Current research on DEB theory Bas Kooijman Dept theoretical biology Vrije Universiteit Amsterdam Lisboa, 2007/02/07
Current research on DEB theory Lisboa, 2007/02/07 Contents : What is DEB theory? Historical roots Scales in time & space Empirical basis Unexpected links Applications of DEB theory Bas Kooijman Dept theoretical biology Vrije Universiteit Amsterdam
Dynamic Energy Budget theory consists of a set of consistent and coherent assumptions uses framework of general systems theory links levels of organization scales in space and time: scale separation quantitative; first principles only equivalent of theoretical physics interplay between biology, mathematics, physics, chemistry, earth system sciences fundamental to biology; many practical applications for metabolic organization
Historical 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
1- maturity maintenance maturity offspring maturation reproduction Modes of action of toxicants foodfaeces assimilation reserve feeding defecation structure somatic maintenance growth assimilation maintenance costs growth costs reproduction costs hazard to embryo uu tumour maint tumour induction 6 6 endocr. disruption 7 7 lethal effects: hazard rate Mode of action affects translation to pop level 8
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 the survival machines of life
DEB – ontogeny - IBM Daphnia ecotox application NECs ISO/OECD embryos body size scaling morph dynamics indirect calorimetry food chains Synthesizing Units multivar plants adaptation tumour induction von Foerster epidemiol applications bifurcation analysis Global bif-analysis integral formulations adaptive dynamics ecosystem Self-orginazation numerical methods symbioses ecosystem dynamics molecular organisation DEB 1 DEB 2 DEBtox 1 organ function aging micro’s
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
molecule cell individual population ecosystem system earth time space Space-time scales When changing the space-time scale, new processes will become important other will become less important Models with many variables & parameters hardly contribute to insight Each process has its characteristic domain of space-time scales
Standard DEB model Isomorph with 1 reserve & 1 structure feeds on 1 type of food has 3 life stages (embryo, juvenile, adult) Extensions : more types of food and food qualities more types of reserve (autotrophs) more types of structure (organs, plants) changes in morphology different number of life stages
Empirical special cases of DEB yearauthormodelyearauthormodel 1780Lavoisier multiple regression of heat against mineral fluxes 1950Emerson cube root growth of bacterial colonies 1825Gompertz Survival probability for aging 1951Huggett & Widdas foetal growth 1889Arrhenius temperature dependence of physiological rates 1951Weibull survival probability for aging 1891Huxley allometric growth of body parts 1955Best diffusion limitation of uptake 1902Henri Michaelis--Menten kinetics 1957Smith embryonic respiration 1905Blackman bilinear functional response 1959Leudeking & Piret microbial product formation 1910Hill Cooperative binding 1959Holling hyperbolic functional response 1920Pütter von Bertalanffy growth of individuals 1962Marr & Pirt maintenance in yields of biomass 1927Pearl logistic population growth 1973Droop reserve (cell quota) dynamics 1928Fisher & Tippitt Weibull aging 1974Rahn & Ar water loss in bird eggs 1932Kleiber respiration scales with body weight 3/ Hungate digestion 1932Mayneord cube root growth of tumours 1977Beer & Anderson development of salmonid embryos 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 DEB theory reveals when to expect deviations from these empirical models
DEB theory reveals unexpected links Length, mm O 2 consumption, μl/h 1/yield, mmol glucose/ mg cells 1/spec growth rate, 1/h Daphnia Streptococcus 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
Applications of DEB theory bioproduction: agronomy, aquaculture, fisheries pest control biotechnology, sewage treatment, biodegradation (eco)toxicology, pharmacology medicine: cancer biology, obesity, nutrition biology global change: biogeochemical climate modeling conservation biology; biodiversity economy; sustainable development Fundamental knowledge of metabolic organisation has many practical applications
DEB tele course 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 on DEB applications to bivalves Software package DEBtool for Octave/ Matlab freely downloadable Slides of this presentation will be downloadable from Cambridge Univ Press 2000 Audience : thank you for your attention 38 participants in 2007 Late registration via