@article{RyserHaeusslerStarketal.2019, author = {Ryser, Remo and H{\"a}ussler, Johanna and Stark, Markus and Brose, Ulrich and Rall, Bj{\"o}rn C. and Guill, Christian}, title = {The biggest losers: habitat isolation deconsructs complex food webs from top to bottom}, series = {Proceedings of the Royal Society of London : B, Biological sciences}, volume = {286}, journal = {Proceedings of the Royal Society of London : B, Biological sciences}, number = {1908}, publisher = {Royal Society}, address = {London}, issn = {0962-8452}, doi = {10.1098/rspb.2019.1177}, pages = {8}, year = {2019}, abstract = {Habitat fragmentation threatens global biodiversity. To date, there is only limited understanding of how the different aspects of habitat fragmentation (habitat loss, number of fragments and isolation) affect species diversity within complex ecological networks such as food webs. Here, we present a dynamic and spatially explicit food web model which integrates complex food web dynamics at the local scale and species-specific dispersal dynamics at the landscape scale, allowing us to study the interplay of local and spatial processes in metacommunities. We here explore how the number of habitat patches, i.e. the number of fragments, and an increase of habitat isolation affect the species diversity patterns of complex food webs (alpha-,beta-,gamma-, diversities). We specifically test whether there is a trophic dependency in the effect of these two factors on species diversity. In our model, habitat isolation is the main driver causing species loss and diversity decline. Our results emphasize that large-bodied consumer species at high trophic positions go extinct faster than smaller species at lower trophic levels, despite being superior dispersers that connect fragmented landscapes better. We attribute the loss of top species to a combined effect of higher biomass loss during dispersal with increasing habitat isolation in general, and the associated energy limitation in highly fragmented landscapes, preventing higher trophic levels to persist. To maintain trophic-complex and species-rich communities calls for effective conservation planning which considers the interdependence of trophic and spatial dynamics as well as the spatial context of a landscape and its energy availability.}, language = {en} } @article{SchneiderBroseRalletal.2016, author = {Schneider, Florian D. and Brose, Ulrich and Rall, Bj{\"o}rn C. and Guill, Christian}, title = {Animal diversity and ecosystem functioning in dynamic food webs}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/ncomms12718}, pages = {3129 -- 3138}, year = {2016}, abstract = {Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. High animal diversity increases complementarity of herbivores but also increases feeding rates within the consumer guild. Depending on the balance of these counteracting mechanisms, species-rich animal communities may put plants under top-down control or may release them from grazing pressure. Using a dynamic food-web model with body-mass constraints, we simulate ecosystem functions of 20,000 communities of varying animal diversity. We show that diverse animal communities accumulate more biomass and are more exploitative on plants, despite their higher rates of intra-guild predation. However, they do not reduce plant biomass because the communities are composed of larger, and thus energetically more efficient, plant and animal species. This plasticity of community body-size structure reconciles the debate on the consequences of animal species loss for primary productivity.}, language = {en} } @article{BinzerGuillRalletal.2016, author = {Binzer, Amrei and Guill, Christian and Rall, Bj{\"o}rn C. and Brose, Ulrich}, title = {Interactive effects of warming, eutrophication and size structure: impacts on biodiversity and food-web structure}, series = {Global change biology}, volume = {22}, journal = {Global change biology}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/gcb.13086}, pages = {220 -- 227}, year = {2016}, abstract = {Warming and eutrophication are two of the most important global change stressors for natural ecosystems, but their interaction is poorly understood. We used a dynamic model of complex, size-structured food webs to assess interactive effects on diversity and network structure. We found antagonistic impacts: Warming increases diversity in eutrophic systems and decreases it in oligotrophic systems. These effects interact with the community size structure: Communities of similarly sized species such as parasitoid-host systems are stabilized by warming and destabilized by eutrophication, whereas the diversity of size-structured predator-prey networks decreases strongly with warming, but decreases only weakly with eutrophication. Nonrandom extinction risks for generalists and specialists lead to higher connectance in networks without size structure and lower connectance in size-structured communities. Overall, our results unravel interactive impacts of warming and eutrophication and suggest that size structure may serve as an important proxy for predicting the community sensitivity to these global change stressors.}, language = {en} } @article{GrossAllhoffBlasiusetal.2020, author = {Gross, Thilo and Allhoff, Korinna Theresa and Blasius, Bernd and Brose, Ulrich and Drossel, Barbara and Fahimipour, Ashkaan K. and Guill, Christian and Yeakel, Justin D. and Zeng, Fanqi}, title = {Modern models of trophic meta-communities}, series = {Philosophical transactions of the Royal Society of London : B, Biological sciences}, volume = {375}, journal = {Philosophical transactions of the Royal Society of London : B, Biological sciences}, number = {1814}, publisher = {Royal Society}, address = {London}, issn = {0962-8436}, doi = {10.1098/rstb.2019.0455}, pages = {12}, year = {2020}, abstract = {Dispersal and foodweb dynamics have long been studied in separate models. However, over the past decades, it has become abundantly clear that there are intricate interactions between local dynamics and spatial patterns. Trophic meta-communities, i.e. meta-foodwebs, are very complex systems that exhibit complex and often counterintuitive dynamics. Over the past decade, a broad range of modelling approaches have been used to study these systems. In this paper, we review these approaches and the insights that they have revealed. We focus particularly on recent papers that study trophic interactions in spatially extensive settings and highlight the common themes that emerged in different models. There is overwhelming evidence that dispersal (and particularly intermediate levels of dispersal) benefits the maintenance of biodiversity in several different ways. Moreover, some insights have been gained into the effect of different habitat topologies, but these results also show that the exact relationships are much more complex than previously thought, highlighting the need for further research in this area. This article is part of the theme issue 'Integrative research perspectives on marine conservation'.}, language = {en} }