Genomic history of the Italian population recapitulates key evolutionary dynamics of both Continental and Southern Europeans

• Published in: BMC biology Vol. 18; no. 1; pp. 51 - 19
• Main Authors: Sazzini, Marco, Abondio, Paolo, Sarno, Stefania, Gnecchi-Ruscone, Guido Alberto, Ragno, Matteo, Giuliani, Cristina, De Fanti, Sara, Ojeda-Granados, Claudia, Boattini, Alessio, Marquis, Julien, Valsesia, Armand, Carayol, Jerome, Raymond, Frederic, Pirazzini, Chiara, Marasco, Elena, Ferrarini, Alberto, Xumerle, Luciano, Collino, Sebastiano, Mari, Daniela, Arosio, Beatrice, Monti, Daniela, Passarino, Giuseppe, D'Aquila, Patrizia, Pettener, Davide, Luiselli, Donata, Castellani, Gastone, Delledonne, Massimo, Descombes, Patrick, Franceschi, Claudio, Garagnani, Paolo
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 22.05.2020; BioMed Central; BMC
• Subjects: Adaptation; Analysis; Archaeology; Biodiversity; Biological activity; Datasets; Demographic inference; Deoxyribonucleic acid; Divergence; DNA; DNA, Ancient - analysis; Evolution; Evolution & development; Evolution, Molecular; Evolutionary genetics; Evolutionary medicine; Gene flow; Gene pool; Gene sequencing; Genealogy; Genes; Genetic diversity; Genetic research; Genetic variance; Genetic Variation; Genome, Human; Genomes; Genomics; Humans; Insulin; Italian population; Italy; Medicin och hälsovetenskap; Mitochondrial DNA; Neolithic; Polygenic adaptation; Population; Population biology; Population dynamics; Population genetics; Population structure; Single-nucleotide polymorphism; Stone Age; Ultraviolet radiation; White People; Whole-genome sequences; Y chromosomes; Italy; Eastern Europe; Mediterranean Sea; Middle East; Southern Europe; Crete; Demographic inference; Whole-genome sequences; Polygenic adaptation; Evolutionary medicine; Italian population
• ISSN: 1741-7007; 1741-7007
• DOI: 10.1186/s12915-020-00778-4

The cline of human genetic diversity observable across Europe is recapitulated at a micro-geographic scale by variation within the Italian population. Besides resulting from extensive gene flow, this might be ascribable also to local adaptations to diverse ecological contexts evolved by people who anciently spread along the Italian Peninsula. Dissecting the evolutionary history of the ancestors of present-day Italians may thus improve the understanding of demographic and biological processes that contributed to shape the gene pool of European populations. However, previous SNP array-based studies failed to investigate the full spectrum of Italian variation, generally neglecting low-frequency genetic variants and examining a limited set of small effect size alleles, which may represent important determinants of population structure and complex adaptive traits. To overcome these issues, we analyzed 38 high-coverage whole-genome sequences representative of population clusters at the opposite ends of the cline of Italian variation, along with a large panel of modern and ancient Euro-Mediterranean genomes. We provided evidence for the early divergence of Italian groups dating back to the Late Glacial and for Neolithic and distinct Bronze Age migrations having further differentiated their gene pools. We inferred adaptive evolution at insulin-related loci in people from Italian regions with a temperate climate, while possible adaptations to pathogens and ultraviolet radiation were observed in Mediterranean Italians. Some of these adaptive events may also have secondarily modulated population disease or longevity predisposition. We disentangled the contribution of multiple migratory and adaptive events in shaping the heterogeneous Italian genomic background, which exemplify population dynamics and gene-environment interactions that played significant roles also in the formation of the Continental and Southern European genomic landscapes.