Ecology's dark matter: The elusive and enigmatic niche

Ecologists are often frustrated that their universe, populated by strange and wilful creatures, seems fuzzy and unpredictable. Physicists, in contrast, seem to have it much better. But that's because we usually focus on Newtonian physics. In fact, physicists seem happy to live with all kinds of strange beasts, including dark matter, something they have never seen, but which they nevertheless believe makes up most of the matter in the universe. Here I argue that niches are ecology's dark matter. We are embarrassed by them, because we do not quite know what they are, and yet their presence can be universally felt; otherwise, ecological communities, like galaxies without dark matter, would simply collapse. I describe how we could potentially better describe these dark shapes that haunt our science and why this is important. In particular, I present the outline of a method for demonstrating whether or not plant species have complementary resource-use niches; something that has been difficult to show unequivocally. The presence of such resource-use niches would put to rest once and for all the notion of species equivalence and the neutral world that this assumption entails. I conclude that ecologists should take a leaf out of the physicists' book and accept that the continued search for the esoteric niche is a legitimate and central (if frustrating) part of ecology. © 2013 Gesellschaft für Ökologie.