TY - JOUR A1 - Curtsdotter, Alva A1 - Binzer, Amrei A1 - Brose, Ulrich A1 - de Castro, Francisco A1 - Ebenman, Bo A1 - Ekloef, Anna A1 - Riede, Jens O. A1 - Thierry, Aaron A1 - Rall, Bjoern C. T1 - Robustness to secondary extinctions comparing trait-based sequential deletions in static and dynamic food webs JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - The loss of species from ecological communities can unleash a cascade of secondary extinctions, the risk and extent of which are likely to depend on the traits of the species that are lost from the community. To identify species traits that have the greatest impact on food web robustness to species loss we here subject allometrically scaled, dynamical food web models to several deletion sequences based on species' connectivity, generality, vulnerability or body mass. Further, to evaluate the relative importance of dynamical to topological effects we compare robustness between dynamical and purely topological models. This comparison reveals that the topological approach overestimates robustness in general and for certain sequences in particular. Top-down directed sequences have no or very low impact on robustness in topological analyses, while the dynamical analysis reveals that they may be as important as high-impact bottom-up directed sequences. Moreover, there are no deletion sequences that result, on average, in no or very few secondary extinctions in the dynamical approach. Instead, the least detrimental sequence in the dynamical approach yields an average robustness similar to the most detrimental (non-basal) deletion sequence in the topological approach. Hence, a topological analysis may lead to erroneous conclusions concerning both the relative and the absolute importance of different species traits for robustness. The dynamical sequential deletion analysis shows that food webs are least robust to the loss of species that have many trophic links or that occupy low trophic levels. In contrast to previous studies we can infer, albeit indirectly, that secondary extinctions were triggered by both bottom-up and top-down cascades. KW - Species loss KW - Extinction cascades KW - Top-down effect KW - Bottom-up effect KW - Stability KW - Body size KW - Trophic interactions KW - Vulnerability KW - Generality KW - Keystone species Y1 - 2011 U6 - https://doi.org/10.1016/j.baae.2011.09.008 SN - 1439-1791 VL - 12 IS - 7 SP - 571 EP - 580 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Riede, Jens O. A1 - Binzer, Amrei A1 - Brose, Ulrich A1 - de Castro, Francisco A1 - Curtsdotter, Alva A1 - Rall, Bjoern C. A1 - Ekloef, Anna T1 - Size-based food web characteristics govern the response to species extinctions JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - How ecological communities react to species extinctions is a long-standing yet current question in ecology. The species constituting the basic units of ecosystems interact with each other forming complex networks of trophic relationships and the characteristics of these networks are highly important for the consequences of species extinction. Here we take a more general approach and analyze a broad range of network characteristics and their role in determining food web susceptibility to secondary extinctions. We extend previous studies, that have focused on the consequences of topological and dynamical food web parameters for food web robustness, by also defining network-wide characteristics depending on the relationships between the distribution of species body masses and other species characteristics. We use a bioenergetic dynamical model to simulate realistically structured model food webs that differ in their structural and dynamical properties as well as their size structure. In order to measure food web robustness we calculated the proportion of species going secondarily extinct. A multiple regression analysis was then used to fit a general model relating the proportion of species going secondarily extinct to the measured food web properties. Our results show that there are multiple factors from all three groups of food web characteristics that affect food web robustness. However, we find the most striking effect was related to the body mass abundance relationship which points to the importance of body mass relationships for food web stability. KW - Body mass-abundance KW - Connectance KW - Food web robustness KW - Hill exponent KW - Size structure KW - Secondary extinctions Y1 - 2011 U6 - https://doi.org/10.1016/j.baae.2011.09.006 SN - 1439-1791 VL - 12 IS - 7 SP - 581 EP - 589 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Binzer, Amrei A1 - Brose, Ulrich A1 - Curtsdotter, Alva A1 - Ekloef, Anna A1 - Rall, Bjoern C. A1 - Riede, Jens O. A1 - de Castro, Francisco T1 - The susceptibility of species to extinctions in model communities JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - Despite the fact that the loss of a species from a community has the potential to cause a dramatic decline in biodiversity, for example through cascades of secondary extinctions, little is known about the factors contributing to the extinction risk of any particular species. Here we expand earlier modeling approaches using a dynamic food-web model that accounts for bottom-up as well as top-down effects. We investigate what factors influence a species' extinction risk and time to extinction of the non-persistent species. We identified three basic properties that affect a species' risk of extinction. The highest extinction risk is born by species with (1) low energy input (e.g. high trophic level), (2) susceptibility to the loss of energy pathways (e.g. specialists with few prey species) and (3) dynamic instability (e.g. low Hill exponent and reliance on homogeneous energy channels when feeding on similarly sized prey). Interestingly, and different from field studies, we found that the trophic level and not the body mass of a species influences its extinction risk. On the other hand, body mass is the single most important factor determining the time to extinction of a species, resulting in small species dying first. This suggests that in the field the trophic level might have more influence on the extinction risk than presently recognized. KW - Extinction risk KW - Allometry KW - Dynamic modeling Y1 - 2011 U6 - https://doi.org/10.1016/j.baae.2011.09.002 SN - 1439-1791 VL - 12 IS - 7 SP - 590 EP - 599 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Binzer, Amrei A1 - Guill, Christian A1 - Rall, Björn C. A1 - Brose, Ulrich T1 - Interactive effects of warming, eutrophication and size structure: impacts on biodiversity and food-web structure JF - Global change biology N2 - 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. KW - complex food webs KW - extinctions KW - generalists KW - global change KW - size structure KW - specialists Y1 - 2016 U6 - https://doi.org/10.1111/gcb.13086 SN - 1354-1013 SN - 1365-2486 VL - 22 SP - 220 EP - 227 PB - Wiley-Blackwell CY - Hoboken ER -