This is the joint group meeting of the research groups in Applied Systems Science and Theoretical Systems Science. We discuss new results, bounce off new ideas, practice talks, and do journals clubs - just to mention a few of our activities.
We are always happy to host guests and visitors. If you're interested or would like get involved, please don't hesitate to get in touch!
Summer Semester 2015
|Tue 05.05.2015||10:15||Prof. Dr. Horst MalchowInstitute of Environmental Systems Research, Osnabrück||Ingredients of spatiotemporal pattern formation in population dynamics.||35/E25||USF Research Seminar|
|Wed 06.05.2015||11:00||Prof. Dr. Frank M. HilkerInstitute of Environmental Systems Research, Osnabrück||Introduction to XPPAUT.||66/E16|
|Tue 12.05.2015||10:15||Prof. Dr. Eduardo LizUniversity of Vigo (Spain)||Logistic population models revisited.||35/E25||USF Research Seminar|
|Tue 02.06.2015||10:15||Vanessa SchakauInstitute of Environmental Systems Research, Osnabrück||Infectious diseases in streams and rivers.||35/E25||USF Research Seminar|
|Fri 05.06.2015||11:00||Daniel RitterskampUniversity of Oldenburg||Evolutionary Dynamics in Food Webs: Influence of Interaction Range, Resource Distribution and Space||66/E01|
|Mon 08.06.2015||16:00||Fanny GrollUniversity of Cologne||Chaotic attractor in 2-prey-1-predator-system originates from interplay of limit cycles||66/E01|
|Tue 09.06.2015||10:15||Virgile BaudrotUniversité de Franche-Comté, Besançon (FRA)||The foraging behavior on trophically transmitted parasites.||35/E25|
|Tue 16.06.2015||10:15||Federico RoccatiUniversity of Torino (ITA)||Packs of predators vs. groups of prey||35/E25|
|Marta PaliagaUniversity of Torino (ITA)||Disease infection undermining predator cooperation||35/E25|
|Thu 18.06.2015||11:30||Zepeng Sun University of Amsterdam (The Netherlands)||What can we learn from seasonal reproduction?||93/E15|
|Fri 19.06.2015||11:30||Gunnar Petter University of Göttingen||Simulating the long-term dynamics of tropical forests using functional-structural tree models||35/E23-E24|
|Mon 22.06.2015||11:30||Veronika BernhauerovaMasaryk University, Brno (Czech Republic)||Evolution of male-killing in horizontally transmitted parasites||66/101|
|Tue 23.06.2015||10:15||Philipp GorrisInstitute of Environmental Systems Research, Osnabrück||Developing a Graduate School at the IUSF - Introduction and Discussion||35/E25||USF Research Seminar|
|Thu 25.06.2015||11:30||Matthew W. AdamsonUniversity of Leicester (UK)||Cyclic competition, virus evolution and structural sensitivity||35/E21|
|Fri 26.06.2015||11:00||Michael BengfortInstitute of Environmental Systems Research, Osnabrück||Some ideas of the Dynatrait project and possible contributions.||66/E01|
|Tue 14.07.2015||11:15||Alexander AhringInstitute of Environmental Systems Research, Osnabrück||Modellansatz zur Berücksichtigung diffuser Substanzeinträge in Fließgewässer für das georeferenzierte Expositionsmodell GREAT-ER. (Master Thesis)||35/E25|
|Thu 30.07.2015||15:00||Eric SieroLeiden University (NL)||Resilience of banded vegetation on slopes.||66/E01|
|Tue 11.08.2015||14:00||Jane NdunguUniversity of Twente (NL)||Synergy in system modeling, field measurements, and remote sensing||93/E01|
|Thu 20.08.2015||13:30||Practice talks MPDE-15||t.b.a.|
Abstracts of selected talks
Eduardo Liz, Departamento de Matemática Aplicada II, Universidad de Vigo (España)
Logistic population models revisited
The logistic equation is one of the best known models of population growth. The original ODE proposed by Verhulst inspired other related models which exhibit rich dynamics; for example, the discrete logistic equation (quadratic map) became a paradigm of chaos after the seminal papers of May.
In this talk, we consider logistic models of exploited populations, focusing on the changes in the dynamics as the harvesting effort is increased. In this way, we discuss the global dynamics and highlight the link among different logistic equations usually employed in population models.
Daniel Ritterskamp and Bernd Blasius (ICBM, University of Oldenburg)
Evolutionary Dynamics in Food Webs: Influence of Interaction Range, Resource Distribution and Space
Food webs encode feeding interactions in ecological communities, originating from an interplay of evolutionary and ecological processes. Here we develop an evolutionary food web model in which feeding interactions between species are related to the relative distance of their adaptive traits in niche space. We present three model variants, which are analyzed using numerical simulations in combination with adaptive theory.
First, considering a single trait (bodysize), we uncover novel evolutionary dynamics, characterized by oscillations of bodysize within whole trophic guilds. Next, we study a system driven by two basal resources at different niche positions. For certain resource configurations this can lead to a dynamic instability of the food web, because the predators can not optimize their trait position towards both resources. This results into tight coupling of ecological and evolutionary dynamics, giving rise to biomass oscillations and intermittence in the population dynamic. Finally, we embed the model into a two dimensional niche space, where the additional niche axis might describe a spatial coordinate. The model is able to produce a wide range of static and dynamic food webs, depending on the width of the interaction kernel.
The structure of these food webs has common features with empirical data (e.g. intervality) that other models lack to describe. We conclude that the interaction of ecological and evolutionary dynamics can give rise to complex behaviour, such as sustained oscillations, intermittency, and ongoing evolution. Combined with spatial considerations, our studies have the potential to predict evolutionary behaviour in real food webs.
University of Cologne
Chaotic attractor in 2-prey-1-predator-system originates from interplay of limit cycles
We investigate the appearance of chaos in communities promoting coexistence. Our paradigm is an aquatic microbial food web comprising two prey and a predator species. We show that even in this small system a regime of chaotic population dynamics is formed over a wide range of intermediate dilution strengths. Specifically, the numerical simulation of the system reveals the presence of a chaotic attractor in the intermediate parameter window between two regimes of periodic coexistence (stable limit cycles). The intermediate structure provides the basis for the stable coexistence of all three species: environmental perturbations may result in huge fluctuations in species abundances, however, the system at large tolerates those perturbations in the sense that the population abundances quickly fall back onto the chaotic attractor manifold and the system remains. This mechanism explains how chaos helps the system to persist and stabilize against migration. The model is in agreement with laboratory studies.
Virgile Baudrot, Antoine Perasso, Clémentine Fritsch and Francis Raoul
Laboratoire Chrono-environnement – UMR 6249, Université de Franche-Comté / CNRS, 16 route de Gray, 25000 Besançon (France)
The foraging behavior on trophically transmitted parasites
Small mammal populations display fluctuating patterns of densities in many ecosystems worldwide, leading their predators to adapt their foraging strategy (the multi-species functional response, MSFR). The predator-preys relationship is the route of transmission of a large number of zoonotic parasites with a complex life cycle (infecting different hosts during their life), like the cestode Echinococcus multilocularis (Em). This parasite is widely distributed in the Northern Hemisphere and is the causative agent of the emerging zoonosis alveolar echinococcosis in humans. The red fox Vulpes vulpes is a typical definitive host (DH) of Em, with, in eastern France, the rodents Microtus arvalis and Arvicola scherman as intermediate hosts.
We described this eco-epidemiological system with ODEs and we computed the basic reproductive number R0, i.e., the number of secondary infections caused by a single primary infection into an otherwise susceptible population. We developed a general approach to model MSFR including accessibility to resources and switching of prey preference by predator. In this framework, we investigated the importance of MSFR and intermediate host diversity on the transmission patterns of Em. Few works have coupled adaptive predator-prey interactions with parasite transmissions, and the inclusion of switching behavior is a first attempt to feed hot topics linking adaptive foraging behavior and IHs diversity. We showed that switching of prey preference may have a dilution or amplification effect, that is a decrease, resp. increase, of the disease risk with an increase of IHs diversity.