TY  - JOUR
A1  - Martin, Benjamin T.
A1  - Jager, Tjalling
A1  - Nisbet, Roger M.
A1  - Preuss, Thomas G.
A1  - Grimm, Volker
T1  - Predicting population dynamics from the properties of individuals - a cross-level test of dynamic energy budget theory
JF  - The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences
N2  - Individual-based models (IBMs) are increasingly used to link the dynamics of individuals to higher levels of biological organization. Still, many IBMs are data hungry, species specific, and time-consuming to develop and analyze. Many of these issues would be resolved by using general theories of individual dynamics as the basis for IBMs. While such theories have frequently been examined at the individual level, few cross-level tests exist that also try to predict population dynamics. Here we performed a cross-level test of dynamic energy budget (DEB) theory by parameterizing an individual-based model using individual-level data of the water flea, Daphnia magna, and comparing the emerging population dynamics to independent data from population experiments. We found that DEB theory successfully predicted population growth rates and peak densities but failed to capture the decline phase. Further assumptions on food-dependent mortality of juveniles were needed to capture the population dynamics after the initial population peak. The resulting model then predicted, without further calibration, characteristic switches between small-and large-amplitude cycles, which have been observed for Daphnia. We conclude that cross-level tests help detect gaps in current individual-level theories and ultimately will lead to theory development and the establishment of a generic basis for individual-based models and ecology.
KW  - population dynamics
KW  - dynamic energy budget theory
KW  - bioenergetics
KW  - individual-based model
Y1  - 2013
U6  - https://doi.org/10.1086/669904
SN  - 0003-0147
VL  - 181
IS  - 4
SP  - 506
EP  - 519
PB  - Univ. of Chicago Press
CY  - Chicago
ER  - 
TY  - JOUR
A1  - Bailleul, Frederic
A1  - Grimm, Volker
A1  - Chion, Clement
A1  - Hammill, Mike
T1  - Modeling implications of food resource aggregation on animal migration phenology
JF  - Ecology and evolution
N2  - The distribution of poikilotherms is determined by the thermal structure of the marine environment that they are exposed to. Recent research has indicated that changes in migration phenology of beluga whales in the Arctic are triggered by changes in the thermal structure of the marine environment in their summering area. If sea temperatures reflect the spatial distribution of food resources, then changes in the thermal regime will affect how homogeneous or clumped food is distributed. We explore, by individual-based modelling, the hypothesis that changes in migration phenology are not necessarily or exclusively triggered by changes in food abundance, but also by changes in the spatial aggregation of food. We found that the level of food aggregation can significantly affect the relationship between the timing of the start of migration to the winter grounds and the total prey capture of individuals. Our approach strongly indicates that changes in the spatial distribution of food resources should be considered for understanding and quantitatively predicting changes in the phenology of animal migration.
KW  - Animal migration
KW  - food structuring
KW  - global change
KW  - individual-based model
KW  - polar environment
Y1  - 2013
U6  - https://doi.org/10.1002/ece3.656
SN  - 2045-7758
VL  - 3
IS  - 8
SP  - 2535
EP  - 2546
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -