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Gannicus, Dacians might have had their share of I2a and R1a (which remains to be proved by ancient samples) but I believe that there are a few objections to your hypothesis.
Romanians and moldovans have so much I2a and R1a, wich are of the same clades as those found among albanians:
Why couldn't them be dacian?
First of all, it would be necessary to specify the similar clades between Romanians/Moldavians and Albanians ? This would certainly help the discussion because comparing at I2a/R1a level is not very meaningful.
I am not an expert on Romanian/Moldavian genetics and a scientific paper would certainly help. What I can say on the similiarity argument (for R1a) concerns my own clade and it is not present in Romania/Moldova. It is pretty much the same for its parent branch R-Y2902 which has only scarce presence in Romania/Moldova (0,52% of the samples in FTDNA and only a couple of predicted lineages in the R-Y1392 project of FTDNA ). In view of this I would say that the similarity is limited and that if the Romanian/Moldavian territories where the place of origin of R-Y2902, I would expect to find more presence and diversity there.
It doesn't make any sense that romanians are mostly slavic, and now speak romanian.
We know very well how hard it is to assimilate slavs and how easly they assimilated other cultures, so it doesn't make much sense that I2a-M423 and R1a (forgot the clade) are slavic.
There are known cases where language and genetics do not correspond. I am not an expert in linguistics but there is also slavic influence in the romanian language. For instance, their word for yes is "da". In short, I do not think that this is a solid argument.
It makes sense tho, that:
1) Ostrogoths have it as dacians lived in parts of hungary too, like in Avar Szolad, and assimilated them there, and from there spread them everywere they went.
First, an Avar sample is not Dacian (at least to my knowledge). Besides, it is debated whether that "avar" sample (SZ1-R1a Z93) is really from the migration period or a bronze age sample (in short, it was not labelled as such in the scientific paper, it seemed to be an ancestor to other (older) samples and it did not match with the two other avar samples found there). But more important, there was not massive Ostrogothic come back to Southern Balkans (neither to Romania / Bulgaria) after settling in Pannonia. Whatever R1a/I2a lineages the Goths might have brought to the Balkans, I think that they would have assimilated them before settling to Pannonia, i.e. during their migration from Scandinavia to the Black Sea and then to the Dabube. That being said, it is true that the Goths formed a polyethnic confederation. In his History of the Goths, Herwig Wolfram mentions that their community comprised Finns, Slavs, Antes, Heruli, Alans, Huns, Taifali, Sarmatians, Aesti, Bastarnae and Romanized Daco-Carpian groups.
2) Jugoslavs have them as they could have assimilated many carpathian people/dacians, and then brought them to the balkans. Now, albanians could have them from slavs or ostrogoths, but in both cases, if what I suggest is true, it would be true.
If the South Slavs assimilated those lineages during their migration to the Balkans they would logically be absent in common Slavs. Then arises the question of knowing who brought them to the North (Poland, Baltic, etc.) and to the East (Russia) ? Finally, what would be the original South Slavic lineages then ? As you might know, R1a and I2a are major haplogroups among Croats, Bosnians and Serbs (at least in terms of frequency).
And what if dacians directly brought it to albania? What would you think about albanians being of dacian origin and R1a + I2a originally?
I have no knowledge of a recorded Dacian migration to Illyricum/Albania. Be it as it may, ancient samples and current figures (frequencies, TMRCAs and diversity) do not support your hypothesis. Today, R1a and I2a are a minority among modern Albanian lineages. If they were to be the "original" Albanians, then why did they shrink and which people brought the dominant haplogroups between Albanians (E-V13, R-Z2103 and J-L283), and the Albanian language in the Northern mountains of Albania which are barely accessible ?