Do persistent rare species experience stronger negative frequency dependence than common species?

Understanding why so many species are rare yet persistent remains a significant challenge for both theoretical and empirical ecologists. Yenni et al. (2012, Ecology, 93, 456-461) proposed that strong negative frequency dependence causes species to be rare while simultaneously buffering them against extinction. This hypothesis predicts that, on average, rare species should experience stronger negative frequency dependence than common species. However, it is unknown if ecological communities generally show this theoretical pattern. We discuss the implications of this phenomenon for community dynamics, and develop a method to test for a non-random relationship between negative frequency dependence and relative abundance using species abundance data from 90 communities across a broad range of environments and taxonomic groups. To account for biases introduced by measurement error, we compared the observed correlation between species relative abundance and the strength of frequency dependence against expectations from a randomization procedure. In approximately half of the analysed communities, we found increasingly strong negative frequency dependence with decreasing relative abundance: rare species experienced stronger frequency dependence than common species. The randomization test never detected stronger negative frequency dependence in more common species. Our results suggest that strong negative frequency dependence is a signature of persistent, rare species in many communities.