Current research on DEB theoryBas Kooijman

Dept theoretical biologyVrije Universiteit Amsterdam

Bas@bio.vu.nlhttp://www.bio.vu.nl/thb/

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 KooijmanDept theoretical biology

Vrije Universiteit AmsterdamBas@bio.vu.nl

http://www.bio.vu.nl/thb/

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- maturitymaintenance

maturityoffspring

maturationreproduction

Modes of action of toxicants

food faecesassimilation

reserve

feeding defecation

structurestructure

somaticmaintenance

growth

assimilation

maintenance costs

growth costs

reproduction costs

hazard to embryo

u

tumourtumour

maint tumour induction6

6

endocr. disruption7

7

lethal effects: hazard rateMode of action affectstranslation 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 - IBM1980

1990

2000

Daphniaecotox

application

NECs

ISO/OECD

embryos

body sizescaling

morphdynamicsindirect

calorimetry

food chains

SynthesizingUnits

multivarplants

adaptationtumour

induction

von Foerster

epidemiolapplications

bifurcationanalysis

Globalbif-analysis

integralformulations

adaptive dynamics

ecosystem Self-orginazation

numericalmethods

symbioses

ecosystemdynamics

molecularorganisation

DEB 1

DEB 2

DEBtox 1

organfunction

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

spac

e

Space-time scales

When changing the space-time scale, new processes will become important other will become less importantModels 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 year author model year author model

1780 Lavoisier multiple regression of heat against mineral fluxes

1950 Emerson cube root growth of bacterial colonies

1825 Gompertz Survival probability for aging 1951 Huggett & Widdas foetal growth

1889 Arrhenius temperature dependence of physiological rates

1951 Weibull survival probability for aging

1891 Huxley allometric growth of body parts 1955 Best diffusion limitation of uptake

1902 Henri Michaelis--Menten kinetics 1957 Smith embryonic respiration

1905 Blackman bilinear functional response 1959 Leudeking & Piret microbial product formation

1910 Hill Cooperative binding 1959 Holling hyperbolic functional response

1920 Pütter von Bertalanffy growth of individuals

1962 Marr & Pirt maintenance in yields of biomass

1927 Pearl logistic population growth 1973 Droop reserve (cell quota) dynamics

1928 Fisher & Tippitt

Weibull aging 1974 Rahn & Ar water loss in bird eggs

1932 Kleiber respiration scales with body weight3/ 4

1975 Hungate digestion

1932 Mayneord cube root growth of tumours 1977 Beer & 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

O2

cons

umpt

ion,

μl/h

1/yi

eld,

mm

ol g

luco

se/

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 2007http://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/

Cambridge Univ Press 2000

Audience: thank you for your attention

38 participants in 2007Late registration via Bas@bio.vu.nl