I'm a graduate student in theoretical particle physics, where the standard is that all author lists are alphabetized. However, even in other disciplines of physics, it's quite common for author lists to be ordered by the amount of the contribution. At some point I will probably be judged by people who are not entirely familiar with the standards of particle theory, and even if they are they probably have subconscious biases towards earlier authors.
I also happen to have a last name that's around the middle of the alphabet. I can feasibly find an advisor whose name is after mine, but the most natural choices (including my current advisor) all happen to be before mine alphabetically. My current choice makes me a bit worried because most of his other students also have names before mine alphabetically. I'll probably have a number of publications with other people in the group, and it's not unlikely that I'll be the last author on most or all of these.
Is this something that I should be seriously worried about? (My heart tells me no, but my brain isn't sure.) Will I have much more trouble in the future than comparable candidates who are listed earlier? Or is it a fairly small effect which is much less significant than choosing a good advisor in the long term?