It doesn't, no. I'm currently supervising 2 PhD students whose last name is alphabetically later than mine. I explained my reasons for my preference to them; t

It doesn't, no. I'm currently supervising 2 PhD students whose last name is alphabetically later than mine. I explained my reasons for my preference to them; that's how far I'll go. With one, we've had multiple collaborations outside the institution. In those cases, alphabetical order was typically arrived upon with all authors. In other cases it depends - we've had quite equal contribution papers which ended up alphabetically. We're now working on one that he conceived and executed. I'm basically the co-writing sparring partner, where I strongly prefer him to be first author. The other student feels it's important for his career to be first author, so he is. I certainly hope he's wrong (for my career so far it didn't matter), but I'm not taking that chance.