The purpose of this study is to investigate interaction between collaborators within individual studies by measuring how they made contributions to their studies. Author contribution network is constructed based on the author contribution statements of 140,000 full-text articles in PloS by viewing every collaborator as a node and a shared contribution as an edge. Three types of contributors are identified: general team-players, factotums, and mavericks. The preliminary result suggests that division of labor widely exists in scientific re-search and the latter two types of collaborators are common in small teams
