How to measure top-down vs. bottom-up effects: A new population metric and its calibration on Daphnia

L. Polishchuk, J. Vijverberg, D.A. Voronov, W.M. Mooij

Onderzoeksoutput: Bijdrage aan wetenschappelijk tijdschrift/periodieke uitgaveArtikelWetenschappelijkpeer review

1 Downloads (Pure)


Research on the role of top–down (predation) and bottom–up (food) effects in food webs has led to the understanding that the variability of these effects in space and time is a fundamental feature of natural systems. Consequently, our measurement tools must allow us to evaluate the effects from a dynamical perspective. A population-dynamics approach may be appropriate to the task. More specifically, because food and predators both affect birth rate, birth rate dynamics may be a key to understanding their impact on the population of interest. Based on the Edmondson–Paloheimo model for birth rate, we propose a new population metric to assess the relative strength of top–down vs bottom–up effects. The metric is the ratio of contributions of changes in proportion of adults and fecundity to change in birth rate. Proportion of adults reflects a top–down effect (predators are assumed to be size-selective), fecundity reflects a bottom–up effect, and birth rate appears as a common currency with which to compare the former and the latter. Using microcosm experiments and computer simulations on the cladoceran Daphnia, we calibrate the metric and show that, in both types of tests, the ratio of contributions is typically 0.5–0.7 under a strong bottom–up effect and 2.0–2.2 under a strong top–down effect. This provides experimental evidence that the ratio of contributions may allow one to distinguish a strong top–down effect from a strong bottom–up effect.
Originele taal-2Engels
Pagina's (van-tot)1177-1186
Nummer van het tijdschrift8
StatusGepubliceerd - 2013


Duik in de onderzoeksthema's van 'How to measure top-down vs. bottom-up effects: A new population metric and its calibration on Daphnia'. Samen vormen ze een unieke vingerafdruk.

Citeer dit