To account for this variations one needs to understand this history of the Roman Empire and their slave trade.
The question: Where the slaves come from? (to supply over a million+ slaves to Rome, there is this article : The Roman slave supply, Walter Scheidel, Princeton and Stanford University 2007. PDF, page 13.., they were from; the Iberian peninsula, the southern Balkans, North Africa, Western Anatolia, Gaul, the Levant, Britain, Germany,, Parthia ,. "Roman merchants bartered Italian wine for CELTIC chattels.etc, etc etc."
Quote: "Roman law required dealers (in slavery) to disclose the ethinic origin of slaves."
Find article Yahoo or Google: The roman slave trade. www. princeton.edu etc.
All the above pictures clearly show the diversity of people that no doubt may be descendants of the million+ slaves of 2000 brought to Italy.
One has to consider the population of Rome prior to 2000 years ago to see the reality of the different haplogroups found in Italy today infused by the slave trade.
Consider also that most likely the vast majority of slaves were MALE, since they were needed for the workforce. And males do pro-create and spread their Y-DNA!!! Fast forward 2000 years and voila! Haplogroups tested in Italy, are: R1b, R1a, J1, J2, G, E3b, I etc., etc, .
