New Insights into the Lake Chad Basin Population Structure Revealed by High-Throughput Genotyping of Mitochondrial DNA Coding SNPs

BACKGROUND: Located in the Sudan belt, the Chad Basin forms a remarkable ecosystem, where several unique agricultural and pastoral techniques have been developed. Both from an archaeological and a genetic point of view, this region has been interpreted to be the center of a bidirectional corridor connecting West and East Africa, as well as a meeting point for populations coming from North Africa through the Saharan desert. METHODOLOGY/PRINCIPAL FINDINGS: Samples from twelve ethnic groups from the Chad Basin (n = 542) have been high-throughput genotyped for 230 coding region mitochondrial DNA (mtDNA) Single Nucleotide Polymorphisms (mtSNPs) using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry. This set of mtSNPs allowed for much better phylogenetic resolution than previous studies of this geographic region, enabling new insights into its population history. Notable haplogroup (hg) heterogeneity has been observed in the Chad Basin mirroring the different demographic histories of these ethnic groups. As estimated using a Bayesian framework, nomadic populations showed negative growth which was not always correlated to their estimated effective population sizes. Nomads also showed lower diversity values than sedentary groups. CONCLUSIONS/SIGNIFICANCE: Compared to sedentary population, nomads showed signals of stronger genetic drift occurring in their ancestral populations. These populations, however, retained more haplotype diversity in their hypervariable segments I (HVS-I), but not their mtSNPs, suggesting a more ancestral ethnogenesis. Whereas the nomadic population showed a higher Mediterranean influence signaled mainly by sub-lineages of M1, R0, U6, and U5, the other populations showed a more consistent sub-Saharan pattern. Although lifestyle may have an influence on diversity patterns and hg composition, analysis of molecular variance has not identified these differences. The present study indicates that analysis of mtSNPs at high resolution could be a fast and extensive approach for screening variation in population studies where labor-intensive techniques such as entire genome sequencing remain unfeasible

Saving traditional knowhow in agriculture

Chapter 15International audienceThe concept of agricultural knowhow here refers to the knowledge accumulated over centuries and that has been slowly carved by exchanges, confrontations, trade and the mixing of cultures even at very local levels throughout the Mediterranean. Although the differences between the North and South of the basin are strongly marked, each locality has traditionally enjoyed a unique identity and a strong individuality in its history. Closely related to the loss of traditional knowhow, the weakening of these identities is shaping a new Mediterranean. A Mediterranean that is northern and southern, local and global, technical and traditional, a constant rebalancing region that is a both complex and unstable. A Mediterranean where it is becoming urgent to save knowhow in danger of being marginalised (and depleted) and align it with the scientific advances of the past decade, in order to address in an integrated way, the various current and foreseeable crises that threaten the fragile balance supporting life in this basin. This chapter argues for the emergence of new production systems, breaking with the current trend of resource degradation and marginalisation of large rural areas, in order to meet these challenges. Agro ecology is presented here as one possible way to collectively live through this course in the cultural, scientific and economic evolution of the Mediterranean

Saving traditional knowhow in agriculture

Chapter 15International audienceThe concept of agricultural knowhow here refers to the knowledge accumulated over centuries and that has been slowly carved by exchanges, confrontations, trade and the mixing of cultures even at very local levels throughout the Mediterranean. Although the differences between the North and South of the basin are strongly marked, each locality has traditionally enjoyed a unique identity and a strong individuality in its history. Closely related to the loss of traditional knowhow, the weakening of these identities is shaping a new Mediterranean. A Mediterranean that is northern and southern, local and global, technical and traditional, a constant rebalancing region that is a both complex and unstable. A Mediterranean where it is becoming urgent to save knowhow in danger of being marginalised (and depleted) and align it with the scientific advances of the past decade, in order to address in an integrated way, the various current and foreseeable crises that threaten the fragile balance supporting life in this basin. This chapter argues for the emergence of new production systems, breaking with the current trend of resource degradation and marginalisation of large rural areas, in order to meet these challenges. Agro ecology is presented here as one possible way to collectively live through this course in the cultural, scientific and economic evolution of the Mediterranean

Préserver les savoirs traditionnels agricoles

Chapitre 15International audienceLa notion de savoir traditionnel agricole désigne les savoirs accumulés tout au long des siècles, que les échanges, les confrontations, le commerce et le brassage des cultures ont lentement construits jusqu’aux échelles les plus locales du bassin méditerranéen. Même s’il existe des différences marquées entre le nord et le sud du bassin, chaque localité a pu acquérir au cours de son histoire une identité propre et une forte individualité. L’affaiblissement de ces identités, intimement lié à la perte des connaissances traditionnelles, dessine aujourd’hui une nouvelle Méditerranée, à la fois nord et sud, locale et globale, technique et traditionnelle, ensemble complexe et instable en rééquilibrage constant, où il devient urgent de sauvegarder des savoirs en voie de marginalisation (et de disparition) et de les harmoniser avec les progrès scientifiques de la décennie écoulée, si l’on veut répondre de façon intégrée aux diverses crises actuelles et annoncées qui menacent les équilibres fragiles soutenant la vie dans le bassin. Ce chapitre plaide en faveur de l’émergence de nouveaux systèmes de production, en rupture avec la tendance actuelle à la dégradation des ressources et à la marginalisation des zones rurales. L’agroécologie est ici présentée comme l’une des voies possibles pour passer collectivement ce cap dans l’évolution culturelle, scientifique et économique du bassin méditerranéen

Préserver les savoirs traditionnels agricoles

Chapitre 15International audienceLa notion de savoir traditionnel agricole désigne les savoirs accumulés tout au long des siècles, que les échanges, les confrontations, le commerce et le brassage des cultures ont lentement construits jusqu’aux échelles les plus locales du bassin méditerranéen. Même s’il existe des différences marquées entre le nord et le sud du bassin, chaque localité a pu acquérir au cours de son histoire une identité propre et une forte individualité. L’affaiblissement de ces identités, intimement lié à la perte des connaissances traditionnelles, dessine aujourd’hui une nouvelle Méditerranée, à la fois nord et sud, locale et globale, technique et traditionnelle, ensemble complexe et instable en rééquilibrage constant, où il devient urgent de sauvegarder des savoirs en voie de marginalisation (et de disparition) et de les harmoniser avec les progrès scientifiques de la décennie écoulée, si l’on veut répondre de façon intégrée aux diverses crises actuelles et annoncées qui menacent les équilibres fragiles soutenant la vie dans le bassin. Ce chapitre plaide en faveur de l’émergence de nouveaux systèmes de production, en rupture avec la tendance actuelle à la dégradation des ressources et à la marginalisation des zones rurales. L’agroécologie est ici présentée comme l’une des voies possibles pour passer collectivement ce cap dans l’évolution culturelle, scientifique et économique du bassin méditerranéen

Saving traditional knowhow in agriculture

Chapter 15International audienceThe concept of agricultural knowhow here refers to the knowledge accumulated over centuries and that has been slowly carved by exchanges, confrontations, trade and the mixing of cultures even at very local levels throughout the Mediterranean. Although the differences between the North and South of the basin are strongly marked, each locality has traditionally enjoyed a unique identity and a strong individuality in its history. Closely related to the loss of traditional knowhow, the weakening of these identities is shaping a new Mediterranean. A Mediterranean that is northern and southern, local and global, technical and traditional, a constant rebalancing region that is a both complex and unstable. A Mediterranean where it is becoming urgent to save knowhow in danger of being marginalised (and depleted) and align it with the scientific advances of the past decade, in order to address in an integrated way, the various current and foreseeable crises that threaten the fragile balance supporting life in this basin. This chapter argues for the emergence of new production systems, breaking with the current trend of resource degradation and marginalisation of large rural areas, in order to meet these challenges. Agro ecology is presented here as one possible way to collectively live through this course in the cultural, scientific and economic evolution of the Mediterranean