Climate change impacts on body size and food web structure on mountain ecosystems

9 pages, 3 figures, 3 tables

The current distribution of climatic conditions will be rearranged on the globe. To survive, species will have to keep pace with climates as they move. Mountains are among the most affected regions owing to both climate and land-use change. Here, we explore the effects of climate change in the vertebrate food web of the Pyrenees. We investigate elevation range expansions between two time-periods illustrative of warming conditions, to assess: (i) the taxonomic composition of range expanders; (ii) changes in food web properties such as the distribution of links per species and community size-structure; and (iii) what are the specific traits of range expanders that set them apart from the other species in the community—in particular, body mass, diet generalism, vulnerability and trophic position within the food web. We found an upward expansion of species at all elevations, which was not even for all taxonomic groups and trophic positions. At low and intermediate elevations, predator : prey mass ratios were significantly reduced. Expanders were larger, had fewer predators and were, in general, more specialists. Our study shows that elevation range expansions as climate warms have important and predictable impacts on the structure and size distribution of food webs across space

M.L. was contracted in the project Consolider-Ingenio Montes (CSD2008-00040) to construct and analyse the networks, and he is currently supported by Microsoft Research. J.M.M. is supported by a Ramon y Cajal Fellowship (RYC-892 2008-03664, Ministry of Economy CGL2010-20091 and Generalitat de Catalunya 2009SGR142). The participation of J.M.M. at the SIZEMIC Workshop (Hamburg) was supported by the German Research Foundation (JA 1726/3-1) and by the Cluster of Excellence CliSAP (EXC177) (Univ. Hamburg), funded through the DFG. The authors thank all the students, but specially Irene Figueroa and Núria Galiana, who helped in the construction of the database

Peer reviewed