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Christian Jost Assistant Professor email: jost<at>cict.fr tél : 05 61 55 64 37, fax : 05 61 55 61 54   Research Teaching Publications Amorphophallus konjac

Research

I am interested in the modelling of biological phenomena and in the identification of the mechanisms behind a globally observed pattern. During my PhD the patterns were predator-prey dynamics and I was trying to identify the underlying functional response (predator consumption). Since my arrival at the CRCA (Dynactom research group) my interests have shifted to the self-oganized phenomena that can be found in social insects. Direct animal observation permits to quantify and model their individual behaviour, which in turn allows to predict (and validate) what should be observed on the collective level. This approach requires to combine tools from statistics and dynamical systems. The current surge in Systems Biology relies exactly on this combination of biological experiment, statistical analysis and dynamic modelling. The self-organized processes in social insects are a compelling biological system where one can control and validate all the steps.

I am particuarly involved in two projects of my research group Dynactom:

• Construction phenomena in social insects such as ants or termites: experimental study, characterisation of the individual behaviours and modelling in order to link to the resulting collective behaviours
• Corpse clustering in ants: the clustering of objects is a precursor to construction but simpler in its experimental study - we therefore use it to study how this self-organized process is coupled with environmental templates such as air-currents or temperature.

Teaching

See my french page.

Publications

In Animal behaviour (current research)

• Jost C, Haifig I, Camargo-Dietrich CRR, Costa-Leonardo AM. A comparative tunnelling network approach to assess interspecific competition effects in termites. Insectes Sociaux (in press, doi: 10.1007/s00040-012-0229-7 and see here for additional photos/movies).
• Haifig I, Jost C, Janei V, Costa-Leonardo AM. The size of excavators within a polymorphic termite species governs tunnel topology. Animal Behaviour 2011, 82 1409-1414 (doi: 10.1016/j.anbehav.2011.09.025)
• Perna A, Kuntz P, Theraulaz G, Jost C. From local growth to global optimization in insect built networks. In Biologically inspired networking and sensing: algorithms and architectures, Lio P and Verma D (eds), IGI Global 2011 (doi : 10.4018/978-1-61350-092-7)
• Gautrais J, Jost C, Soria M, Campo A, Motsch S, Fournier R, Blanco S, Theraulaz G. Analysing fish movement as a persistent turning walker. J Math Biol 58, 429-445, 2009 (doi: 10.1007/s00285-008-0198-7, ).
• Garnier S, Gautrais J, Asadpour M, Jost C, Theraulaz G. Self-organized aggregation triggers collective decision making in a group of cockroach-like robots. Adaptive Behaviour 2009, 17, 109-133 (doi: 10.1177/1059712309103430, ).
• Perna A, Valverde S, Gautrais J, Jost C, Solé R, Kuntz P, Theraulaz G. Topological efficiency in three-dimensional gallery networks of termite nests. Physica A 387, 6235-6244, 2008 (doi:10.1016/j.physa.2008.07.019, )
• Perna A, Jost C, Valverde S, Gautrais J, Theraulaz G, Kuntz P. The topological fortress of termites. BIOWIRE Lecture Notes in Computer Science (Springer) 5151, 165-173, 2008 (eds Liò, Crowcroft, Verma, ).
• Perna E, Jost C, Couturier E, Valverde S, Douady S, Theraulaz G. The structure of gallery networks in the nests of termite Cubitermes spp. revealed by X-ray tomography. Naturwissenschaften 95, 877-884, 2008 (doi:10.1007/s00114-008-0388-6, )
• Casellas E, Gautrais J, Fournier R, Blanco S, Combe M, Fourcassié F, Theraulaz G, Jost C. From individual to collective displacements in heterogenous environments, Journal of theoretical Biology, 250, 424-434, 2007. (doi:10.1016/j.jtbi.2007.10.011, )
• Garnier S, Jost C, Gautrais J, Asadpour M, Caprari G, Jeanson R., Grimal A, Theraulaz G. The Embodiment of Cockroach Aggregation Behavior in a Group of Micro-Robots. Artificial Life, 14, 387-408, 2008. (doi: 10.1162/artl.2008.14.4.14400, ).
• Gautrais J., Jost C., Theraulaz G. Key behavioural factors in a self-organised fish school model. Annales zoologici Fennici, online available.

• Jost C., Verret J., Casellas E., Gautrais J., Challet M., Lluc J., Blanco S., Clifton MJ., Theraulaz G. The interplay between a self-organized process and an environmental template: corpse clustering under the influence of air currents in ants. Journal of the Royal Society Interface, 4, 107-116, 2007, .

• Challet M., Fourcassié V., Blanco S., Fournier R., Theraulaz G., Jost C. A new test of random walks in heterogeneous environments. Naturwissenschaften 92: 367-370 (2005). (, download Erratum Fig 1)
  Code to simulate Random walks and to illustrate the property used in this paper (use R to run the simulations)
• Challet, M., Jost C., Grimal A., Lluc J., Theraulaz G. How temperature influences displacemnts and corpse aggregation behaviors in the ant Messor sancta. Insectes sociaux, 52, 305-315, 2005 ,
• Garnier S, Jost C, Jeanson R, Gautrais J, Asadpour M, Caprari G, Theraulaz G. Aggregation Behaviour as a Source of Collective Decision in a Group of Cockroach-Like-Robots. Lecture Notes in Computer Science, 3630, 196-178, 2005, .
• Jeanson, R. , Rivault, C., Deneubourg, J.L., Blanco, S., Fournier, R., Jost, C. & Theraulaz, G. Self-organised aggregation in cockroaches, Animal Behaviour 69, 169-180, 2005 (doi: 10.1016/j.anbehav.2004.02.009, )
• Gautrais, J., Jost, C., Jeanson, R., Theraulaz, G. How individual interactions control aggregation patterns in gregarious arthropods. Interaction Studies 5, 245-269, 2004. (doi: 10.1007/s00285-008-0198-7, )

In ecology (PhD and Post-doc)

• Jost, C., Devulder, G., Vucetich, J.A., Peterson, R.O., Arditi, R. The wolves of Isle Royale display scale-invariant satiation and ratio-dependent predation on moose. Journal of Animal Ecology 74, 809-816, 2005. (paper, , copyright notice)
• Arditi R, Callois J-M, Tyutyunov Y, Jost C. Does mutual interference always stabilize predator–prey
  dynamics? A comparison of models. C. R. Biologies 327: 1037–1057, 2004,
  
• Jost, C., Lawrence, C., Campolongo, F., van de Bund, W., Hill, S., DeAngelis, D. L. The effects of mixotrophy on the stability and dynamics of a simple planktonic food web model. Theoretical Population Biology 66, 37-51, 2004, .
• Y. Tyutyunov, I. Senina, R. Arditi & C. Jost. 2002. Extinction risk assessment of harvested pike-perch population in the Azov Sea. Ecological Modelling 149: 297-311, .
• C. Jost & R. Arditi. 2001. From pattern to process: identifying predator-prey interactions. Population Ecology 43: 229-243, .
• C. Jost & S. Ellner. 2000. Testing for predator dependence in predator-prey dynamics: a nonparametric approach. Proc. Roy. Soc. Lond. B 267: 1611-1620. (, get the dataset, get the Electronic Appendix)
• C. Jost & R. Arditi. 2000. Identifying predator-prey processes from time series data. Theoretical Population Biology 57: 325-337, .
• C. Jost. 2000. Predator-prey theory: hidden twins in ecology and microbiology. Oikos 90: 202-208, .
• S. Ponsard, R. Arditi, C. Jost. 2000. Assessing top-down and bottom-up control in a litter-based soil macroinvertebrate food chain. Oikos 89: 524-540, .
• C. Jost, O. Arino & R. Arditi. 1999. Behavior of the (0,0) equilibrium in a ratio-dependent predator-prey model. Bulletin of Mathematical Biology 61: 19-32. (, download Erratum)
• M. M. Dacorogna, U. A. Müller, C. Jost, O. V. Pictet, R. B. Olsen & J. R. Ward. 1995. Heterogeneous real-time trading strategies in the foreign exchange market. The European Journal of Finance 1: 383-403.

My PhD thesis (in case you want to download it)

• C. Jost.1998. Comparing predator-prey models qualitatively and quantitatively with ecological time-series data. PhD-Thesis, Institut national agronomique Paris-Grignon.(Pdf-Version )

And, last not least, my Amorphophallus konjac continues to enthrall my collegues

Flower of 2002: it is untypical in that the flower grew in autumn while the leaf was still activ.		The flower of 2004 grew as expected in the spring.	The flower of 2005 : nicer than ever, with its characteristic perfume.		And since that year it attracts regularly my collegues (Julie Carcaud)	In 2012 I didn't dare bring it to the lab, but it was as beautiful as ever.