Habitat loss and the disassembly of mutalistic networks


M. A. Fortuna, Integrative Ecology Group Estación Biológica de Doñana, EBD-CSIC, Américo Vespucio s/n, ES-41092 Sevilla, Spain. E-mail: fortuna@ebd.csic.es


Recent studies have described the architecture of plant–animal mutualistic networks, but little is known on how such networks disassemble as a consequence of global change. This is a relevant question because 1) species interactions seem to be very susceptible to habitat loss, and 2) the loss of a critical fraction of interactions can abruptly change the topology of the entire network with potential consequences for its functioning. Here we develop a spatially explicit metacommunity model based on the structure of 30 real mutualistic networks. We find that there is a critical value of habitat destruction beyond which interactions are lost very fast. Second, there is a homogeneous distribution of the number of interactions per patch when the habitat is pristine, while this becomes very skewed at the brink of extinction. This increase in skewness is discussed in the context of potential indicators of network collapse.