Czy skandynawska ludność z I1 mieszała się z posiadaczami I2, czy raczej tworzyli osobne grupy?

(...) Consequently, the plague that stalked populations for much of the Bronze Age must have been pneumonic, which directly affects the respiratory system and causes desperate, hacking coughing fits just before death. Breathing around infected people leads to inhalation of the bacteria, the crux of its human-to-human transmission.

Study co-author Dr Marta Mirazón-Lahr, from Cambridge's Leverhulme Centre for Human Evolutionary Studies (LCHES), points out that a study earlier this year from Willerslev's Copenhagen group showed the Bronze Age to be a highly active migratory period, which could have led to the spread of pneumonic plague.

"The Bronze Age was a period of major metal weapon production, and it is thought increased warfare, which is compatible with emerging evidence of large population movements at the time. If pneumonic plague was carried as part of these migrations, it would have had devastating effects on small groups they encountered (...) Well-documented cases have shown the pneumonic plague's chain of infection can go from a single hunter or herder to ravaging an entire community in two to three days." (...)

A wiesz może jak wyglądała sytuacja po przybyciu R1a i później R1b? Czy te grupy się mieszały

in Western Europe, related lineages within R1b-L11 expanded ~4.8–5.9 kya (Supplementary Fig. 14e), most markedly around 4.8 and 5.5 kya. The earlier of these times, 5.5 kya, is associated with the origin of the Bronze Age Yamnaya culture. The Yamnaya have been linked by aDNA evidence to a massive migration from the Eurasian Steppe, which may have replaced much of the previous European population24,25; however, the six Yamnaya with informative genotypes did not bear lineages descending from or ancestral to R1b-L11, so a Y-chromosome connection has not been established. The later time, 4.8 kya, coincides with the origins of the Corded Ware (Battle Axe) culture in Eastern Europe and the Bell–Beaker culture in Western Europe26.

We can say R1b-M269 is more likely [for ATP3 individual] than the others because the others have contradictory calls - in most cases lots of contradictory calls.

E1b1b1a1-L547+, but E1b1b1a-PF2108-, E1b1b-PF1689-, E1b1-P180-, E-PF1561- (besides it is F+)
I2a2a1b2a2-something-Y16447+ (not old enough anyway according to Y-Full), but I-CTS1006-, IJ-F1450, IJ-Y1943-
J2a1b-S18476+, but J2a-M410-, J2-PF4926-, J-PF4562-, and the 2 IJ-
O3a2c1c1-F1835+, but NO-F415-, NO-M2335-
Q1b-Y1109+, but Q1b-Y1254- (to be fair this might not be equivalent)
Q1a2b2a2-Y1618+, but Q1a2-Y750-
R2(a?)-Y3545+, but R2(a?)-Y3385-, Y3402-, FGC22606-, Y4689-, FGC12636-
R1b1a2-PF6518+, R1b1a-Y97+ (albeit this one is likely spurious), R1-M748+, K-PF5501+, GHIJK-M3773 , F-Y1811+, F-PF2756+.

If it is actually R1b-M269 then it has 6 contradictory calls scattered randomly through a very large number of called SNPs (and these could even be genuine private SNPs for all we know), and a neat unbroken sequence of positive SNPs.
If it was another one then there are more contradictory calls, including negative SNPs upstream in their own lineages, and the R ones just happen to form an unbroken sequence.
So M269 *is* more likely than any of the others, due to that crazy little thing called math.

It could still be just a fluke, or more plausibly contamination (though from what Ted Kandell was saying the R1 SNP sounds genuine). I wouldn't take it as solid proof of early Iberian M269. But I certainly wouldn't bet against finding more either.

ATP3 (3516–3362 BCE) stands out from other samples thanks to its high Northern Middle Eastern ancestry (31.97%) against 0% for ATP20, 11% for ATP17 and between 0% and 8% for other samples. What Genetiker calls Northern Middle Eastern is what we typically referred on this forum as Caucaso-Gedrosian admixture - the same as in the "Armenian-like admixture" in Yamna samples.

With its 32% of Caucaso-Gedrosian, 14% of Northern European ancestry, 6% of European Hunter-Gatherer and 3.8% of Veddoid, it does indeed look as if ATP3 has a bit over half of Steppe ancestry, but with a higher proportion of northern Middle Eastern and Veddoid than Yamna samples. In other words it could be descended to the pre-Indo-European Anatolian R1b-M269, the group of cattle herders that would cross the Caucasus and settle in the Pontic-Caspian Steppe. So could it be an offshoot of cattle herders that directly migrated from Anatolia to Iberia during the Neolithic period.

od kiedy można przypuszczać zatarcie się odrębności i mieszanie się składników (R1a, R1b, I), które później dadzą początek Germanom?

Ja wywodzę Germanów tylko od rzeczy które są "nordic".

Villabruna (Sovramonte – Belluno, Italy)
The burial of Riparo Villabruna was discovered in 1988 by A. Broglio in the small
rockshelter named Riparo Villabruna A in the Veneto Dolomites. It contains a partial
skeleton with lower limbs severed at the distal femoral shafts associated with burial goods of
the Epigravettian culture50. The date quoted here comes from the skull51, whereas the genetic
analysis is of a left femur. This individual bears the earlier known example of treatment of
dental caries52.

• Villabruna at 14,180-13,780 cal BP (KIA-27004: 12,140±7014C)51
(direct date, using collagen ultrafiltration)

[...]

We were surprised to assign Villabruna to R1b1 (Table S4.2). When we restrict to damaged sequences, we still assign it to R1b

[...]

Based on analysis of statistic like D(X, Y; Villabruna Cluster, Mbuti), we find that
BerryAuBac, Bichon, Bockstein, Chaudardes1, Falkenstein, Ranchot88, Rochedane, and
Villabruna all show a high degree of allele sharing with Mesolithic Western Europeans
including Loschbour and LaBrana1, which are sometimes also called “Western Hunter
Gatherers”4 (Table S5.6). We view all these samples as closely related, along with
Hungarian.KO1 which clusters with them despite being from an Early Neolithic context6.

Nice! Definitely M343, likely L278.
And in Italy!!

Fact of the matter is; that the oldest R1b1 found to date is not from Eastern Europe but from a full fledge WHG who appears to be the very first WHG in Europe. Thus it seems that the entrance of R1b1 into Europe from the east obviously is dated back to this input of Caucasian-like population dating back to 14000 ybp.BTW very first Haplogroup I in Europe also dated back to 31-34 kya from Italy of all places. So it seems the entrance of Hg I in Europe is Gravettian.

Pierwsi R1b wkroczyli do Europy co najmniej 14,000 lat temu, ale skąd?

Otóż okazuje się, że z Bliskiego Wschodu (jak wskazuje DNA autosomalne).

Czyli mamy migrację z łowców-zbieraczy z Bliskiego Wschodu do Italii