Understanding how similar competing species can coexist is one of the major puzzles of ecology. Field evidence accumulates to show that in many communities, intra-specific competition can be much stronger than inter-specific competition [2], in accordance to the predictions of niche theory. However, much of that evidence comes from unstructured community-level models (Lotka-Volterra and cousins). Many populations do exhibit in contrast stage structure with very different juveniles and adults (e.g., trees, fishes). With stage structure, stronger intraspecific competition could occur at one life-stage (e.g., throughout recruitment [5]), and equal intra- and inter-specific competition at other stages. If so, stage-structured theory could clarify debates on niche (competition intrasp. » intersp.) vs. neutral (intrasp. = intersp.) theories of biodiversity.

In this context, structured models for interacting populations are paramount to understand coexistence. Our ability to connect these structured models to data has recently increased greatly with the advent of Integrated Population Models [4, 1, 9] that combine counts, capture-recapture and reproduction data. They use as a backbone nonlinear matrix models [8], but these remain little explored in a multispecies context. The proposed internship will therefore explore factors that promote coexistence in multispecies nonlinear matrix models (following Moll & Brown [7], Fujiwara et al. [6]), building on recent techniques for sensitivity analysis [3].

Possible questions include:
– How easily can biodiversity maintain through strong intraspecific competition at some stages and neutral competition at other stages?
– Real communities show mixture of positive and negative interactions at different stages [9]. Can this blend of interactions explain diversity maintenance?
– To what model parameters is the community most sensitive to? I.e., what are the parameters that should be estimated with the highest precision?

Depending on the interests of the candidate, models can be tuned to represent different empirical systems. The internship is connected to ANR Democom where we fit multispecies models to data to improve our understanding of community dynamics.

Profile and skills: Master program in quantitative ecology or applied mathematics / Code in R, Matlab or similar / a taste for theory. Writing in French is completely fine, but some proficiency in English will be essential to grasp the theoretical literature.

Supervision: Frédéric Barraquand (Institute of Mathematics of Bordeaux, CNRS & ETI Group, U Bordeaux) and Olivier Gimenez (CEFE Montpellier, CNRS).

Practical information: The internship is currently planned for January to June 2019, but the dates can be adjusted. The internship will take place at the University of Bordeaux and will be compensated  ~ 560 euros per month.

Contact: [email protected]

References

[1] Fitsum Abadi, Olivier Gimenez, Hans Jakober, Wolfgang Stauber, Raphaël Arlettaz, Michael Schaub: “Estimating the strength of density dependence in the presence of observation errors using integrated population models”, Ecological Modelling, pp. 1—9, 2012.

[2] Peter B Adler, Danielle Smull, Karen H Beard, Ryan T Choi, Tucker Furniss, Andrew Kulmatiski, Joan M Meiners, Andrew T Tredennick, Kari E Veblen: “Competition and coexistence in plant communities: intraspecific competition is stronger than interspecific competition”, Ecology letters, pp. 1319—1329, 2018.

[3] György Barabás, Géza Meszéna, Annette Ostling: “Fixed point sensitivity analysis of interacting structured populations”, Theoretical population biology, pp. 97—106, 2014.

[4] Panagiotis Besbeas, Stephen N Freeman, Byron JT Morgan, Edward A Catchpole: “Integrating mark—recapture—recovery and census data to estimate animal abundance and demographic parameters”, Biometrics, pp. 540—547, 2002.

[5] Chengjin Chu, Peter B Adler: “Large niche differences emerge at the recruitment stage to stabilize grassland coexistence”, Ecological Monographs, pp. 373—392, 2015.

[6] Masami Fujiwara, Georgia Pfeiffer, May Boggess, Sarah Day, Jay Walton: “Coexistence of competing stage-structured populations”, Scientific Reports, pp. 107, 2011.

[7] Jason D Moll, Joel S Brown: “Competition and coexistence with multiple life-history stages”, The American Naturalist, pp. 839—843, 2008.

[8] Michael G Neubert, Hal Caswell: “Density-dependent vital rates and their population dynamic consequences”, Journal of Mathematical Biology, pp. 103—121, 2000.

[9] Guillaume Péron, David N Koons: “Integrated modeling of communities: parasitism, competition, and demographic synchrony in sympatric ducks”, Ecology, pp. 2456—2464, 2012.

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Pout toute autre question, vous pouvez contacter [email protected].