1. Evolution in the context of DEB theory
Bas Kooijman
Dept theoretical biology
Vrije Universiteit Amsterdam
Wimereu, 2011/06/14

2. Mouse goes preying 2.1c On the island Gough,
the house mouse Mus musculus
preys on chicks of seabirds,
Tristan albatross Diomedea dabbenena
Atlantic petrel Pterodroma incerta
The bird weights are 250 
the mouse weight of 40 g,
Mice typically weigh 15 g
99% of these bird species
breed on Gough and are
now threatened with extinction

3. Dwarfing in Platyrrhini 8.1.2
Cebidae
130 g
Saimiri g
Saguinus g g g g g
3500 g
Callimico
Callitrix
Evolutionary dwarfing occurred within the Cebidae where new groups splitted off of smaller body size and larger distance to center-Amazonia.
Cebus, Saimiri and Aotus are relatively big and occur in center-Amazonia
Saguinus, Leontopithecus and Callimico split off, are smaller and occur at the border of center Amazonia
Callithrix, Mico and Cebuella followed, are even smaller and outside center Amazonia on the slopes of the Andes
This dwarfing is supposed to be related to food availability.
DEB theory suggests the same explanation for Bergmann’s rule that max body size in a taxon increases from the equator to the poles.
Bergmann’s rule does not apply here, but DEB’s explanation does.
Cebuella
Leontopithecus
MYA
Mico
Aotus
24.8
20.2
Perelman et al 2011
Plos Genetics 7, 3, e
Cebus

4. Altricial & Precocial Finfoots 2.5.2e
Heliornis fulica
American finfoot
Podica senegalensis,
African finfoot
Heliopais personata,
Asian finfoot
Most bird-families are either altricial or precocial, but the 3-species family of finfoots (Heliornithidae) have both.
This illustrates the evolutionary adaptability of the trait.
African and Asian finfoots are precocial, but American finfoots (also called sungrebes) are born altricial, blind without feathers.
The male sungrebe (lower left) has a pouch under each wing, in which he can carry the young, even in flight; they typically have 3 or 4 young.
Sungrebes have an very short incubation time for their size (130 g) of 10 – 11 days; both sexes share breeding in a nest in the vegetation above water.
The eggs are 28  20 mm, so they weigh about 6 g.
In African finfoots (338 – 879 g) only the females breeds her 2 eggs; the young leave the nest after a few days.
Finfoots resemble grebes and can also dive very well, but don’t do that for collecting food, which is a variety of insects, spiders, molluscs, fish, frogs etc.

5. Central Metabolism 3.8.2b
source
polymers
monomers
waste/source

6. Evolution of central metabolism 10.2.1
in prokaryotes (= bacteria)
3.8 Ga
2.7 Ga
i = inverse
ACS = acetyl-CoA Synthase pathway
PP = Pentose Phosphate cycle
TCA = TriCarboxylic Acid cycle
RC = Respiratory Chain
Gly = Glycolysis
Kooijman, Hengeveld 2005

7. Evolution of DEB systems 10.3
variable
structure
composition
strong
homeostasis
for structure
internalisation of
maintenance as
demand process
delay of use of
internal substrates
increase of
maintenance costs
installation of
maturation program 1 2 3 4 5 6
prokaryotes 7 9
plants
This scheme presents an evolutionary scenario for the metabolic organisation of an individual.
Only 2 of several reserves are shown.
Stacked dots (upper left) represent sloppy coupling between the various structural components
1: originally, strong homeostasis hardly applied and the various compounds from structure where formed from substrates, possibly will little transformation
2: the development of homeostasis comes with stoichiometric constraints on the uptake of substrates
3: since growth can only occur if all required substrates are present, and substrate concentrations vary in time, reserves develop, originally by delaying the processing of internalised substrates.
4: the increase of efficiency of protein-mediated substrate uptake involves maintenance costs.
The increased uptake efficiency increases the reserve pools, and the necessity developed to convert and store reserve (in polymers, or nutrients in vacuoles)
5: since substrates vary in concentration and are continuously required for maintenance, the payment of maintenance is internalised and done from mobilised reserve
6: size control comes with a need for a maturation program; defense systems are fuelled from maturity maintenance
Under starvation conditions, where maturity maintenance cannot be paid, rejuvenation occurs, and the hazard rate is increased.
Failure of paying somatic maintenance leads to shrinking of structure, but is a threshold is exceeded, death is instantaneous.
This situation applies to modern bacteria and many protoctists
7: The animal-line of development, which feed on other organisms, increased homeostasis and the number of reserves shrinks to 1.
8: Reproduction evolved and the juvenile stage gave rise to an embryo (no assimilation) and an adult stage (no maturation, but reproduction)
9: The plant-line of development increased the number of structures (roots and shoots), with specialised assimilation tasks
Reproduction evolved also here, typically in the shoot, and translocation evolved: a fraction of mobilised reserve is allocated to the other structure. 8
animals
Kooijman & Troost 2007
Biol Rev, 82, 1-30
reproduction
juvenile  embryo + adult
strong homeostasis
for reserve
specialization
of structure

8. Evolution of DEB systems 10.3a
Start: variable biomass composition, passive uptake
Strong homeostasis  stoichiometric constraints
Reserves: delay of use of internalised substrates  storage, weak homeostasis
Maintenance requirements: turnover (e.g. active uptake by carriers), regulation
Maintenance from reserve instead of substrate; increase reserve capacity
Control of morphology via maturation; -rule  cell cycle
Diversification of assimilation (litho-  photo-  heterotrophy)
Eukaryotisation: heterotrophic start; unique event?
Syntrophy & compartmentalisation: mitochondria, genome reorganisation
Phagocytosis, plastids (acquisition of phototrophy)
Animal trajectory: biotrophy
Reduction of number of reserves
Emergence of life stages
Further increase of maintenance costs
Further increase of reserve capacity
Socialisation
Supply  demand systems
Plant trajectory: site fixation
Differentiation of root and shoot
Emergence of life stages
Increase of metabolic flexibility (draught)
Nutrient acquisition via transpiration
Symbioses with animals, fungi, bacteria
(e.g. re-mineralisation leaf litter, pollination)

9. Symbiogenesis 10.4g
2.7 Ga
2.1 Ga
1.27 Ga
phagocytosis

10. Symbiogenesis 10.4p
symbioses: fundamental organisation of life based on syntrophy
ranges from weak to strong interactions; basis of biodiversity
symbiogenesis: evolution of eukaryotes (mitochondria, plastids)
DEB model is closed under symbiogenesis:
it is possible to model symbiogenesis of two initially independently
living populations that follow the DEB rules by incremental changes
of parameter values such that a single population emerges that
again follows the DEB rules
essential property for models that apply to all organisms
Kooijman, Auger, Poggiale, Kooi 2003
Quantitative steps in symbiogenesis and the evolution of homeostasis
Biological Reviews 78:

11. Symbiosis 10.4m substrate product
Very few life forms can exist without the help of other life forms.
Mutual syntrophy, the you of pruducts as substrates dominates co-existence at all levels of organisation.
Think of the interaction between metabolic modules within a unicellular, between organs in a multicelluar, between individuals or populations.

12. Symbiosis 10.4n substrate substrate
The use each other products affects the role of the original substrate.
Stoichiometric coupling between the use of substrate and product is an important route to homeostasis:
the ability to run metabolism independently from environmental conditions (less than perfect, of course)

13. Steps in symbiogenesis 10.4o
Free-living, homogeneous
Free-living, clustering
Internalization
The rules of DEB theory allow for a unique property:
individuals that follow DEB-rules can merge to a new single individual incrementally such that the merge individual again follows the DEB rules.
An individual can also split up this way.
Merging and splitting have been frequent in evolution.
This metabolic flexibility is possible due to basic simplicity in the organisation.
Rules for Synthesising Unit (SU) dynamics play an important role here:
SUs are generalised enzymes that follow the rules of enzyme kinetics with 2 modifications:
1) transformation is not controlled by substrate concentrations, but the arrival rates of substrate molecules to SUs
2) intra-cellular transport processes prevent the conversion of products to substrates;
the transformation from substrates to products is unidirectional
The processes of merging and splitting imposes constraints of organisation.
This has similarities for firms as an individual in economy.
A group in Lisbon is exploring the interrelationships between biological and economics systems in the context of DEB theory.
Structures merge
Reserves merge

14. Syntrophy 9.1.2 Coupling hydrogen & methane production
energy generation aspect at aerobic/anaerobic interface
ethanol
acetate
dihydrogen
dihydrogen
bicarbonate
methane
Total:
methane hydrates
>300 m deep, < 8C
linked with nutrient supply

15. Allocation to soma 10.5.2 Frequency distribution of κ
pop growth rate, d-1
max reprod rate, #d-1
survivor function κ κ κ
Frequency distribution of κ
among species in the
add_my_pet collection:
Mean κ = 0.75,
but optimum is κ = 0.5
Lika et al 2011
J. Sea Res, to appear