (C, N) on bone collagen (17 coxal bones, 35 craniofacial elements) were performed as a means to infer protein intake during tissue development. Sulfur isotope ratios were used as indicators of geographical and environmental points of origin. The study of ancient dental calculus helped document the consumption of plants. Strontium isotope analysis on tooth enamel (n = 56) was conducted to infer human provenance and territorial mobility. Finally, ancient DNA analysis was performed to study maternal versus paternal diversity within this Neolithic group (n = 30). Results: Stable isotope ratios for human bones range from −20.3 to −18.1¿ for C, from 8.9 to 11.1¿ for N and from 6.4 to 15¿ for S. Domestic animal data range from −22.0 to −20.2¿ for C, from 4.1 to 6.9¿ for N, and from 10.2 to 12.5¿ for S. Human enamel 87Sr/86Sr range from 0.7081 to 0.7102, slightly wider than the animal range (between 0.7087 and 0.7096). Starch and phytolith microremains were recovered as well as other types of remains (e.g., hairs, diatoms, fungal spores). Starch grains include Triticeae type and phytolith includes dicotyledons and monocot types as panicoid grasses. Mitochondrial DNA characterized eight different maternal lineages: H1, H3, HV (5.26%), J (10.53%), J1, K, T (5.2%), and U5 (10.53%) but no sample yielded reproducible Y chromosome SNPs, preventing paternal lineage characterization. Discussion: Carbon and nitrogen stable isotope ratios indicate a consumption of protein by humans mainly focused on terrestrial animals and possible exploitation of marine resources for one male and one undetermined adult. Sulfur stable isotope ratios allowed distinguishing groups with different geographical origins, including two females possibly more exposed to the sea spray effect. While strontium isotope data do not indicate different origins for the individuals, mitochondrial lineage diversity from petrous bone DNA suggests the burial includes genetically differentiated groups or a group practicing patrilocality. Moreover, the diversity of plant microremains recorded in dental calculus provide the first evidence that the groups of Les Bréguières consumed a wide breadth of plant foods (as cereals and wild taxa) that required access to diverse environments. This transdisciplinary research paves the way for new perspectives and highlights the relevance for novel research of contexts (whether recently discovered or in museum collections) excavated near shorelines, due to the richness of the biodiversity and the wide range of edible resources available

Investigating mitochondrial DNA relationships in Neolithic Western Europe through serial coalescent simulations

Recent ancient DNA studies on European Neolithic human populations have provided persuasive evidence of a major migration of farmers originating from the Aegean, accompanied by sporadic hunter-gatherer admixture into early Neolithic populations, but increasing toward the Late Neolithic. In this context, ancient mitochondrial DNA data collected from the Neolithic necropolis of Gurgy (Paris Basin, France), the largest mitochondrial DNA sample obtained from a single archeological site for the Early/Middle Neolithic period, indicate little differentiation from farmers associated to both the Danubian and Mediterranean Neolithic migration routes, as well as from Western European hunter-gatherers. To test whether this pattern of differentiation could arise in a single unstructured population by genetic drift alone, we used serial coalescent simulations. We explore female effective population size parameter combinations at the time of the colonization of Europe 45000 years ago and the most recent of the Neolithic samples analyzed in this study 5900 years ago, and identify conditions under which population panmixia between hunter-gatherers/Early-Middle Neolithic farmers and Gurgy cannot be rejected. In relation to other studies on the current debate of the origins of Europeans, these results suggest increasing hunter-gatherer admixture into farmers' group migrating farther west in Europe.European Journal of Human Genetics advance online publication, 28 December 2016; doi:10.1038/ejhg.2016.180

Origin and mobility of Iron Age Gaulish groups in present-day France revealed through archaeogenomics

The Iron Age period occupies an important place in French history, as the Gauls are regularly presented as the direct ancestors of the extant French population. We documented here the genomic diversity of Iron Age communities originating from six French regions. The 49 acquired genomes permitted us to highlight an absence of discontinuity between Bronze Age and Iron Age groups in France, lending support to a cultural transition linked to progressive local economic changes rather than to a massive influx of allochthone groups. Genomic analyses revealed strong genetic homogeneity among the regional groups associated with distinct archaeological cultures. This genomic homogenisation appears to be linked to individuals’ mobility between regions as well as gene flow with neighbouring groups from England and Spain. Thus, the results globally support a common genomic legacy for the Iron Age population of modern-day France that could be linked to recurrent gene flow between culturally differentiated communities

DNA-based control of oak wood geographic origin in the context of the cooperage industry

The recent growth of the French barrel industry, leading to increased importations of oak wood and a general lack of wood origin guarantee, has resulted in the demand for a reliable technique permitting to control the provenance of oak wood. In this study we propose to adapt wood traceability technique using chloroplast DNA markers to this industrial context. The retrieval of DNA and haplotype determination has been tested on different types of wood samples that can be collected in cooperage firms, and a clear effect of wood treatment on DNA degradation has been observed. Despite the poor quantity and quality of DNA retrieved from staves, haplotypes could be determined on a large proportion of the samples, permitting to check the genetic conformity of woods with announced provenances. In several cases, our study proved the existence of unlabeled oak woods originating from eastern Europe and the incorrect use of the names of famous French forestsL'importation croissante de bois de chêne et le manque de garantie sur son origine, liés à l'expansion récente de la tonnellerie française, rendent nécessaire la mise au point d'une technique fiable permettant de contrôler l'origine des bois de chêne. Dans cette étude, nous avons cherché à adapter, pour ce secteur industriel, les méthodes moléculaires de traçabilité des bois de chêne utilisant les marqueurs chloroplastiques. La qualité et la quantité de l'ADN extrait et la caractérisation des haplotypes ont alors été évalués sur les différents types d'échantillons de bois rencontrés dans les tonnelleries. Nous avons pu démontrer un effet net des différents traitements du bois sur la dégradation de l'ADN. Cependant, malgré la faible qualité et quantité d'ADN extrait des bois de merrains, les haplotypes ont pu être déterminés sur une large proportion des échantillons, permettant de tester la conformité des bois avec l'origine annoncée. Dans plusieurs cas, nous avons pu mettre en évidence l'existence de bois mal identifiés, provenant de l'est de l'Europe, ainsi que l'utilisation abusive des noms des provenances françaises renommée

Use of chloroplast microsatellites to differentiate oak populations

The possibility to use chloroplast microsatellites (cpSSRs) instead of restriction analysis of PCR-amplified DNA fragments to differentiate oak populations was tested in two economically important tree species: Quercus petraea and Quercus robur. The level and pattern of inter- and intraspecific cpDNA variation were studied over 48 French populations using a total of 24 cpSSR loci. The same pattern of low intrapopulation diversity and high population differentiation was noted with both types of markers, since there was an almost total redundancy of haplotypes identified with both techniques. Overall, our results indicate that chloroplast microsatellites can be used for haplotype discrimination in many contexts including certification or traceability of oak material.Utilisation des microsatellites chloroplastiques pour différencier des populations de chênes. Nous avons cherché à comparer l’efficacité de deux types de marqueurs chloroplastiques, les marqueurs microsatellites (cpSSR) et marqueurs PCR-RFLP (cpRFLP), à différencier des populations de chênes sessiles et pédonculés, deux espèces d’arbres forestiers économiquement importantes. Le niveau et la structuration de la diversité inter et intra-spécifique ont été mesurés au sein de 48 populations françaises au travers de l’analyse de 24 microsatellites chloroplastiques. Une faible diversité intra-population, ainsi qu’une forte différenciation des populations de chênes ont pu être mesurées à l’aide des deux types de marqueurs, du fait d’une redondance quasi-complète des haplotypes identifiés par les deux techniques. Nos résultats indiquent donc que les marqueurs microsatellites chloroplastiques peuvent être utilisés pour la distinction d’haplotypes et de populations de chênes dans le cadre de la certification ou de la traçabilité de matériel forestier (graines, plants, bois)

European Neolithization and ancient DNA : an assessment

International audienc

Efficient mitigation of founder effects during the establishment of a leading-edge oak population

Numerous plant species are shifting their range polewards in response to ongoing climate change. Range shifts typically involve the repeated establishment and growth of leading-edge populations well ahead of the main species range. How these populations recover from founder events and associated diversity loss remains poorly understood. To help fill this gap, we exhaustively investigated a newly established population of holm oak (Quercus ilex) growing more than 30 km ahead of the nearest larger stands. Pedigree reconstructions showed that plants belong to two non-overlapping generations and that the whole population originates from only two founder trees. The four first-generation trees that have reached maturity showed disparate mating patterns despite being full-sibs. Long-distance pollen immigration was notable despite the strong isolation of the stand: 6 per cent gene flow events in acorns collected on the trees (n = 255), and as much as 27 per cent among their established offspring (n = 33). Our results show that isolated leading-edge populations of wind-pollinated forest trees can rapidly restore their genetic diversity through the interacting effects of efficient long-distance pollen flow and purging of inbred individuals during recruitment. They imply that range expansions of these species are primarily constrained by initial propagule arrival rather than by subsequent gene flow

European Neolithization and ancient DNA : an assessment

International audienc