Large scientific collaborations or teams are becoming more common in astronomy and present particular opportunities and challenges for diversity. They have been the norm in some areas of physics, such as particle physics, for years and can be as large as 1000's of members. Sizes in astronomy are more typically 100's, although larger teams are on the horizon.
The special attributes of a large collaboration that can affect diversity include election or appointment of collaborations leaders, organization of sub-teams, collaboration meetings with large numbers of attendees, papers with large numbers of authors, and presentations at conferences decided by committees. In the context of the Committee for the Status of Women in Astronomy, I will concentrate here on issues for women. I was motivated to write this piece by an excellent discussion of such diversity issues at a recent LIGO-Virgo collaboration meeting.
Even if the fraction of women in a collaboration is not much different from the fraction in astronomy / astrophysics in general, the representation in leadership positions is often lower. This can be due to the female fraction being younger on average than the more senior members who are largely male. Another factor can be the way the positions are chosen, either by election or appointment, that may favor previous leaders. When unbalance exists, it ca be hard to change.
On the other hand, there is opportunity here and large collaborations can provide a means for advancement of women and other under-represented groups. Since there are many members, there are also a good number of leadership positions. These include the collaboration executives and leaders of the sub-teams. If an effort is made to be conscientious in recruiting among the qualified women for top positions, they can be highly visible and provide motivation examples for young people. A snow-ball effect an occur that produces a growing representation. Particularly motivating is when the accomplishments of a successful woman are recognized by a leadership position. Below are pictures of a few notable examples.
In large collaboration meetings, a male-dominated dynamic can make it even more intimidating for women to speak up. There may be confrontational debates and win-lose discussions. It is important that the roles of interaction in the collaboration allow for all voices to be heard, different styles of interaction be recognized, and that the "volume" of the discussions be lowered.
Without attention to different styles of leadership, women can be squeezed out of key roles in the generation of papers and selection for conference talks. The same pressure can occur as in the selection of collaboration leaders, namely that team dynamics and historical patterns may make if hard for women to break in. Once again, the rules of the collaboration can be adjusted to make sure that all members can compete based on their accomplishments and abilities in these important activities.
Here are some ways to increase the diversity in all these areas: (1) significant representation of accomplished women in advisory and decision-making groups, not just service positions, (2) more rapid turn-over of leadership positions, and (3) establishment of diversity advocates within the collaboration to help nudge the system along. Perhaps you have other suggestions.