Standard DEB model

Download Standard DEB model

Post on 06-Jan-2016

22 views

Category:

Documents

1 download

Embed Size (px)

DESCRIPTION

defecation. feeding. food. faeces. assimilation. reserve. somatic maintenance. maturity maintenance. . 1- . maturation reproduction. growth. maturity offspring. structure. Standard DEB model. Feeding. Feeding has two aspects - PowerPoint PPT Presentation

TRANSCRIPT

  • Standard DEB model

  • FeedingFeeding has two aspects disappearance of food (for food dynamics): JX,F appearance of substrate for metabolic processing: JX,A= JX,F

    Faeces cannot come out of an animal, because it was never in it is treated as a product that is linked to assimilation: JP,F= yPX JX,F

  • Feedingtimetimebinding prob.binding prob.fast SUslow SUarrival events of food items00Busy periods not only include handling but also digestion and other metabolic processing

  • AssimilationDefinition:Conversion of substrate(s) (food, nutrients, light) into reserve(s)Energy to fuel conversion is extracted from substratesImplies: products associated with assimilation (e.g. faeces, CO2)

    Depends on: substrate availability structural (fixed part of) surface area (e.g. surface area of gut)

    Consequence of strong homeostasis:Fixed conversion efficiency for fixed composition of substrate

    However, biomass composition is not fixed many species feed on biomass

  • Assimilationfood densitysaturation constantstructural volumereserveyield of E on X

  • Reserve dynamics & allocationIncrease: assimilation structural surface areaDecrease: mobilisation reserve-structure interface Change in reserve density structural length-1

    Reserve dynamics follows from weak homeostasis of biomass = structure + reserve

    -rule for allocation to soma: constant fraction of mobilisation rate

  • Reserve dynamicstime, hPHB density, mol/molin starving active sludgeData fromBeun, 2001

  • Yield of biomass on substrate1/spec growth rate, h-1Data fromRussel & Cook, 1995maintenancereserve

  • -rule for allocationAge, dAge, dLength, mmLength, mmCum # of youngLength, mmIngestion rate, 105 cells/hO2 consumption, g/h large part of adult budget to reproduction in daphnids puberty at 2.5 mm No change in ingest., resp., or growth Where do resources for reprod. come from? Or: What is fate of resources in juveniles?Respiration Ingestion Reproduction Growth:Von Bertalanffy

  • Somatic maintenanceDefinition of maintenance (somatic and maturity):Collection of processes not associated with net productionOverall effect: reserve excreted products (e.g. CO2, NH3)

    Somatic maintenance comprises: protein turnover (synthesis, but no net synthesis) maintaining conc gradients across membranes (proton leak) maintaining defence systems (immune system) (some) product formation (leaves, hairs, skin flakes, moults) movement (usually less than 10% of maintenance costs)

    Somatic maintenance costs paid from flux JE,C: structural volume (mosts costs), pM surface area (specific costs: heating, osmo-regulation), pT

  • Maturity maintenanceDefinition of maturity maintenance:Collection of processes required to maintain current state of maturity

    Maturity maintenance costs paid from flux (1-)JE,C: maturity constant in adults (even if they grow)

    Else: size at transition depends on history of food intake

  • Maintenance first0number of daphnids106 cells.day-130020010001206030126max number of daphnids303540030020010081115182124283237time, d30106 cells.day-1Chlorella-fed batch cultures of Daphnia magna, 20Cneonates at 0 d: 10winter eggs at 37 d: 0, 0, 1, 3, 1, 38Kooijman, 1985 Toxicity at population level. In: Cairns, J. (ed) Multispecies toxicity testing. Pergamon Press, New York, pp 143 - 164Maitenance requirements:6 cells.sec-1.daphnid-1

  • GrowthDefinition:Conversion of reserve(s) into structure(s)Energy to fuel conversion is extracted from reserve(s)Implies: products associated with growth (e.g. CO2, NH3)

    Allocation to growth:

    Consequence of strong homeostasis:Fixed conversion efficiency

  • Mixtures of V0 & V1 morphsvolume, m3volume, m3volume, m3hyphal length, mmtime, htime, mintime, mintime, minFusarium = 0Trinci 1990Bacillus = 0.2Collins & Richmond 1962Escherichia = 0.28Kubitschek 1990Streptococcus = 0.6Mitchison 1961

  • Growth

  • Growth at constant foodtime, dultimate length, mmlength, mmVon Bert growth rate -1, dVon Bertalanffy growth curve:

  • Mouse goes preying 2.1cOn the island Gough, the house mouse Mus musculus preys on chicks of seabirds, Tristan albatross Diomedea dabbenenaAtlantic petrel Pterodroma incerta

    The bird weights are 250 the mouse weight of 40 g,Mice typically weigh 15 g

    99% of these bird speciesbreed on Gough and are now threatened with extinction

  • MetamorphosisThe larval malphigian tubes are clearly visible in this emerging cicadaThey resemble a fractally-branching space-filling tubing system, according to Jim Brown, but judge yourself .Java, Nov 2007

  • ReproductionDefinition:Conversion of adult reserve(s) into embryonic reserve(s)Energy to fuel conversion is extracted from reserve(s)Implies: products associated with reproduction (e.g. CO2, NH3)

    Allocation to reproduction in adults:

    Allocation per time increment is infinitesimally smallWe therefore need a buffer with buffer-handling rules for egg prod (no buffer required in case of placental mode)

    Strong homeostasis: Fixed conversion efficiencyWeak homeostasis: Reserve density at birth equals that of motherReproduction rate: follows from maintenance + growth costs, given amounts of structure and reserve at birth

  • Reproduction at constant foodlength, mmlength, mm103 eggs103 eggsGobius paganellusData Miller, 1961Rana esculentaData Gnther, 1990

  • Maturity & its maintenanceDEB implementation is motivated by 4 observations 1 Contrary to age, volume at birth or puberty hardly depends on food density. So stage transitions cannot be linked to age. 2 Some species continue growing after puberty. Other species, such as birds, only reproduce well after the growth period. So stage transitions cannot be linked to size.

    3 Total cumulative energy investment in development at any given size of the individual depends on food density; this can be removed by allowing for maturity maintenance. 4 Ultimate reproduction rate is a continuous function of food density This demonstrates the existence of maturity maintenance.

  • Maintenance ratio 2.5.3b

  • Extremes in relative maturity at birth in mammals 2.5.2aOmmatophoca rossii (Ross Seal) 1.7-2.1 m, 129-216 kg 1.3-2.2 m, 159-204 kgAt birth: 1 m, 16.5 kg; ab = 270 d

    Didelphus marsupiales (Am opossum) , 0.5 + 0.5 m, 6.5 kgAt birth:

  • Extremes in relative maturity at birth in birds 2.5.2bApteryx australis (kiwi) 2.2 kg; 2.8 kgEgg: 128 cm, 550 g; ab = 63-92 dCuculus canorus (cuckoo) , 115 gEgg: 3.3 g; ab = 12 d

  • Extremes in relative maturity at birth in fish 2.5.2cLatimeria chalumnae (coelacanth) , 1.9 m, 90 kgEgg: 325 gAt birth: 30 cm; ab = 395 dFeeds on fishMola mola (ocean sunfish) , 4 m, 1500 (till 2300) kgEgg: 3 1010 eggs in bufferAt birth: 1.84 mm g; ab = ? dFeeds on jellfish & combjellies

  • Short juvenile period 2.5.2dHemicentetes semispinosus (streaked tenrec ) ap - ab = 35 dLemmus lemmus (Norway lemming ) ap - ab = 12 d

  • Embryonic developmenttime, dtime, dweight, gO2 consumption, ml/h;: scaled timel : scaled lengthe: scaled reserve densityg: energy investment ratioCrocodylus johnstoni,Data from Whitehead 1987yolkembryo

  • Diapauze 2.6.2cseeds of heather Calluna vulgaris can germinate after 100 year

  • Foetal developmentweight, gtime, dMus musculusFoetes develop like eggs, but rate not restricted by reserve (because supply during development)Reserve of embryo added at birth Initiation of development can be delayed by implantation egg cellNutritional condition of mother only affects foetus in extreme situations Data: MacDowell et al 1927

  • High age at birth 2.6.2fSphenodon punctatus (tuatara)Adult: 45-60 cm, Wm = 0.5 1 kg, larger than 10 eggs/litter, life span 60 - >100 aBody temp 20-25 C, ap = 20 a, Wb = 4 g, ab = 450 d.

  • ReproductionDefinition:Conversion of adult reserve(s) into embryonic reserve(s)Energy to fuel conversion is extracted from reserve(s)Implies: products associated with reproduction (e.g. CO2, NH3)

    Allocation to reproduction in adults:

    Allocation per time increment is infinitesimally smallWe therefore need a buffer with buffer-handling rules for egg prod (no buffer required in case of placental mode)

    Strong homeostasis: Fixed conversion efficiencyWeak homeostasis: Reserve density at birth equals that of motherReproduction rate: follows from maintenance + growth costs, given amounts of structure and reserve at birth

  • Reproduction at constant foodlength, mmlength, mm103 eggs103 eggsGobius paganellusData Miller, 1961Rana esculentaData Gnther, 1990

  • General assumptions State variables: structural body mass & reserve & maturity structure reserve do not change in composition; maturity is information Food is converted into faeces Assimilates derived from food are added to reserves, which fuel all other metabolic processes Three categories of processes: Assimilation: synthesis of (embryonic) reserves Dissipation: no synthesis of biomass Growth: synthesis of structural body mass Product formation: included in these processes (overheads) Basic life stage patterns dividers (correspond with juvenile stage) reproducers embryo (no feeding initial structural body mass is negligibly small initial amount of reserves is substantial) juvenile (feeding, but no reproduction) adult (feeding & male/female reproduction)

  • Specific assumptions Reserve density hatchling = mother at egg f