  Studies over the past decade demonstrated that developers contributing to
open source software systems tend to self-organize in "emerging" communities.
This latent community structure has a significant impact on software quality.
While several approaches address the analysis of developer interaction
networks, the question of whether these emerging communities align with the
developer teams working on various subsystems remains unanswered. Work on
socio-technical congruence implies that people that work on the same task or
artifact need to coordinate and thus communicate, potentially forming stronger
interaction ties. Our empirical study of 10 open source projects revealed that
developer communities change considerably across a project's lifetime (hence
implying that relevant relations between developers change) and that their
alignment with subsystem developer teams is mostly low. However, subsystems
teams tend to remain more stable. These insights are useful for practitioners
and researchers to better understand developer interaction structure of open
source systems.
