What happens when two or more evolving populations interact? I study such coevolutionary dynamics by using mathematical models spanning multiple biological scales, from the ecology of competition, predation and parasitism to the molecular and genetic details of evolutionary adaptations. A particular focus of my work lies on microbial evolution in an environmental arena where population structure changes in time and space, forming a highly dynamic landscape shaped by ecological interactions and coevolutionary feedbacks.

Holobionts and Symbiosis

It is a striking fact that there are at least as many bacterial cells living within the human body as there are human cells. More generally all animals and plants, from unicellular protists to mighty blue whales, are inhabited by diverse communities of microbial organisms. Those microbial lodgers can be symbiotic, commensal or pathogenic and they often have fundamental roles in host immune function and metabolism. As such they form integral parts of their hosts, to the extent that from an evolutionary perspective, the host and its associated microbial community can be viewed as a single unit of selection - the holobiont. I am particularily interested in the multilayered eco-evolutionary dynamics of microbial communities that happen to reside in organisms which are themselves part of a dynamic host population.

Host-Virus Coevolution

Viruses have major impacts on ecosystems across all scales and besides being responsible for the turnover of vast amounts of biomass globally, they can also help maintain diversity and, due to their nature as mobile genetic elements, facilitate horizontal gene transfer in microbial communities. Due to the tight association of viruses with their hosts and short generation times, host-virus interactions have the potential for rapid coevolution and I study how this shapes microbial populations. I am interested in classical antagonistic coevolution where the virus plays a predator-like role, but also in more subtle and potentially even beneficial effects viruses can have on their host populations.

Eco-Evolutionary Theory

While I usually aim to connect my theoretical work as directly as possible to empirical data, ideally working closely with experimentalists, I also enjoy exploring more abstract and conceptual models in ecology and evolution. This includes studying mathematical models from a dynamical systems point of view using analytical and numerical methods.


I am a scientist at the Department for Evolutionary Theory at the Max Planck Institute for Evolutionary Biology in Plön. Before embarking on the adventure of an academic career I learned the art of coding and software development at Bertelsmann AG and arvato Systems in my hometown Gütersloh. I studied in Osnabrück earning Diploma and PhD degrees in the Theoretical Systems Science group of Horst Malchow. I then left the North German Plain and crossed the Channel to join Ivana Gudelj's group at the University of Exeter. After moving back to Germany I spent two years with the Ecology and Ecosystem Modelling Group of Ursula Gaedke at the University of Potsdam before arriving in Plön.

Besides my research I enjoy riding motorcycles and I believe that this is not only great fun, but in fact a very valuable experience. Or as one of the worlds leading young scientists puts it: Motorcycles are great for their acceleration. Every physicist should learn to ride a motorcycle. It gives one a certain physical intuition. --Sabrina Gonzalez Pasterski


One man's trash is another man's treasure - the effect of bacteria on phytoplankton-zooplankton interactions in chemostat systems

Raatz, M., Schälicke, S., Sieber, M., Wacker, A. and Gaedke, U.
bioRxiv (2018)doi

Temperate phages as self-replicating weapons in bacterial competition

Li, X-Y., Lachnit, T., Fraune, S., Bosch, T. C. G., Traulsen, A. and Sieber, M.
Journal of the Royal Society Interface, 14:20170563 (2017)doi|

Eco-evolutionary dynamics in a coevolving host-virus system

Frickel, J., Sieber, M. and Becks, L.
Ecology Letters, 19:450-459 (2016)doi|

Do-or-die life cycles and diverse post-infection resistance mechanisms limit the evolution of parasite host ranges

Sieber, M. and Gudelj, I.
Ecology Letters, 17:491-498 (2014)doi|

Dispersal network structure and infection mechanism shape diversity in a coevolutionary bacteria-phage system

Sieber, M., Robb, M., Forde, S. E. and Gudelj, I.
The ISME Journal, 8:504-514 (2014)doi|

Disease-induced modification of prey competition in eco-epidemiological models

Sieber, M., Malchow, H. and Hilker, F. M.
Ecological Complexity, 18:74-82 (2014)doi|

The hydra effect in predator-prey models

Sieber, M. and Hilker, F. M.
Journal of Mathematical Biology, 64:341-360 (2012)doi|

Prey, predators, parasites: intraguild predation or simpler community modules in disguise?

Sieber, M. and Hilker, F. M.
Journal of Animal Ecology, 80:414-421 (2011)doi|

Partial differential equations

Sieber, M. and Malchow, H.
In Modelling complex ecological dynamics, Jopp, Reuter and Breckling (Eds.). Springer-Verlag, Berlin, Heidelberg (2011).

Noise can prevent onset of chaos in spatiotemporal population dynamics

Petrovskii, S. V, Morozov, A., Malchow, H. and Sieber, M.
European Physical Journal B, 78:253-264 (2010)doi|

Oscillations vs. chaotic waves: Attractor selection in bistable stochastic reaction-diffusion systems

Sieber, M. and Malchow, H.
European Physical Journal Special Topics, 187:95-99 (2010)doi|

Noise-induced suppression of periodic travelling waves in oscillatory reaction-diffusion systems

Sieber, M., Malchow, H. and Petrovskii, S. V.
Proceedings of the Royal Society A, 466:1903-1917 (2010)doi|

Constructive effects of environmental noise in an excitable prey-predator plankton system with infected prey

Sieber, M., Malchow, H. and Schimansky-Geier, L.
Ecological Complexity, 4:223-233 (2007)doi|