Allometric functional response model: body masses constrain interaction strengths

• Published in: The Journal of animal ecology Vol. 79; no. 1; pp. 249 - 256
• Main Authors: Vucic-Pestic, Olivera, Rall, Björn C, Kalinkat, Gregor, Brose, Ulrich
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.01.2010; Blackwell Publishing; Blackwell Publishing Ltd; Blackwell
• Subjects: Animal and plant ecology; Animal ecology; Animal physiology; Animal, plant and microbial ecology; Animals; Araneae; attack rate; Beetles; Biological and medical sciences; Body Weight - physiology; body-mass ratio; Coleoptera - physiology; Drosophila - physiology; Ecological modeling; Ecology; Food Chain; Food chains; food webs and predator-prey interactions; Functional responses; Fundamental and applied biological sciences. Psychology; General aspects; handling time; hill exponent; Insects; Marine ecology; Mass ratio; metabolic theory; Models, Biological; Nonlinear systems; optimal foraging; per capita consumption rate; Population Ecology; Predation; Predators; Predatory Behavior - physiology; Spiders; Spiders - physiology; Predator prey relation; attack rate; Hill; hill exponent; Functional response; Theory; Interaction; Body weight; handling time; Allometry; metabolic theory; body-mass ratio; Food web; Food intake; per capita consumption rate; food webs and predator-prey interactions; Models; Ratio; Optimal foraging
• ISSN: 0021-8790; 1365-2656
• DOI: 10.1111/j.1365-2656.2009.01622.x

1. Functional responses quantify the per capita consumption rates of predators depending on prey density. The parameters of these nonlinear interaction strength models were recently used as successful proxies for predicting population dynamics, food-web topology and stability. 2. This study addressed systematic effects of predator and prey body masses on the functional response parameters handling time, instantaneous search coefficient (attack coefficient) and a scaling exponent converting type II into type III functional responses. To fully explore the possible combinations of predator and prey body masses, we studied the functional responses of 13 predator species (ground beetles and wolf spiders) on one small and one large prey resulting in 26 functional responses. 3. We found (i) a power-law decrease of handling time with predator mass with an exponent of -0·94; (ii) an increase of handling time with prey mass (power-law with an exponent of 0·83, but only three prey sizes were included); (iii) a hump-shaped relationship between instantaneous search coefficients and predator-prey body-mass ratios; and (iv) low scaling exponents for low predator-prey body mass ratios in contrast to high scaling exponents for high predator-prey body-mass ratios. 4. These scaling relationships suggest that nonlinear interaction strengths can be predicted by knowledge of predator and prey body masses. Our results imply that predators of intermediate size impose stronger per capita top-down interaction strengths on a prey than smaller or larger predators. Moreover, the stability of population and food-web dynamics should increase with increasing body-mass ratios in consequence of increases in the scaling exponents. 5. Integrating these scaling relationships into population models will allow predicting energy fluxes, food-web structures and the distribution of interaction strengths across food web links based on knowledge of the species' body masses.