Individual-based models

Individual Based Model (IBM) in ecology describes population dynamics by modelling the processes of each individual of this population. The individuals (or agents) can interact with the other agents and their environment and each individual could be unique and autonomous. Moreover, an IBM model can be coupled to a DEB model which describes the physiological processes of each individual (maintenance, growth, reproduction).

IBM models are useful to understand the resulting population-level properties such as persistence, resilience or regulation from all the interactions between the individuals and their environment. They can for example be used to answer scientific questions and help decision making and management. Moreover, such models are gaining increasing interest in ecotoxicology because they incorporate available mechanistic knowledge on the links between responses at the individual level and responses at the population level. Hence, they can predict the effects of a chemical on a population from the effects observed on organisms in laboratory experiments. To this goal, IBM models have first to be able to describe accurately the population dynamics within different ecological conditions in order to be use in ecotoxicology to detect the direct and indirect effects of a chemical on this population.

The consequence of the high level of complexity and precision of IBMs is that these models need a large amount of data on the physiological processes involved at the organism-level. Then, nesting a DEB model within a population dynamics IBM can be useful when existing models and/or data on organism level physiology are available.

DEB-IBM models have already been developed in the METO team for chironomus (Beaudouin et al, 2012), the zebrafish (Beaudouin et al, 2015) and for the threespined stickleback (David et al, 2019a et b).

Key publications

• • Beaudouin R, Dias V, Bonzom JM, Péry A. Individual-based model of Chironomus riparius population dynamics over several generations to explore adaptation following exposure to uranium-spiked sediments. Ecotoxicology 21, 1225-1239.

  • Beaudouin, R; Goussen, B; Piccini, B; Augustine, S; Devillers, J; Brion, F; Pery, ARR. An Individual-Based Model of Zebrafish Population Dynamics Accounting for Energy Dynamics. 2015. PLOS ONE, 10 (5):10.1371/journal.pone.0125841

• David, V., Joachim, S., Porcher, J.M., Beaudouin, R., 2019. Modelling BPA effects on three-spined stickleback population dynamics in mesocosms to improve the understanding of population effects. Science of the Total Environment 692, 854-867.

• David, V., Joachim, S., Tebby, C., Porcher, J.M., Beaudouin, R., 2019. Modelling population dynamics in mesocosms using an individual-based model coupled to a bioenergetics model. Ecological Modelling 398, 55-66.