Homepage of Arnulf Koehncke
I am a theoretical evolutionary biologist and ecologist working on a wide variety of topics. Currently, I am in the last year of my PhD under the joint supervision of Peter Hammerstein at Humboldt-University's Institute for Theoretical Biology (ITB) and Olof Leimar at Stockholms Universitet, Sweden.
A main focus of my reserch lies on Darwinian decision making in ovipositing insects---how do insects decide where to lay their eggs, what are optimal optimal decision strategies of host plant choice, and how are these strategies shaped by environmental, developmental, and cognitive factors. This on-going work will form the basis of my PhD-thesis.
My work on optimal insect oviposition can be divided into three projects that use various theoretical approaches from analytic modeling and adaptive dynamics to individual based simulations. The first of these projects examines how strategic approaches to oviposition can help shed light on such puzzling insect behavior as egg-limitation, i.e. the phenomenon that female insects run out of eggs during their lifetime. The second project takes a sceptic look at the idea that spatial heterogeneity can lead to the evolution of generalism. And the third project focuses on how, in the specific case of a polyphagous butterfly, temporal variation in host availability may have lead to the evolution of a wider diet breadth. In all of these projects, I work with Olof Leimar and Peter Hammerstein; some of the projects are more extended collborations with entomogists and botanists from Stockholms University, among others Johan Ehrlén, Karl Gotthard, and Christer Wiklund.
I am also interested in biological invasions, currently one of the biggest threats to biodiversity worldwide. Specifically, I am interested in the role evolution plays in the establishment of invading species and also in the mitigation of biological invasions. Together with Arndt Telschow (Westfalian Wilhelms University Münster, Germany) and Michio Kondoh (Ryokoku University, Japan), I have recently completed a theoretical study that showed how the invasibility of a community to an invading consumer can be an emergent property of the population structure of this community if rapid adaptation of loca natives interfers with invader establishment (Oikos, in press).
The intracellular parasite Wolbachia
On the side, I also do theoretical work on the intracellular bacteria Wolbachia, a reproductive parasite that affects around 40% of all insect species (Zug & Hammerstein 2012). In collaboration with John H. Werren (University of Rochester, USA), Peter Hammerstein (ITB), and Arndt Telschow (Westfalian Wilhelms University Münster, Germany), I have demonstrated theoretically how hosts of Wolbachia are likely to evolve resistance so that, over evolutionary time, Wolbachia disappear from host populations (Link to full text). Together with Roman Zug and Peter Hammerstein (both ITB), we have examined how, even though the evolution of resistance leads to transient infections in individual species, the epidemiology of Wolbachia may permit the parasite to infect a large proportion of the global set of arthropod species (Zug et al., 2012). Additionally, together with Benjamin Bossan and Peter Hammerstein (both ITB), we have proposed a new model for how Wolbachia generate cytoplasmic incompatibility---the phenomenon that infected males often cannot mate successfully with uninfected females ( Link to full text).
Other research interests
I am also interested in many other evolutionary and ecological topics ranging from human decision making and evolutionary game theory to more "classical" behavioral ecology. I have also worked empirically on subspeciation genetics in the willow warbler (Phylloscopus trochilus) with Staffan Bensch in Lund University's Molecular Population Biology Lab. Moreover, I like to explore the interface of biology and philosophy as well as the history of biology and, as a result, have co-founded and co-organise the Journal Club Evolutionary Biology together with Victor Anaya.
Besides theoretical biology, another scientific interest of mine is conservation. Recently, I was lucky to be able to spend six insightful months in Phnom Penh, where I worked as an intern with WWF-Cambodia performing both research- and communication-tasks. Among other things, I conducted a field study on the drying-out dynamics of waterholes in northeastern Cambodia's pristine dry forests (here's a report in German with pictures) as well as restructured WWF-Cambodia's website. My stay in Cambodia was funded by the Carlo-Schmid-Programme, a joint initiative of the German Academic Exchange Service (DAAD) and the German National Academic Foundation (Studienstiftung).
I currently teach seminars and practice sessions in Evolutionary Biology for bachelor- and master-students, all of which are parts of the modules Evolutionary Theory across the Life Sciences I and II. Most recently, the practice session that I tought was voted second best practice session of the winter-term 2011/2012, and the seminar that I co-organised was even voted best seminar of the term (see link in German).
I have co-supervised thesis work by three diploma- and one bachelor-student on Wolbachia- as well as Ageing-related theoretical questions. In the past, I have taught tutorials and practice sessions in Evolution, Theoretical Biology, Evolutionary Game Theory and Evolutionary Genetics, as well as in Programming in C++. In 2011, I completed an eight-month training-course "Online Lehre Lernen" at Berlin's Technical University to learn new skills in online teaching.
In my freetime, I listen to and make music (see here and here), watch birds, take photos, like to travel, and occasionally play team sports, currently mostly basketball with our newly established ITB-team.
Koehncke A, Telschow A, Kondoh M (2013) Invasibility as an emergent property of native metapopulation structure. Oikos 122: 332-340. Editor's choice. doi: 10.1111/j.1600-0706.2012.20677.x Link to article at journal website.
Bossan B, Hammerstein P, Koehncke A (2013) We were all young once - an intragenomic perspective an parent-offspring conflict. Proceedings of the Royal Society B: Biological Sciences 280: 20122637. doi: 10.1098/rspb.2012.2637. Download post-print pdf. Link to article at journal website.
Zug R, Koehncke A, Hammerstein P (2012) Epidemiology in evolutionary time: The case of Wolbachia horizontal transmission between arthropod host species. Journal of Evolutionary Biology 25: 2149–2160. Editor's choice. doi: 10.1111/j.1420-9101.2012.02601.x Download post-print pdf. Link to article at journal website..
Bossan B, Koehncke A, Hammerstein P (2011) A new model and method for understanding Wolbachia-induced cytoplasmic incompatibility. PLoS ONE 6(5): e19757. Download PDF, Link to article at journal website.
Koehncke A, Telschow A, Werren JH, Hammerstein P (2009) Life and Death of an Influential Passenger: Wolbachia and the Evolution of CI-Modifiers by Their Hosts. PLoS ONE 4(2): e4425. Download PDF, Link to article at journal website.
Koehncke A, Leimar O, Hammerstein P (2011) The challenges of optimal oviposition - Ecological and developmental constraints, Poster at the Entomology Congress 2011 of the German Society for General and Applied Entomology (DGaaE) in Berlin. Download PDF.
Koehncke A, Kondoh M, Telschow A (2007) Boom-and-bust patterns in models with spatially explicit structure, Poster at the 2nd International Symposium on Dynamical Systems Theory and Its Applications to Biology and Environmental Sciences in Shizuoka, Japan. Download PDF.