::Yeah. All historic knowledge points to a predominance of Portuguese presence in the region, be it Azorean or lagunista. This is well supported by linguistic data: the region speaks Portuguese, and has spoken Portuguese from the 18th century, when this language superceded, not Castillian, but Guarani and other Amerindian languages. Andrea Rita Marrero's paper goes against this mainstream view and seems unsupported by any other sources. Moreover, when she discusses European vs Amerindian genetic ancestry, she gives details about what haplogroups support her findings, with tables, percents, and detailed discussion. When she discusses Portuguese vs Spanish genetic ancestry, there is nothing similar, just guesses and possibilities; no haplogroups are named and discussed, there are no tables, no percents, no verifiable discussion. 

 ::Indeed, I would like to know what haplogroups can be considered reliable markers of Spanish vs Portuguese ancestry; after all, the historic origin of both (Spanish and Portuguese) population is similar. The first actual noticeable separation between Portugal and Spain dates from 409-585 AD (the Swabian and Visigoth realms in the aftermath of the fall of the Roman Empire); but it is well know that both Swabians and Visigoths left smallish imprints in the demographic of the region. During the Reconquista, Portugal was indeed a feud of Castille up to 1139 (I wonder when this will be brought into discussion, to prove that all Brazilians - as well as all Portuguese - are of Spanish descent). Is there any user with actual knowledge in the field of genetics that can help us with that? 

 ::I suppose when you say that the "mtDNA of the Gaúchos surprised me, as it is lower than that of Argentina (which is 56%), and lower than that of the interior of Uruguay (about 60%)" you are refering to Amerindian MtDNA? Do you have cites for those figures? This would be very interesting.