Modelling Approaches Flashcards
Overview
1.why use /usefulness/build 2mechanistic modelling 1 .SIZE 3mechanistic modelling 2. Thermal PHYSIOLOGY 4Case study : Fisheries -single spp approach -multi spp approach -c trait based 5.Case study : Carbon cycle
why use 3
capture essence
inform us what is important in complex sysyste,
develop accurate predictions (for the future)
who said “all models are wrong but some are useful” and when?
George Box
1987
George Box - why use (b)
all models are a simplification of reality (ie rictionless pendum) - for wrong bit
some models are only a little bit wrong and can be useful in making accurate predictions
How to build (5)
increase complex of same basic
COMPETING models
select using Occam’s razor
select - competing model with FEWEST assumptions
NEED TO UNDERSTAND - mechanistic processes - and thus underlying pattern (in contrast to pheno)
what does a mechanistic model explain?
processes underlying an observed pattern
Example of different bio models
2
Ricker model 1954
Lotka Volterra
Ricker model equation?
N t+1 = N t e^r (1-Nt/K)
what do N T K r and through what mechanism in the Ricker model
N=pop size
T= time step
K=carrying capacity
r- growth rate
What about buikding models in terms of levels?
what are the 3 levels of organisation?
what 3 things to each include?
Need to build model for right level of organisation
Individual
1) metabolic rate
2) growth rate
3) temp rate
Interactions
consumer resource
competition
density depe
Community
top down regulation
bottom up regulation
trophic cascades
why use / usefulness / build overview? (5)
why (3) George box 1987 build (5) Occam's razor Mechanistic - Ricker - Lotka volterra levels + incorporate (AIC)
how do we incorporate the right level? and what is AIC?
1) agrees well wit hdata?
2) agrees best? (right mechanism for prediction?
3) model selection using Occam’s razor for example AIC
Akaike Information Criterion
- shows how much info a modle captures and its suitability for data
- Mechanistic modelling - importance of size overview (4)
magnitude difference
metabolic rate define - Kleiber’s Law
so… Damuth’s Law
Use?
Mechanistic modelling size
a) magnitude dif of ecosystem?
ecosystem can have 10- 20 orders of magnitude different in an ecosystem 10^-16 g to 10^3 g
Mehcnaistic modelling size
b)what is metabolic rate? / resting rate defines what?
rate of individual energy use (watts)
metabolic rate in retsings state (M) sets pace of life
M= M0 m b
(large organisms less of spring)
resting metabolic rate = Kleiber’s law 1947
c) Savage et al universal law?
Savage et al 2004
as mass increases
metabolic mass increases
so… what is Damuth’s law ?
Damuth’s law tells how population density is related to body size (mass).
It says that species with larger body sizes generally have lower average population densities.
More exactly, it states that the average density of a population decreases with body size at a power of approximately 3/4 the body mass (Damuth 1981, 1987, 1991).
Kleiber’s law?? wider
Kleiber’s law, named after Max Kleiber for his biology work in the early 1930s,
is the observation that, for the vast majority of animals, an animal’s metabolic rate scales to the ¾ power of the animal’s mass. Symbolically: if q₀ is the animal’s metabolic rate, and M the animal’s mass, then Kleiber’s law states that q₀ ~ M¾. Thus, over the same timespan, a cat having a mass 100 times that of a mouse will consume only about 32 times the energy the mouse uses.
kleibers law
animal’s metabolic rate scales to the ¾ power of the animal’s mass.
why is the mechanistic modelling importance of size thanks to the dif laws useful?
shows that the mechanism underling body size abundance is METABOLISM
this is a universal law useful for fish modelling
- trophic levels dif require dif levels of energy
- Mechanistic modelling importance of thermal physiology overview (5)
importance and Boltzmann constant
Caveats
JF Gilooly and AP Allen - defend Boltzmann
Anthony Dell and Samraat Pawar 90%
Mechanistic model thermal physiology
a) why is it important and what can be used to model?
99.9 % of ectotherms depend on temp
Universal law is the Boltzmann constant
from Arrhenius equation
why?
constant and as increase temp this incrases rate of recations in a universal way –> ie luciferase for bioillimuniscence
Enzme kinetics
- best described using michaelis menten equations (derived from Arrhenius) with a few assumptions about chemical enviro of biological systems
Physiology modelling
b)caveats?
may not include
1) oxygen limitation
2) complexity of metabolic network
3) hormoneal regulation
