Negative range size–abundance relationships in Indo-Pacific bird communities

tropical areas and those in temperate zones. Hypotheses to explain positive range size–abundance relationships have focused on the ability of generalist species to appropriate resources, which allows them to simultaneously expand their ranges and dominate local communities (Brown 1984). The combination of geographic isolation with the high environmental stability of the tropics, however, may create conditions that reward narrow specialization in terms of resource and habitat use: long-term and annual climatic stability result in fairly constant environmental selection pressures, and at the same time low dispersal rates and community turnover mean that interspecific competition is relatively unchanging (Connell and Orians 1964, Fjeldså 1999, García-Moreno and Fjeldså 2000, Fjeldså et al. 2012). Positive relationships may then be absent where stable selection pressures favor species with strong local adaptations and concomitant small range sizes. The forests of non-land bridge tropical islands are ideal systems to test whether narrow specialization by species in geographically isolated and stable environments causes negative range size–abundance relationships. Tropical islands show remarkable long-term environmental stability because they rarely experience extreme weather events, are buffered against glacial cycles by marine currents, and have low Ecography 39: 990–997, 2016 doi: 10.1111/ecog.01622 © 2015 The Authors. Ecography © 2015 Nordic Society Oikos Subject Editor: Matthew Fitzpatrick. Editor-in-Chief: Miguel Araújo. Accepted 3 November 2015