The essential currency of the modern biomedical science career is the research publication. By which I mean your name listed as an author on a peer-reviewed journal article. This has always been the case and is not selective to science, the publish-or-perish mantra is common to many academic disciplines.
Nevertheless. In bioscience the current realities of career, funding and advancement put a huge pressure on scientists to accumulate as many authorship credits as possible.
Which means you must ignore conventional or traditional concepts of how things are done, what is polite behavior, whether you are being a selfish snot, etc and discuss authorship early, often and continually with your labmates, mentors, collaborators and trainees.
MsPhD has a post up over on YoungFemaleScientist in which she ponders some of the issues:
...I noticed something interesting: despite having no new first-author publications, MrPhD has now surpassed me in the grand total of publications, because he has more papers on which he is a middle author.
For almost every project in his lab that he has contributed to, MrPhD was made an author. He says they usually tell him up front that he'll be an author.
I, on the other hand, have learned to ask, or risk wasting my time, when I should be working on my own projects. This is true regardless of whose lab wants my help (my own or someone else's).
I am often told I'm being greedy when I ask up front whether I'll be an author.
YHN has the back of just about anyone who wants to discuss authorship in a legitimate and collegial fashion. When someone tells you that you are being too demanding or otherwise socially awkward for bringing up authorship, I am very suspicious that they are trying to hose you for their own interests. Nobody should be embarrassed to discuss authorship in collaborations or long-term mentoring associations. It is just too important. And I feel quite strongly that a little discussion along the way can to a LOOOOONNNNG way to heading off the furor of authorship nastiness that has been known to accompany manuscript submission.
Make no mistake. I should make myself quite clear that people need to be engaged in the authorship discussion in a professional and legitimate manner. This is not permission to grub for authorships that you do not deserve, not to alter my stance that ultimately the PI decides authorship disputes. Above all, you must be aware that you do not necessarily deserve authorship on any basis other than what the eventual manuscript has become. Not for "ownership" of a technique or domain, not for length of time served, not for amount of "effort" expended.
All I am saying is that it is a legitimate and helpful behavior to have discussions about how particular experiments, lines of experiments, collaborations, etc may contribute to an eventual paper in an ongoing and open manner.
These ongoing discussions within lab can, perhaps, help with intra-lab competition. Admittedly, no amount of discussion can overcome a legitimate lab-cancer person who permeates every interaction with selfishness. Nevertheless, if people are feeling a little miffed about always contributing to someone else's first author publication as a middle author it is important to discuss how/when s/he will likely get their own first author manuscript together including which of the aforementioned other lab members will be contributing. Worrying about publishing is a legitimate, but time and motivation sapping, tradition of the training process. Charting a path to each trainees' eventual manuscript submission can go a long (and painless/cost free) ways towards improving morale.
The mentor / PI should always be attentive to the authorship needs of each trainee's career whilst s/he is pumping out the best papers possible from the group as a whole. However, things can get lost in the shuffle. So it is important to have those conversations, even if trainees need to work up the courage to say "So, PI, I'd really like to attain a first author paper, here's what I've been doing and I think we need to refocus a bit on my paper now".