>>212928912
there's a 2009 study that said Paswans/Dusadhs in Bihar are ~40% R1a. I don't know if that's a founder effect or something else. Might've been from small sample size too, I'll have to check.
>Caste groups in India converge around different genetic haplogrpups.
Somewhat, but there are great differences from region to region too. West Bengal Brahmins have around 70% R1a which is proportionally twice as high as Punjabi Brahmins at 35%.