ReggieM: I have not done any downstream clade analysis. My Ancestry update indicates Southern European 98% (89% Italian-South, 9% Greek) and I get a 2% Norwegian signal. So it may be possible that my IM223 Y-DNA is from a Scandanavian source, but I would not say that is definitive. Regardless, I identify ethnically as 1) of European descent, 2) Southern European, 3) Italian, and specifically Southern Italian_Sicilian. Period exclamation point, not to be flippant. So regardless of the the direct source of my Y-DNA Haplogroup, I still maintain IM223 is a WHG lineage that survived in different sub-clades in various regions of Europe. The 3 Mesolithic WHG in the ancient Roman study (Antonio et al 2019) all were I2, 1 IM436, the immediate upstream clade of IM223, and 2 were IM223. The WHG in Western Sicily (Grotto Uzzo) also have IM436 showing up. So I2 first appears a long time ago, and Y DNA I is likely the only indigenous Haplogroup that originated in Europe. So it could be these lineages just got absorbed into the local populations as they transitioned to farming societies and not really being tied to specific movements of people from one region to the other.
From the Antonio et al 2019 supplement:
Mesolithic (10,000-6,000 BCE; n=3)
All three Mesolithic individuals are assigned to the I-M436 (I2a2) haplogroup, with two of them further classified into the I-M223 (I2a2a) subclade. The I haplogroup has been found in western hunter-gatherer (WHG) populations from many parts in Europe, including individuals from the Grotte du Bichon in Switzerland (11,820-11,610 calBCE), France (11,140-10,880 calBCE), and Germany (7,460-7,040 calBCE)(15, 70). In particular, several Mesolithic hunter-gatherers from the Iron Gates between Serbia and Romania (dated to as old as 8,000 BCE) belonged to the specific I-M223 (I2a2a) haplogroup (14). Therefore, the I-M436 haplogroup appears typical and widespread in Europe before the Neolithic transition, which is consistent with the similarity of the three Mesolithic Italian individuals to other WHGs based on autosomal SNPs.