If you noticed the most mixed nation (by haplogroups) are romanians from Romania. Moldovans got two main haplos R1a and I (mostly I2a but also I1). At least 70% of moldovans are romanian-speaking. As I said romanians are the most mixed, granted to that we got a lot of surnames wich reflects nations' names as you can see below:
1. Rusu (the most spread) (Russian)
2. Ungurean(u) (Hungarian)
3. Sirbu (Serb)
4. Moldovan(u)
5. Grecu (Greek)
7. Bulgar(u) (Bulgarian)
8. Neamtu, Nemtanu (German)
9. Tintar(u) (Aromanian)
10. Vlah(u) (Vlach or Romanian from Walachia)
11. Ardeleanu (Transylvanian)
12. Arnaut(u) (Albanian)
13. Horvat (Croat)
14. Leahu (Pole)
I'm sure that Romanian nation emerged in the same way as American, Canadian or Australian and it happened when Latin (ancient Romanian) was the most spoken language
If you noticed the most mixed nation (by haplogroups) are romanians from Romania. Moldovans got two main haplos R1a and I (mostly I2a but also I1). At least 70% of moldovans are romanian-speaking. As I said romanians are the most mixed, granted to that we got a lot of surnames wich reflects nations' names as you can see below:
1. Rusu (the most spread) (Russian)
2. Ungurean(u) (Hungarian)
3. Sirbu (Serb)
4. Moldovan(u)
5. Grecu (Greek)
7. Bulgar(u) (Bulgarian)
8. Neamtu, Nemtanu (German)
9. Tintar(u) (Aromanian)
10. Vlah(u) (Vlach or Romanian from Walachia)
11. Ardeleanu (Transylvanian)
12. Arnaut(u) (Albanian)
13. Horvat (Croat)
14. Leahu (Pole)
I'm sure that Romanian nation emerged in the same way as American, Canadian or Australian and it happened when Latin (ancient Romanian) was the most spoken language
I agree that Romanians,as a whole, are pretty mixed people(genetically speaking,not ethnic),but definitely they are NOT THE MOST HETEROGENOUS.
After all, this is the place where Central Europe,Easten Europe and the Balkans met.
But you can find here diversity from ancient times: there are several distinct cultures in the Early Bronze Age which probably reflects distinct background.
http://www.eliznik.org.uk/EastEurope/History/history-pre.htm
Anthropology studies from The Bronze and Iron Age usually conclude: lack of homogenity.
http://iit.iit.tuiasi.ro/Reviste/mem_sc_st_2004/mss_series_IV_tome_XXVII_2004_p245.pdf
Roman colonization and Migration Period also played a role here.
But, there are quite homogenous areas(not few,not small) ,some of them from pre-Roman Age,most notably:MARAMURES,OAS,,APUSENI/TARA MOTILOR,BUCOVINA.
http://en.wikipedia.org/wiki/Carpathian_Tumuli
From those you mentioned:Grecu,Bulgaru,Tintaru,Arnautu,Leahu- are very rare.
Horvat is a Hungarian name -bearers could be Magyars from Transylvania,Magyarized Romanians or Csango.
Rus/Rusu -does not come from "Russian",but Latin "russus"-red,reddish
http://en.wiktionary.org/wiki/russus
http://dexonline.ro/definitie/rus
Check out the Italian surnames:
ROSSO, ROSSA,ROSSI, RUSSI, RUSSO, RUGGIU, RUBIU, ROSSELLI, ROSSELLO, ROSSELLINI, RISSIELLO, ROSSILLO, ROSSETTI, ROSSETTO, ROSSETTINI, ROSSITTI, ROSSITTO, ROSSINI, ROSSINO, ROSSOTTI, ROSSOTTO, ROSSINI, ROSSONE, ROSSUTO, RUSSELLO, RUSSINO, RUSSOTTI, RUSSOTTO, RUSSIANI, RUSSOLILLO.
Ungureanu- Romanians from Transylvania were called this way by the Moldavians and Wallachians; it has nothing to do with Hungarians.
Arnautu-initially meant Albanian mercenary guard ,but the latter sense is "armed servant".
http://dexonline.ro/definitie/arnăut
Neamtu, Nemteanu means inhabitant(Romanian) of Neamt region.
The same with Moldovan/Moldoveanu,Ardelean/Ungureanu,as for Vlah- it's not a frequently used name, Romanians didn't call themselves that way.