Taking fear back into the Marginal Value Theorem: the risk-MVT and optimal boldnessuse asterix (*) to get italics

Vincent Calcagno, Frederic Grognard, Frederic M Hamelin, Ludovic MailleretPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"

2024

<p>Foragers exploiting heterogeneous habitats must make strategic movement decisions in order to maximize fitness. Foraging theory has produced very general formalizations of the optimal patch-leaving decisions rational individuals should make. One is Charnov's Marginal Value Theorem (MVT), which models the sequential visit of habitat patches and their spatial distribution. The MVT has a simple intuitive graphical interpretation in terms of gain functions and travel times. However, it considers only energy gains, and the effect of predation risk on the time allocation strategy is notoriously lacking. An important development that includes predation risk was Brown's economic treatment of optimal patch leaving decisions, the basis of giving-up density (GUD) theory, often cited as an extension of the MVT. However, it is a more abstract result that does not have the specificities or graphical appeal of the MVT. Although both successful, the two theories are cited by distinct communities and are seldom connected in texbooks. Here we formally introduce the risk-MVT (rMVT), a generalization of the MVT that can incorporate most types of predation risks. We show that Brown's GUD-theory is equivalent to a rMVT, but applies for one type of predation risk only. The rMVT retains the structure and graphical simplicity of the MVT, but implies a shift from residence time to expected dose of risk (micromort units, as used in decision analysis) as the domain over which rates of gain are computed and maximized. Applications of the rMVT show that different types of risk can yield opposite responses of optimal strategies to an increase in the risk level, and predict differential responses of behaviours observed in experimental versus natural conditions. The risk-MVT can also be used to predict the optimal level of risk taking, or "optimal boldness", and suggests that individuals should generally be bolder in riskier habitats.</p>

https://doi.org/10.5281/zenodo.10058431You should fill this box only if you chose 'Scripts were used to obtain or analyze the results'. URL must start with http:// or https://

Ecology of fear; Giving-up density; Movement; Optimal foraging theory; Residence time; Risk aversion

NonePlease indicate the methods that may require specialised expertise during the peer review process (use a comma to separate various required expertises).

Adaptation, Behavior & Social Evolution, Evolutionary Ecology, Evolutionary Theory, Life History

Andrew King [a.j.king@swansea.ac.uk] suggested: Damien Farine - Damien.Farine@anu.edu.au, Andrew King [a.j.king@swansea.ac.uk] suggested: Grace Davies - ghdavis@ucdavis.edu, Andrew King [a.j.king@swansea.ac.uk] suggested: Marco Fele - 2252927@swansea.ac.uk No need for them to be recommenders of PCIEvolBiol. Please do not suggest reviewers for whom there might be a conflict of interest. Reviewers are not allowed to review preprints written by close colleagues (with whom they have published in the last four years, with whom they have received joint funding in the last four years, or with whom they are currently writing a manuscript, or submitting a grant proposal), or by family members, friends, or anyone for whom bias might affect the nature of the review - see the code of conduct

2023-11-03 13:25:16

Stephen Proulx