21155772
not annotated - annotated - LINNAEUS only
The Serengeti food web: empirical quantification and analysis of topological changes under increasing human impact.
1. To address effects of land use and human overexploitation on wildlife populations, it is essential to better understand how human activities have changed species composition, diversity and functioning. Theoretical studies modelled how network properties change under human-induced, non-random species loss. However, we lack data on realistic species-loss sequences in threatened, real-world food webs to parameterize these models. 2. Here, we present a first size-structured topological food web of one of the most pristine terrestrial ecosystems in the world, the Serengeti ecosystem (Tanzania). The food web consists of 95 grouped nodes and includes both invertebrates and vertebrates ranging from body masses between 10(-7) and 10(4) kg. 3. We study the topological changes in this food web that result from the simulated IUCN-based species-loss sequence representing current species vulnerability to human disturbances in and around this savanna ecosystem. We then compare this realistic extinction scenario with other extinction sequences based on body size and connectance and perform an analysis of robustness of this savanna food web. 4. We demonstrate that real-world species loss in this case starts with the biggest (mega) herbivores and top predators, causing higher predator-prey mass ratios. However, unlike theoretically modelled linear species deletion sequences, this causes poor-connected species to be lost first, while more highly connected species become lost as human impact progresses. This food web shows high robustness to decreasing body size and increasing connectance deletion sequences compared with a high sensitivity to the decreasing connectance deletion scenario. 5. Furthermore, based on the current knowledge of the Serengeti ecosystem, we discuss how the focus on food web topology alone, disregarding nontrophic interactions, may lead to an underestimation of human impacts on wildlife communities, with the number of trophic links affected by a factor of two. 6. This study underlines the importance of integrative efforts between the development of food web theory and basic field work approaches in the quantification of the structure of interaction networks to sustain natural ecosystems in a changing world.
Ann file
T1 Species 102 107 human
N1 Reference T1 Taxonomy:9606
T2 Species 156 161 human
N2 Reference T2 Taxonomy:9606
T3 Species 245 250 human
N3 Reference T3 Taxonomy:9606
T4 Species 388 393 human
N4 Reference T4 Taxonomy:9606
T5 Species 1025 1030 human
N5 Reference T5 Taxonomy:9606
T6 Species 1605 1610 human
N6 Reference T6 Taxonomy:9606
T7 Species 2018 2023 human
N7 Reference T7 Taxonomy:9606