Haplogroup I1 is a marker of Germanic migrations to Italy. The Ostrogoths, Vandals, Lombards, Franks and Normans all left some I1 lineages behind them. The distribution of I1 is fairly homogeneous all over Italy, usually ranging from 1 to 5%. I had a look at the new study by Boattini et al. to see if hotspots could be identified. Let's also note that this is the first Italy-wide study that tests other I subclades than I2a1a (M26, former I1b2), and the first to confirm I1 percentages at a provincial level.

The first surprise came in Vicenza, where 17.5% of the male lineages belonged to I1, a proportion rarely seen outside Scandinavia or northern Germany. The other surprise were the 10.5% in Bologna.

Campobasso (14%) is the third hotspot, but that one was expected, as the city was founded by the Lombards, a tribe that originated in southern Sweden.

It's interesting to compare Campobasso, a Lombard city, with L'Aquila, a city founded in the 13th century by the Germans (mostly Swabians). While half of Campobasso's Germanic lineages are I1 (the rest being R1b-U106 and I2b1), L'Aquila completely lacks I1. Its Germanic lineages are one I2b1, one R1a, and one R1b-U106. This looks much more southwest German indeed. There is surely some I1, but the proportion within German lineages shouldnt exceed 10-15% if settlers came from southern Germany.

Apart from that, the frequencies observed were always within the expected range. I1 was completely absent from Sardinia and Catania, as in past studies.

North Italy

InCuneo, south-west Piedmont, 1 out of 30 samples are I1 (3.5%).

InSavona/Genova, central Liguria, 2 out of 50 samples are I1 (4%).

InComo, north-west Lombardy, 1 out of 41 samples are I1 (2.5%).

InBrescia, north-east Lombardy, 1 out of 39 samples are I1 (2.5%).

InVicenza, central-west Veneto, 7 out of 40 samples are I1 (17.5%).

InTreviso, central-east Veneto, 1 out of 30 samples are I1 (3.5%).

InBologna, central Emilia-Romagna, 3 out of 29 samples I1 (10.5%).

Central Italy

InLa Spezia-Massa, north-west Tuscany, 1 out of 24 samples are I1 (4%).

InPistoia, central-north Tuscany, 0 out of 13 samples are I1 (0%).

InGrosetto-Siena, southern Tuscany, 4 out of 86 samples are I1 (4.5%).

InFoligno, central-east Umbria, 1 out of 37 samples are I1 (2.5%).

InMacerata, central-east Marche, 0 out of 40 samples are I1 (0%).

South Italy

InL'Aquila, Abruzzo, 0 out of 23 samples are I1 (0%).

InCampobasso, Molise, 4 out of 29 samples are I1 (14%).

InBenevento, Campania, 1 out of 36 samples is I1 (2.5%).

InMatera, Basilicata, 0 samples out of 25 are I1 (0%).

InLecce, Apulia, 1 out of 39 samples is I1 (2.5%).

InCosenza/Catanzaro/Crotone, Calabria, 1 out of 38 samples is I1 (2.5%).

InCatania, eastern Sicily, 0 out of 62 samples is I1 (0%).

InRagusa, southeast Sicily, 1 out of 44 samples is I1 (2%).

InAgrigento, southwest Sicily, 1 out of 42 samples is I1 (2.5%)

InOlbia/Tempio/Nuoro, north-east Sardinia, 0 out of 40 samples is I1 (0%).

InOristano, central-west Sardinia, 0 out of 42 samples are I1 (0%).

EDIT : I have added the hotspots on the I1 map.