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Current research on DEB theory

This article discusses the current research on the Dynamic Energy Budget (DEB) theory and its application to quantifying the effects of chemical compounds on daphnid reproduction. It explores the relationship between reproduction, energy budget, and the environment, and highlights the importance of DEB theory in understanding individual, population, and ecosystem dynamics. The article also discusses the modes of action of toxicants and the implications for predicting ecological impacts. Overall, this research contributes to our understanding of the metabolic organization of organisms and its applications in various fields.

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Current research on DEB theory

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  1. Current research on DEB theory Bas Kooijman Dept theoretical biology Vrije Universiteit Amsterdam Bas@bio.vu.nl http://www.bio.vu.nl/thb/ Marseille, 2007/01/17

  2. Historic roots Aug 1979 • Two questions: • How should we quantify effects of • chemical compounds on reproduction of daphnids? • reproduction  energy budget • How bad is it for the environment if daphnid reproduction • is a bit reduced due to toxic stress? • individual  population  ecosystem • prediction outside observed range: first principles

  3. assimilation  maintenance costs defecation feeding food faeces growth costs assimilation reproduction costs reserve  hazard to embryo somatic maintenance  7 maturity maintenance  1-  maint tumour induction 6 maturation reproduction u endocr. disruption growth 7  lethal effects: hazard rate Mode of action affects translation to pop level 8 maturity offspring structure tumour 6 Modes of action of toxicants 6.4

  4. Individual  Ecosystem • population dynamics is derived from • properties of individuals + interactions between them • evolution according to Darwin: • variation between individuals + selection • material and energy balances: • most easy for individuals • individuals are survival machines of life

  5. DEB – ontogeny - IBM Daphnia von Foerster ecotox application embryos 1980 body size scaling epidemiol applications morph dynamics indirect calorimetry bifurcation analysis micro’s numerical methods food chains 1990 Global bif-analysis aging DEB 1 Synthesizing Units NECs integral formulations DEBtox 1 multivar plants adaptive dynamics tumour induction ecosystem dynamics 2000 DEB 2 adaptation organ function symbioses ecosystem Self-orginazation ISO/OECD molecular organisation

  6. Shift in emphasis From concrete questions about individuals quantification of properties of individuals + consequences To metabolic organisation at various levels relationships between levels of organisation

  7. Space-time scales 1.2.1 Each process has its characteristic domain of space-time scales system earth space ecosystem population When changing the space-time scale, new processes will become important other will become less important Individuals are special because of straightforward energy/mass balances individual cell time molecule

  8. Dynamic Energy Budget theory for metabolic organization • links levels of organization • molecules, cells, individuals, populations, ecosystems • scales in space and time: scale separation • interplay between biology, mathematics, • physics, chemistry, earth system sciences • framework of general systems theory • quantitative; first principles only • equivalent of theoretical physics • fundamental to biology; many practical applications • (bio)production, medicine, (eco)toxicity, climate change

  9. Standard DEB model Isomorph with 1 reserve and 1 structure that feeds of 1 type of food and has 3 life stages (embryo, juvenile, adult) • Extensions: • more types of food and food qualities • more types of reserve • more types of structure • changes in morphology • different number of life stages

  10. DEB theory is axiomatic, based on mechanisms not meant to glue empirical models Since many empirical models turn out to be special cases of DEB theory the data behind these models support DEB theory This makes DEB theory very well tested against data Empirical special cases of DEB

  11. DEB theory reveals unexpected links Streptococcus O2 consumption, μl/h 1/yield, mmol glucose/ mg cells Daphnia 1/spec growth rate, 1/h Length, mm respiration  length in individual animals & yield  growth in pop of prokaryotes have a lot in common, as revealed by DEB theory Reserve plays an important role in both relationships, but you need DEB theory to see why and how

  12. DEB tele course 2007 Cambridge Univ Press 2000 http://www.bio.vu.nl/thb/deb/ Free of financial costs; some 200 h effort investment Feb-April 2007; target audience: PhD students We encourage participation in groups that organize local meetings weekly Participants of DEB tele course 2005 created AQUAdeb: special issue of J. Sea Res. 2006 on DEB applications to bivalves Software package DEBtool for Octave/ Matlab freely downloadable Slides of this presentation will be downloadable from http://www.bio.vu.nl/thb/users/bas/lectures/ Audience: thank you for your attention

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