How optimal foragers should respond to habitat changes: on the consequences of habitat conversion
- 8 Downloads
The marginal value theorem (MVT) provides a framework to predict how habitat modifications related to the distribution of resourcesover patches should impact the realized fitness of individuals and their optimal rate of movement (or patch residence times) across the habitat. The MVT theory has focused on the consequences of changing the shape of the gain functions in some patches, describing for instance, patch enrichment. However, an alternative form of habitat modification is habitat conversion, whereby patches are converted from one existing type to another (e.g., closed habitat to open habitat). In such a case, the set of gain functions existing in the habitat does not change, only their relative frequencies does. This case however has received comparatively little attention. Here we analyze mathematically the consequences of habitat conversion under the MVT. We study how realized fitness and the average rate of movement should respond to changes in the frequency distribution of patch-types and how they should covary. We further compare the response of optimal and non-plastic foragers. We find that the initial pattern of patch exploitation in a habitat, characterized by the regression slope of patch yields over residence times, can help predict the qualitative responses of fitness and movement rate following habitat conversion. We also find that for some habitat conversion patterns, optimal and non-plastic foragers exhibit qualitatively different responses, and that adaptive foragers can have opposite responses in the short- and long-term following habitat conversion. We suggest taking into account behavioral responses may help better understand the ecological consequences of habitat conversion.
KeywordsBehaviour Fitness Marginal value theorem Movement Patchy habitats Theory
This work was supported by INRA and Université Côte d’Azur (IDEX JEDI).
Compliance with Ethical Standards
Conflict of interests
The authors declare that they have no conflicts of interest.
- Arditi R, Dacorogna B (1988) Optimal foraging on arbitrary food distributions and the definition of habitat patches. Am Nat: 837–846Google Scholar
- Calcagno V (2018) The marginal value theorem in a nutshell. In: Fath BD (ed) Encyclopedia of ecology. 2nd edn. OxfordGoogle Scholar
- Calcagno V, Grognard F, Hamelin FM, Wajnberg É, Mailleret L (2014a) The functional response predicts the effect of resource distribution on the optimal movement rate of consumers. Ecol Lett 17(12):1570–1579Google Scholar
- Calcagno V, Mailleret L, Wajnberg É, Grognard F (2014b) How optimal foragers should respond to habitat changes: a reanalysis of the marginal value theorem. J Math Biol 69(5):1237– 1265Google Scholar
- Charnov EL, Orians GH (1973) Optimal foraging: some theoretical explorations. unpublishedGoogle Scholar
- Mouquet N, Gravel D, Massol F, Calcagno V (2012) Extending the concept of keystone species to communities and ecosystems. Ecol LettGoogle Scholar
- Stephens D, Krebs J (1986) Foraging theory. Princeton University Press, PrincetonGoogle Scholar
- Turchin P (1998) Quantitative analysis of movement. Sinauer assoc. Sunderland (mass.)Google Scholar