Challenges in the application of geometric constraint models |
| |
Authors: | Craig R McClain Ethan P White Allen H Hurlbert |
| |
Institution: | Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, USA,;Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA,;Department of Biology, Utah State University, Logan, UT 84322, USA and;National Center for Ecological Analysis and Synthesis 735 State Street, Suite 300, Santa Barbara, CA 93101, USA |
| |
Abstract: | Discerning the processes influencing geographical patterns of species richness remains one of the central goals of modern ecology. Traditional approaches to exploring these patterns have focused on environmental and ecological correlates of observed species richness. Recently, some have suggested these approaches suffer from the lack of an appropriate null model that accounts for species ranges being constrained to occur within a bounded domain. Proponents of these null geometric constraint models (GCMs), and the mid-domain effect these models produce, argue their utility in identifying meaningful gradients in species richness. This idea has generated substantial debate. Here we discuss what we believe are the three major challenges in the application of GCMs. First, we argue that there are actually two equally valid null models for the random placement of species ranges within a domain, one of which actually predicts a uniform distribution of species richness. Second, we highlight the numerous decisions that must be made to implement a GCM that lead to marked differences in the predictions of the null model. Finally, we discuss challenges in evaluating the importance of GCMs once they have been implemented. |
| |
Keywords: | Debate diversity geometric constraint model mid-domain effect null model species range species richness |
|
|