a multipatch metapopulation model with “human” agents injected
Post on 03-Jan-2016
40 Views
Preview:
DESCRIPTION
TRANSCRIPT
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 1
A Multipatch Metapopulation Model with “Human” Agents Injected
Bruce EdmondsCentre for Policy Modelling
Manchester Metropolitan University
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 2
Motivation
Social Model
Ecological Model
Complex Individual-based Model
SimpleSystem-dynamics
Model
Complex Individual-based Model
SimpleSystem-dynamics
Model
Combined Complex Model
Socio-Ecological Model
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 3
Model of Ecology
• A wrapped 2D grid of well-mixed patches with:– energy (transient)– bit string of characteristics
• Organisms represented individually with its own characteristics, including:– bit string of characteristics– energy– position– stats recorders
A well-mixed patch
Each individual
represented separately
Slow random rate of migration
between patches
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 4
How Dominance is Decided
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 5
Model sequence each simulation tick
1. Input energy equally divided between patches.
2. Death. A life tax is subtracted, some die, age incremented
3. Initial seeding. until a viable is established, random new individual
4. Energy extraction from patch. energy divided among the individuals there with positive score when its bit-string is evaluated against patch
5. Predation. each individual is randomly paired with a number of others on the patch, if dominate them, get a % of their energy, other removed
6. Maximum Store. energy above a maximum level is discarded.
7. Birth. Those with energy > “reproduce-level” gives birth to a new entity with the same bit-string as itself, with a probability of mutation, Child has an energy of 1, taken from the parent.
8. Migration. randomly individuals move to one of 4 neighbours
9. Statistics. Various statistics are calculated.
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 6
Key advantages of this
• Produces a complex space of changing food webs• Model creates endogenous shocks and unpredictable
adaptions (to, for example, man)• Species arms-races, predator-prey dynamics, waves of
species spread etc. all exhibited• Levels of environmental variety, size, granularity etc.
are determined by paramters• Mutation and migration happen in parallel• “Equilibrium” almost never observed• Diversity of ecologies are emergent outcomes• “Human” agents can be embedded in food chains and
the combined complexity of this explored
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 7
Non-Viable Ecology
Typical Non-Viable Ecology the world state (left) Number of Species (centre) Log, 1 + Number of Individuals at
each trophic level (right)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 8
Dominant Species Ecology
Typical Dominant Species Ecology the world state (left) Number of Species (centre) Log, 1 + Number of
Individuals at each trophic level (right)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 9
Rich Plant Ecology
Typical Rich Plant Ecology the world state (left) Number of Species (centre) Log, 1 + Number of Individuals at each
trophic level (right)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 10
Mixed Ecology
Typical Mixed Ecology the world state (left) Number of Species (centre) Log, 1 + Number of Individuals at each
trophic level (right)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 11
Longer-Term Trends in Num. Species
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 12
Neutral patches, random migration, plants only
• As predicted by Hubble’s “Neutral Theory”
• “skewed s-shaped” relative species abundance curve
• “Multinomial distribution” of log2 species distribution
• Except, maybe, species-area scatter chart
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 13
Neutral Patches, local migration, plants only
• unchanged “skewed s-shaped” relative species abundance curve
• “Multinomial distribution” of log2 species distribution but with more lower abundance species
• Pretty flat species-area scatter plot
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 14
Selective patches, random migration, plants only
• “Linear” drop in log 2 species abundance
• “Exponential” shaped relative species abundance graph
• Flatter species area scatter plot
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 15
Neutral Patches, random migration, predators
• Lots of new species plus flatter log 2 species distribution
• flat or curved species abundance distribution
• a variety of species-area curves
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 16
Other combinations
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 17
Adding “Human” Agents
• The agents representing humans are “injected” (as a group) into the simulation once an ecology of other species has had time to evolve
• The state of the ecology is then evaluated some time later or over a period of time
• These agents are the same as other individual in most respects, including predation but “humans”:– can change their bit-string of skills by imitating others on the
same patch (who are doing better than them)– might have a higher “innovation” rate than mutation– might share excess food with others around– might have different migration rates etc.
• Could have many other learning, reasoning abilities
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 18
Extinction due to Consuming all Others
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 19
Waves of (Human) Predator-Prey Patterns
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 20
Example run with: selective environment, local migration, predators, and “humans” @ tick 2000
@tick2000 – before “humans”
@tick5000 – after “humans”
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 21
Some of the dynamics of the example run
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 22
Effect of humans vs. environmental complexity
diversity of ecology, blue=with humans,
red=without
proportion of ecology types, red=plant, blue=mixed, purple=single species,
green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 23
Effect of humans vs. general migration rate
diversity of ecology, blue=with humans,
red=without
proportion of ecology types, red=plant, blue=mixed, purple=single species,
green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 24
Effect of humans vs. food input to world
diversity of ecology, blue=with humans,
red=without
proportion of ecology types, red=plant, blue=mixed, purple=single species,
green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 25
Num. Species vs. Num. Variants (all with humans)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 26
Innovation vs. migration rate (all with humans)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 27
Migration vs. food rate (all with humans)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 28
Human migr. rate vs. diversity (all with humans, other entities having 0.1 migration rate)
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 29
Starting from plant ecology (with humans)
Starting from a Plant Ecology the effects of innovation rate/mutation rate (left) and people migration rate/entity
migration rate (right) , red=plant, blue=mixed, purple=single species, green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 30
Starting from mixed ecology (with humans)
Starting from a Mixed Ecology the effects of innovation rate/mutation rate (left) and people migration rate/entity
migration rate (right) , red=plant, blue=mixed, purple=single species, green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 31
Starting from single species ecology (with humans)
Starting from a Single Species Ecology the effects of innovation rate/mutation rate (left) and people migration rate/entity migration rate (right) , red=plant, blue=mixed,
purple=single species, green=non-viable
A Multipatch Metapopulation Model with “Human” Agents Injected. Manchester Complexity Seminar, 18th Oct 2013. slide 32
The End!
Bruce Edmonds:http://bruce.edmonds.name
Centre for Policy Modelling:http://cfpm.org
A paper describing some of this, the model, these slides at: http://cfpm.org/cpmrep222.html
top related