PT  - JOURNAL ARTICLE
AU  - AK Fahimipour
AU  - KE Anderson
AU  - RJ Williams
TI  - Compensation masks trophic cascades in complex food webs
AID  - 10.1101/068569
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 068569
4099  - http://biorxiv.org/content/early/2016/08/09/068569.short
4100  - http://biorxiv.org/content/early/2016/08/09/068569.full
AB  - Ecological networks, or food webs, describe the feeding relationships between interacting species within an ecosystem. Understanding how the complexity of these networks influences their response to changing top-down control is a central challenge in ecology. Here, we provide a model-based investigation of trophic cascades — an oft-studied ecological phenomenon that occurs when changes in the biomass of top predators indirectly effect changes in the biomass of primary producers — in complex food webs that are representative of the structure of real ecosystems. Our results reveal that strong cascades occur primarily in small and weakly connected food webs, a result very much in agreement with empirical studies. The primary mechanism underlying weak or absent cascades was a strong compensatory response; in most webs predators induced large population level cascades that were masked by changes in the opposite direction by other species in the same trophic guild. Thus, the search for a general theory of trophic cascades in food webs should focus on uncovering the features of real ecosystems that promote or preclude compensation within functional guilds.