Craniofacial morphometric variation and the biological history of the peopling of Sardinia

Spatial diffusion of surnames by long transhumance routes between highland and lowland: A study in Sardinia

RIASSUNTO.

Complete mitochondrial sequences from Mesolithic Sardinia

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.

The Osteological Collection of the University of Cagliari: From Early Neolithic to Modern Age

The Osteological Collection described in this paper is located at the Anthropology Laboratory annexed to the Sardinian Museum of Anthropology and Ethnography of the University of Cagliari. It has been created in 1953 by Carlo Maxia and comprises a large number of skeletal remains. At present the Collection consists of 11,854 human bones and continues to grow. The remains belong to different periods, beginning from the Early Neolithic and continuing to the Modern Age. The aim of this work is to provide information on the composition of this collection after the reorganization carried out in the last years.

Phenotypic variation of transitional forager-farmers in the Sonoran Desert

This study examines phenotypic variation and biological distances estimated using morphological traits from three Early Agricultural period (EAP) (2100 BC-AD 50) site-complexes in the Sonoran Desert of southern Arizona and northern Sonora. The hypothesis tested is that EAP forager-farmers were phenotypically homogenous as suggested by patterns in material culture and works to refine inferences regarding gene flow and biological affinity during subsistence transitions. Seven measurements from 62 EAP male and female crania were collected and used to calculate phenotypic variances, biological distances, and FST values with RMET 5.0 software. Analyses were applied to both pooled site-complex samples and to males and females separately. Results show differential variation between site-complex population samples, multiple significant biological distances, and significant FST values for the EAP regional sample that indicate widespread phenotypic heterogeneity rather than homogeneity. Significantly lower than expected variance in the Cienega Creek male sample is inferred to suggest a small closely related population present during the Cienega phase. Greater than expected male variation is attributed to higher frequencies of gene flow in the La Playa and Santa Cruz River site-complex samples. These EAP males are inferred to be more mobile across the Sonoran Desert landscape and representative of multiple biological affinities compared with females. This study provides evidence supporting the canalization of phenotypic variation when associated with human populations becoming increasingly sedentary due to transitioning subsistence practices.

Population genomic analysis of ancient and modern genomes yields new insights into the genetic ancestry of the Tyrolean Iceman and the genetic structure of Europe

Genome sequencing of the 5,300-year-old mummy of the Tyrolean Iceman, found in 1991 on a glacier near the border of Italy and Austria, has yielded new insights into his origin and relationship to modern European populations. A key finding of that study was an apparent recent common ancestry with individuals from Sardinia, based largely on the Y chromosome haplogroup and common autosomal SNP variation. Here, we compiled and analyzed genomic datasets from both modern and ancient Europeans, including genome sequence data from over 400 Sardinians and two ancient Thracians from Bulgaria, to investigate this result in greater detail and determine its implications for the genetic structure of Neolithic Europe. Using whole-genome sequencing data, we confirm that the Iceman is, indeed, most closely related to Sardinians. Furthermore, we show that this relationship extends to other individuals from cultural contexts associated with the spread of agriculture during the Neolithic transition, in contrast to individuals from a hunter-gatherer context. We hypothesize that this genetic affinity of ancient samples from different parts of Europe with Sardinians represents a common genetic component that was geographically widespread across Europe during the Neolithic, likely related to migrations and population expansions associated with the spread of agriculture.

The analysis of the genome of the Tyrolean Iceman, a 5,300 year old mummy from Central Europe, revealed a surprising recent common ancestry with modern Sardinians for this ancient genome. However, this study was limited both by the availability of data from Sardinians and by a lack of genomic data from other ancient European samples. Here, we use genomic data from modern Sardinians and from ancient European individuals from different geographic regions and cultural contexts, to demonstrate that this ancestry component is shared among individuals associated with the onset of agriculture in Europe. Our results thus suggest that the Iceman's Sardinian ancestry actually reflects a more widespread genetic component related to the migration of people during the Neolithic transition in Central Europe.

Sardinians genetic background explained by runs of homozygosity and genomic regions under positive selection

The peculiar position of Sardinia in the Mediterranean sea has rendered its population an interesting biogeographical isolate. The aim of this study was to investigate the genetic population structure, as well as to estimate Runs of Homozygosity and regions under positive selection, using about 1.2 million single nucleotide polymorphisms genotyped in 1077 Sardinian individuals. Using four different methods--fixation index, inflation factor, principal component analysis and ancestry estimation--we were able to highlight, as expected for a genetic isolate, the high internal homogeneity of the island. Sardinians showed a higher percentage of genome covered by RoHs>0.5 Mb (F(RoH%0.5)) when compared to peninsular Italians, with the only exception of the area surrounding Alghero. We furthermore identified 9 genomic regions showing signs of positive selection and, we re-captured many previously inferred signals. Other regions harbor novel candidate genes for positive selection, like TMEM252, or regions containing long non coding RNA. With the present study we confirmed the high genetic homogeneity of Sardinia that may be explained by the shared ancestry combined with the action of evolutionary forces.

Evidence for malaria selection of a CR1 haplotype in Sardinia

Complement receptor 1 (CR1) levels have been associated with malarial susceptibility and/or severity of the disease in different population groups, and CR1 is a receptor for Plasmodium falciparum. In this study, multiple CR1 single-nucleotide polymorphisms (SNPs) showed strong evidence of population differentiation between Sardinian and other European ethnic groups. Cross population algorithms comparing haplotype structure and differences in haplotype and allele frequency distribution provided additional support for natural selection of CR1 in Sardinia. The predominant Sardinian CR1 haplotype included SNPs that are associated with decreased CR1 levels in Europeans and other population groups. Previous studies have shown that the SNPs within the dominant Sardinian haplotype have a significantly higher frequency in a malaria endemic compared with non-endemic regions in India. Together with the historical evidence of the prevalence of malaria in Sardinia, these data support the role of malaria leading to positive selection of this CR1 haplotype in Sardinia.