Uniparental markers in Italy reveal a sex-biased genetic structure and different historical strata

University of Adelaide Genographic Consortium contributers: Christina J. Adler, Alan Cooper, Clio S. I. Der Sarkissian, Wolfgang Haak.Located in the center of the Mediterranean landscape and with an extensive coastal line, the territory of what is today Italy has played an important role in the history of human settlements and movements of Southern Europe and the Mediterranean Basin. Populated since Paleolithic times, the complexity of human movements during the Neolithic, the Metal Ages and the most recent history of the two last millennia (involving the overlapping of different cultural and demic strata) has shaped the pattern of the modern Italian genetic structure. With the aim of disentangling this pattern and understanding which processes more importantly shaped the distribution of diversity, we have analyzed the uniparentally-inherited markers in ~900 individuals from an extensive sampling across the Italian peninsula, Sardinia and Sicily. Spatial PCAs and DAPCs revealed a sex-biased pattern indicating different demographic histories for males and females. Besides the genetic outlier position of Sardinians, a North West–South East Y-chromosome structure is found in continental Italy. Such structure is in agreement with recent archeological syntheses indicating two independent and parallel processes of Neolithisation. In addition, date estimates pinpoint the importance of the cultural and demographic events during the late Neolithic and Metal Ages. On the other hand, mitochondrial diversity is distributed more homogeneously in agreement with older population events that might be related to the presence of an Italian Refugium during the last glacial period in Europe.Alessio Boattini, Begoña Martinez-Cruz, Stefania Sarno, Christine Harmant, Antonella Useli, Paula Sanz, Daniele Yang-Yao, Jeremy Manry, Graziella Ciani, Donata Luiselli, Lluis Quintana- Murci, David Comas, Davide Pettener, the Genographic Consortiu

Changes in the genetic structure of a valley in the Pyrenees Catalonia (Spain)

In some situations the use of isonymy is the best strategy for studying the genetic structure of a population and its biological history. In this study different population parameters were calculated for one of the most isolated valleys in the Pyrenees – the region of the Alta Ribagorça in Catalonia, Spain. Surnames from marriage records covering the continuous period from 1638 to 1988 were used. From 1950 onwards this region underwent important social, economic and biological changes related to the introduction of hydroelectric and mining industries, and the change from livestock farming to a society based on services. Two periods were analysed (1638–1950 and 1951–1988) allowing population changes that occurred in the region to be determined. The study focused on calculating the number of surnames by gender, diversity index (H), population sub-structure (RP − RPr)/ RPr and inbreeding coefficient (Ft) and detection of possible genetic barriers. The results demonstrate the importance that geography initially had in shaping the genetic structure of the population and how this was gradually replaced by other parameters such as roads or the social and economic importance of towns. An interesting phenomenon is that inbreeding has traditionally been associated with rural life, isolation and endogamy. However, for the Alta Ribagorça it was observed that in the second period, 1951–1988, inbreeding mainly depended on the composition of migrant groups and the reaction of the native population to the arrival of migrants from outside the region

Uniparental markers in Italy reveal a sex-biased genetic structure and different historical strata

Located in the center of the Mediterranean landscape and with an extensive coastal line, the territory of what is today Italy has played an important role in the history of human settlements and movements of Southern Europe and the Mediterranean Basin. Populated since Paleolithic times, the complexity of human movements during the Neolithic, the Metal Ages and the most recent history of the two last millennia (involving the overlapping of different cultural and demic strata) has shaped the pattern of the modern Italian genetic structure. With the aim of disentangling this pattern and understanding which processes more importantly shaped the distribution of diversity, we have analyzed the uniparentally-inherited markers in 900 individuals from an extensive sampling across the Italian peninsula, Sardinia and Sicily. Spatial PCAs and DAPCs revealed a sex-biased pattern indicating different demographic histories for males and females. Besides the genetic outlier position of Sardinians, a North West–South East Y-chromosome structure is found in continental Italy. Such structure is in agreement with recent archeological syntheses indicating two independent and parallel processes of Neolithisation. In addition, date estimates pinpoint the importance of the cultural and demographic events during the late Neolithic and Metal Ages. On the other hand, mitochondrial diversity is distributed more homogeneously in agreement with older population events that might be related to the presence of an Italian Refugium during the last glacial period in EuropeThis study was supported by Strategic Project 2006-09 from the University of Bologna to DP and from MIUR PRIN 2007 and 2009 Grants to DP. The project was also supported by the Spanish Government grant CGL2010-14944/BO

Gut microbiota composition in Himalayan and Andean populations and its relationship with diet, lifestyle and adaptation to the high-altitude environment

Human populations living at high altitude evolved a number of biological adjustments to cope with a challenging environment characterised especially by reduced oxygen availability and limited nutritional resources. This condition may also affect their gut microbiota composition. Here, we explored the impact of exposure to such selective pressures on human gut microbiota by considering different ethnic groups living at variable degrees of altitude: the high-altitude Sherpa and low-altitude Tamang populations from Nepal, the high-altitude Aymara population from Bolivia, as well as a low-altitude cohort of European ancestry, used as control. We thus observed microbial profiles common to the Sherpa and Aymara, but absent in the low-altitude cohorts, which may contribute to the achievement of adaptation to high-altitude lifestyle and nutritional conditions. The collected evidences suggest that microbial signatures associated to these rural populations may enhance metabolic functions able to supply essential compounds useful for the host to cope with high altitude-related physiological changes and energy demand. Therefore, these results add another valuable piece of the puzzle to the understanding of the beneficial effects of symbiosis between microbes and their human host even from an evolutionary perspective

Spatial Principal Component Analysis (sPCA) based on frequencies of Y-chromosome haplogroups.

<p>The first two global components, sPC1 (a) and sPC2 (b), are depicted. Positive values are represented by black square; negative values are represented by white squares; the size of the square is proportional to the absolute value of sPC scores.</p

Discriminant Analysis of Principal Components (DAPC) for G2a-P15 haplotypes.

<p>Samples are grouped according to their affiliation at the sPCA-identified groups (NWI; SEI; SAR; symbols in the top right table). The table in the bottom left shows the number of haplotypes in each of the five G2a clusters and their geographical distribution in the three Italian areas. DAPC eigenvalues are depicted in the enclosed barplot.</p

Age estimates (in YBP) of STR and HVS variation for the most common haplogroups in the Italian data set.

<p>Standard deviation (SD) estimator (Sengupta et al. 2006) and ñ statistic calculator (Soares et al. 2009) were used for Y-chromosome and mtDNA haplogroups respectively. Ages were estimated for the entire haplogroups as well as for each DAPC cluster with at least 10 individuals and frequencies >70% in NWI, SEI, or SAR (excepted for G-P15, cluster 2, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065441#s2" target="_blank">Methods</a>).</p

POPULATION GENETICS. Genomic evidence for the Pleistocene and recent population history of Native Americans.

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model

Genomic evidence for the Pleistocene and recent population history of Native Americans

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model