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LOCAL FORAGING AND LIMITED MOBILITY: DYNAMICS OF A SIZE‐STRUCTURED CONSUMER POPULATION
Author(s) -
van Kooten Tobias,
de Roos André M.,
Persson Lennart
Publication year - 2004
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/03-0304
Subject(s) - population size , population , competition (biology) , foraging , divergence (linguistics) , ecology , population model , econometrics , statistical physics , biology , economics , physics , demography , linguistics , philosophy , sociology
Size‐structured population models often exhibit single generation cycles, which are driven by scramble competition within a generation and size‐based competitive asymmetry among generations. These cycles are characterized by the dominance of a single cohort and thus by a high degree of synchronization of the individual life histories. The models, however, do not generally allow for divergence in size among individuals born at the same time. Size divergence may, for example, result from the stochasticity that arises due to local interactions between individuals and their environment and has been shown to affect the population dynamics within generations. We studied the effect of the size divergence that develops as a result of stochasticity over many generations, considering the full population dynamical feedback, including resource dynamics. The stochastic variation in our model was generated by local interactions of individuals with the environment. We varied the mobility of individuals, which regulated the strength of the local resource feedback on the consumers. We found that at very high mobility our model provided a good correspondence to similar but fully deterministic models, showing the single generation cycles typical for a size‐structured consumer–resource interaction. Intermediate levels of mobility had no notable effect on the dynamics of our model population. At very low mobility, the dynamics appeared to be strongly influenced by stochasticity. We showed that by superposition of the underlying deterministic dynamics and the stochasticity induced by local interactions we could fully understand the dynamics of the model. This finding led us to conclude that, while individual variability may have an impact on population structure and dynamics, it does not necessarily change the deterministic interactions that determine global population dynamics. More specifically, our study highlights the robustness of single generation cycles, showing that even at high levels of individual variability the population dynamics will intermittently exhibit patterns resembling these cycles.