An understanding of participation dynamics within online production communities requires an examination of the roles assumed by participants. Recent studies have established that the organizational structure of such communities is not flat; rather, participants can take on a variety of well-defined functional roles. What is the nature of functional roles? How have they evolved? And how do participants assume these functions? Prior studies focused primarily on participants' activities, rather than functional roles. Further, extant conceptualizations of role transitions in production communities, such as the Reader to Leader framework, emphasize a single dimension: organizational power, overlooking distinctions between functions. In contrast, in this paper we empirically study the nature and structure of functional roles within Wikipedia, seeking to validate existing theoretical frameworks. The analysis sheds new light on the nature of functional roles, revealing the intricate "career paths" resulting from participants' role transitions.