Sikeliot
09-03-2018, 11:38 PM
Since we have new members, a lot of misconceptions are spreading around, I think it is worthwhile to go over the main points of the study again and I highlighted the important parts here with my own commentary.
https://www.nature.com/articles/s41598-017-01802-4
South Italy and the Aegean islands are genetically closer than either one to mainland Greece, are on a continuum with Cyprus, and have post-Neolithic admixture event with the Middle East:
Our results reveal a shared Mediterranean genetic continuity, extending from Sicily to Cyprus, where Southern Italian populations appear genetically closer to Greek-speaking islands than to continental Greece. Besides a predominant Neolithic background, we identify traces of Post-Neolithic Levantine- and Caucasus-related ancestries, compatible with maritime Bronze-Age migrations.
Mainland Greeks are genetically closest to Albanians, and with both intermediate between eastern Mediterranean islanders and Balkan Slavs:
In particular, Sicily and Southern Italy (SSI) appear as belonging to a wide and homogeneous genetic domain, which is shared by large portions of the present-day South-Eastern Euro-Mediterranean area, extending from Sicily to Cyprus, through Crete, Aegean-Dodecanese and Anatolian Greek Islands. We will refer to this domain as ‘Mediterranean genetic continuum’. On the other hand, the continental part of Greece, including Peloponnesus, appears as slightly differentiated, by clustering with the other Southern Balkan populations of Albania and Kosovo. Finally, North-Central Balkan groups (Southern Slavic-speakers and Romanians) show affinity to Eastern Europeans (Fig. 2, Supplementary Fig. S1, Supplementary Information).
All South Italians, Greeks, and Albanians share a common Neolithic Mediterranean base and around 24% Caucasus-related ancestry. The differentiation is caused by more recent admixture events involving additional Near Eastern is then present in South Italy and the Aegean islands, and additional Eastern European in Albania and Greece proper.
All populations from Southern Italy (SSI), Greece (both mainland and insular) and Southern Balkans share a predominant Sardinian (Neolithic-like) genetic component which accounts for more than half of their ancestry. This is followed by a relevant Caucasian-like ancestry, which is present at around 24% in all our population samples (Supplementary Fig. S2b). The other two major components instead show opposite patterns. The Near Eastern-like ancestry is more frequent in SSI and the Greek-speaking islands (i.e. the ‘Mediterranean continuum’), whereas increasing frequencies of the European-like component are observed in Albanians and mainland Greeks as well as in the rest of the Balkan Peninsula.
South Italians have half of the Steppe ancestry of mainland Greeks and Albanians:
Interestingly, Grecani of Calabria (GRI_BOV and GRI_CAL) and Cypriots share lower frequencies of the European-like ancestry (2.5% and 0.5%, respectively) compared to the other surrounding populations (Southern Italy: ~8%; Continental Greece and Albanians: ~15%).
Greeks and South Italians span 3 genetic clusters. Trapani is an outlier in Sicily, and is genetically more similar to Apulia, and some mainland Greeks are part of hat cluster. Despite being geographically in Sicily's west, Palermo and Agrigento are part of the main Sicily/Calabria cluster, along with most Aegean island Greeks. No mainland Greeks fall into the same cluster as Calabria, Messina, Catania, Palermo, Agrigento, Enna, or Ragusa.
FineSTRUCTURE results reconnect virtually all the individuals from Albanian and Kosovo, as well as the major part of individuals from mainland Greek populations, to a Southern-Balkan specific cluster (cyan in Fig. 3), which is almost completely absent in Greek-speaking islands and Southern Italy (except for Calabrian Arbereshe), instead showing relatively more similarity with Northern Italian populations (Supplementary Table S4). On the other hand, individuals from SSI, Crete and the Aegean/Dodecanese Greek Islands are mostly assigned to two other groups. The first one (CE-Sicily, limegreen in Fig. 3) is observed mainly in Central-Eastern Sicily and Calabria (excluding Calabrian Greeks), jointly with various Cretan and Anatolian/Dodecanese Greeks. The second one (AW-Sicily, purple in Fig. 3) encompasses individuals from the geographically opposed areas of Basilicata/Apulia (including Salentino Greeks) and Western Sicily (most notably Sicilian Arbereshe), as well as the remaining individuals from both continental and insular Greece. Importantly, these clusters appear tightly related with each other, showing some degree of admixture within a genetically continuous area.
Trapani and Apulia show evidence of recent admixture events with the Balkans:
Overall, patterns of IBD-relatedness suggest that ‘continuum’ populations (i.e. both Southern Italy and the Mediterranean Greek islands) share relatively more segments with the Caucasus and the Near East, while Albania and continental Greece appear significantly more related with Central and Northern Balkans, as well as Eastern Europe. Interestingly, despite showing much lower values of sharing, some Balkan IBD-relatedness also emerges in Greek-speaking islands as well as in Apulia and Western Sicily, presumptively reproducing some forms of interaction with Greece and the Balkans in the very recent ancestry of these areas, as consistently signalled by a common sharing of individuals in the FineSTRUCTURE AW-Sicily cluster (see also Supplementary Information).
No Balkan affinity is present in South Italian Griko people, but this does not rule out the possibility of Aegean islander input into that group:
Furthermore, we observed that both Calabrian and Apulian Greeks from Southern Italy almost completely lack the ‘Southern Balkan’ genetic component detected in Continental Greece and Albania, as well as in the Arbereshe. In both cases, this is consistent with the fact that their arrival in Southern Italy should at least predate those population processes associated to the more recent (i.e. late medieval) differentiation of continental Greek and Southern Balkan groups (cf. paragraph below). This does not exclude migrations from Aegean/Dodecanese and Crete islands, that presumptively did not (or only marginally) experienced - by virtue of their higher geographic marginality - the North-South Balkan gene flow that instead interested the continental part of Greece.
https://www.nature.com/articles/s41598-017-01802-4
South Italy and the Aegean islands are genetically closer than either one to mainland Greece, are on a continuum with Cyprus, and have post-Neolithic admixture event with the Middle East:
Our results reveal a shared Mediterranean genetic continuity, extending from Sicily to Cyprus, where Southern Italian populations appear genetically closer to Greek-speaking islands than to continental Greece. Besides a predominant Neolithic background, we identify traces of Post-Neolithic Levantine- and Caucasus-related ancestries, compatible with maritime Bronze-Age migrations.
Mainland Greeks are genetically closest to Albanians, and with both intermediate between eastern Mediterranean islanders and Balkan Slavs:
In particular, Sicily and Southern Italy (SSI) appear as belonging to a wide and homogeneous genetic domain, which is shared by large portions of the present-day South-Eastern Euro-Mediterranean area, extending from Sicily to Cyprus, through Crete, Aegean-Dodecanese and Anatolian Greek Islands. We will refer to this domain as ‘Mediterranean genetic continuum’. On the other hand, the continental part of Greece, including Peloponnesus, appears as slightly differentiated, by clustering with the other Southern Balkan populations of Albania and Kosovo. Finally, North-Central Balkan groups (Southern Slavic-speakers and Romanians) show affinity to Eastern Europeans (Fig. 2, Supplementary Fig. S1, Supplementary Information).
All South Italians, Greeks, and Albanians share a common Neolithic Mediterranean base and around 24% Caucasus-related ancestry. The differentiation is caused by more recent admixture events involving additional Near Eastern is then present in South Italy and the Aegean islands, and additional Eastern European in Albania and Greece proper.
All populations from Southern Italy (SSI), Greece (both mainland and insular) and Southern Balkans share a predominant Sardinian (Neolithic-like) genetic component which accounts for more than half of their ancestry. This is followed by a relevant Caucasian-like ancestry, which is present at around 24% in all our population samples (Supplementary Fig. S2b). The other two major components instead show opposite patterns. The Near Eastern-like ancestry is more frequent in SSI and the Greek-speaking islands (i.e. the ‘Mediterranean continuum’), whereas increasing frequencies of the European-like component are observed in Albanians and mainland Greeks as well as in the rest of the Balkan Peninsula.
South Italians have half of the Steppe ancestry of mainland Greeks and Albanians:
Interestingly, Grecani of Calabria (GRI_BOV and GRI_CAL) and Cypriots share lower frequencies of the European-like ancestry (2.5% and 0.5%, respectively) compared to the other surrounding populations (Southern Italy: ~8%; Continental Greece and Albanians: ~15%).
Greeks and South Italians span 3 genetic clusters. Trapani is an outlier in Sicily, and is genetically more similar to Apulia, and some mainland Greeks are part of hat cluster. Despite being geographically in Sicily's west, Palermo and Agrigento are part of the main Sicily/Calabria cluster, along with most Aegean island Greeks. No mainland Greeks fall into the same cluster as Calabria, Messina, Catania, Palermo, Agrigento, Enna, or Ragusa.
FineSTRUCTURE results reconnect virtually all the individuals from Albanian and Kosovo, as well as the major part of individuals from mainland Greek populations, to a Southern-Balkan specific cluster (cyan in Fig. 3), which is almost completely absent in Greek-speaking islands and Southern Italy (except for Calabrian Arbereshe), instead showing relatively more similarity with Northern Italian populations (Supplementary Table S4). On the other hand, individuals from SSI, Crete and the Aegean/Dodecanese Greek Islands are mostly assigned to two other groups. The first one (CE-Sicily, limegreen in Fig. 3) is observed mainly in Central-Eastern Sicily and Calabria (excluding Calabrian Greeks), jointly with various Cretan and Anatolian/Dodecanese Greeks. The second one (AW-Sicily, purple in Fig. 3) encompasses individuals from the geographically opposed areas of Basilicata/Apulia (including Salentino Greeks) and Western Sicily (most notably Sicilian Arbereshe), as well as the remaining individuals from both continental and insular Greece. Importantly, these clusters appear tightly related with each other, showing some degree of admixture within a genetically continuous area.
Trapani and Apulia show evidence of recent admixture events with the Balkans:
Overall, patterns of IBD-relatedness suggest that ‘continuum’ populations (i.e. both Southern Italy and the Mediterranean Greek islands) share relatively more segments with the Caucasus and the Near East, while Albania and continental Greece appear significantly more related with Central and Northern Balkans, as well as Eastern Europe. Interestingly, despite showing much lower values of sharing, some Balkan IBD-relatedness also emerges in Greek-speaking islands as well as in Apulia and Western Sicily, presumptively reproducing some forms of interaction with Greece and the Balkans in the very recent ancestry of these areas, as consistently signalled by a common sharing of individuals in the FineSTRUCTURE AW-Sicily cluster (see also Supplementary Information).
No Balkan affinity is present in South Italian Griko people, but this does not rule out the possibility of Aegean islander input into that group:
Furthermore, we observed that both Calabrian and Apulian Greeks from Southern Italy almost completely lack the ‘Southern Balkan’ genetic component detected in Continental Greece and Albania, as well as in the Arbereshe. In both cases, this is consistent with the fact that their arrival in Southern Italy should at least predate those population processes associated to the more recent (i.e. late medieval) differentiation of continental Greek and Southern Balkan groups (cf. paragraph below). This does not exclude migrations from Aegean/Dodecanese and Crete islands, that presumptively did not (or only marginally) experienced - by virtue of their higher geographic marginality - the North-South Balkan gene flow that instead interested the continental part of Greece.