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Predictive power of food web models based on body size decreases with trophic complexity
Author(s) -
Jonsson Tomas,
Kaartinen Riikka,
Jonsson Mattias,
Bommarco Riccardo
Publication year - 2018
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.12938
Subject(s) - trophic level , food web , guild , intraguild predation , ecology , predictive power , microcosm , biology , predation , predator , physics , quantum mechanics , habitat
Food web models parameterised using body size show promise to predict trophic interaction strengths ( IS ) and abundance dynamics. However, this remains to be rigorously tested in food webs beyond simple trophic modules, where indirect and intraguild interactions could be important and driven by traits other than body size. We systematically varied predator body size, guild composition and richness in microcosm insect webs and compared experimental outcomes with predictions of IS from models with allometrically scaled parameters. Body size was a strong predictor of IS in simple modules ( r 2 = 0.92), but with increasing complexity the predictive power decreased, with model IS being consistently overestimated. We quantify the strength of observed trophic interaction modifications, partition this into density‐mediated vs. behaviour‐mediated indirect effects and show that model shortcomings in predicting IS is related to the size of behaviour‐mediated effects. Our findings encourage development of dynamical food web models explicitly including and exploring indirect mechanisms.