!!!---cooperation2.nlogo

NETLOGO

turtles-own [energy  c-type]
patches-own [ grass temp ]
globals [num-coop num-greed]
;breeds [ coop greed]

to setup
	ca

	ask patches [
		set grass max-grass
		color-grass
	]

	crt number-coop + number-g

	ask turtles [
		set c-type random 2 ;; set the breed
		;create-coop number-coop
		;create-greed number-g


		ifelse (c-type = 0 )
			[setc pink]
			[setc blue]

		setxy random 2000 random 2000
		set energy metabolism * 4
	]

    set-plot-pen "coop"
	set-plot-pen-color pink

	set-plot-pen "greed"
	set-plot-pen-color blue

	set-plot-x-range 0 1
	set-plot-y-range 0 1

	auto-plot-on
end

to go
	ask turtles [
		ifelse c-type = 0
		[
			move
			eat-coop
			reproduce
		]
		[
			move
			eat-greed
			reproduce
		]
	]
	ask patches [
		grow-grass
		color-grass
	]

    set num-coop 0
    set num-greed 0
    ask turtles [ ifelse c-type = 0 [ set num-coop num-coop + 1][set 
num-greed num-greed + 1] ]

    set-plot-pen "coop"
	plot num-coop

	set-plot-pen "greed"
	plot num-greed
end

to reproduce
	if(energy > rep-level)[
		set energy energy - rep-cost
		hatch[]
		ifelse (c-type = 0)
		[
		   ;if ((random 100) < 1)
				;	 [setbreed greed]
   		 ;if (breed = greed)
	  	;[ask greed [setc blue]]
      	;ask coop [setc pink]
			setc pink
		]
		[
		   ;if ((random 100) < 8)
			;	 [setbreed coop]
			 ;  if (breed = coop)
	 	 	;[ask coop [setc pink]]
			;ask greed [setc blue]
			setc blue
		]
	]
end

to grow-grass
		set temp l-h-thresh
		ifelse ( grass >= temp)[
			if(h-g-chance >= (random 100))[
					set grass grass + 1
			]
		][
			if(l-g-chance >= (random 100))[
					set grass grass + 1
			]
		]

		if(grass > max-grass ) [set grass max-grass]
end

to color-grass
	scale-pc green grass 0 (2 * max-grass)
end

to move
	fd 1 / viscosity
	seth random 360
	set energy energy - metabolism
	if (energy < 0) [die]
end

to eat-coop
	if(grass > l-h-thresh )[
		set grass grass - 1
		set energy energy + grass-energy
	]
end

to eat-greed
	if(grass > 0)[
		set grass grass - 1
		set energy energy + grass-energy
	]
end



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CC-WINDOW
10
262
307
437
Default

BUTTON
67
10
119
37
go
go
T
1
T
OBSERVER

BUTTON
9
9
58
37
setup
setup
NIL
1
T
OBSERVER

SLIDER
140
60
257
97
number-coop
number-coop
0.0
100.0
6.0
1.0
1

SLIDER
7
60
116
93
number-g
number-g
0.0
100.0
6.0
1.0
1

SLIDER
139
210
270
242
l-h-thresh
l-h-thresh
0.0
99.0
5.0
1.0
1

SLIDER
139
138
270
167
h-g-chance
h-g-chance
0.0
99.0
75.0
1.0
1

SLIDER
142
18
254
52
viscosity
viscosity
1.0
20.0
12.0
1.0
1

SLIDER
139
174
270
204
max-grass
max-grass
0.0
40.0
10.0
1.0
1

SLIDER
4
209
127
241
rep-level
rep-level
0.0
200.0
101.0
1.0
1

SLIDER
5
139
129
168
grass-energy
grass-energy
0.0
200.0
51.0
1.0
1

SLIDER
6
102
130
134
metabolism
metabolism
0.0
99.0
10.0
1.0
1

SLIDER
139
101
270
133
l-g-chance
l-g-chance
0.0
99.0
30.0
1.0
1

PLOT
495
31
744
230
plot1
xAxis
yAxis

SLIDER
6
174
129
202
rep-cost
rep-cost
0.0
99.0
40.0
1.0
1

GRAPHICS-WINDOW
284
27
488
231
12
12
8.16
1

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WHAT IS IT?
-----------
This is an evolutionary biology model.  In it, different breeds of cows 
compete for natural resources. Individuals that are more successful in 
getting the resources will reproduces more often, and will thus be more 
evolutionarily successful.
There are two breeds of agents: greedy and cooperative cows. Every turn, 
each cow looks at the patch that it is currently on, and eats a unit of 
grass.  The greedy cows eat the grass regardless of the length of the grass 
on the current patch.  The cooperative cows won't eat the grass below a 
certain height.  This behavior is significant because below a certain height 
(called the 'growth threshold') the grass grows at a far slower rate than 
above it.  Thus, the cooperative agents leave more food for the overall 
population at a cost to their individual well-being, while the greedy agents 
eat the grass down to the nub, regardless of the effect on the overall 
population.

HOW TO USE IT?
--------------
GO: Starts and stops the model.

SETUP: Resets the simulation according to the parameters set
by the sliders.

NUMBER-G: Sets the number of greedy cows.

NUMBER-COOP: Sets the number of cooperative cows.

VISCOSITY: This value determines the limitations on the movement of the 
cows.  At a value of 0 or 1, each cow moves forward 1 each turn.  As the 
value is increased, the cows are limited to a fraction of their movement.  
This value is the denominator of that fraction; thus, the higher the 
viscosity, the less the mobility of the cows.  The term 'viscosity' derives 
from imagining a thick or viscous fluid as the medium through which the 
agents must move.

GRASS-ENERGY: Each time a cow can each some grass from the patch that it 
currently occupies, it increases its energy by the value of this slider.

METABOLISM: Every turn, each cow loses the amount of energy set by this 
slider.  If the cows energy reaches 0, it dies.  Every cow starts with a 
default energy of 50, which means it can go five turns without eating.

REP-LEVEL: If a cow's energy reaches the value of this slider, it 
reproduces.  This value represents the food-gathering success that a cow 
would have to have in order to be able to reproduce.

REP-COST: Each time a cow reproduces, it loses the amount of energy set by 
this slider.  This value represents the energy cost of reproduction.

L-G-CHANCE: This value is the percentage chance that the grass below the 
growth threshold will grow back.  The higher this value, the less the 
descrepancy between the behaviors of the cooperative and greedy cows.

H-G-CHANCE: This value is the percentage chance that the grass above the 
growth threshold will grow back.  The lower this value, the less the 
descrepancy between the behaviors of the cooperative and greedy cows.

MAX-GRASS:  This value sets the highest length to which the grass can grow.

L-H-THRESH:  This value sets the growth threshold.  At, or above this value, 
the grass grows back with H-G-CHANCE.  Beclow this value, the grass grows 
back with L-G-CHANCE.


THINGS TO NOTICE
----------------
Using the default settings, notice how the greedy (blue) cows quickly take 
over the world.  Look at the number of cooperative versus greedy agents. 
Also, look at the different growth habits on the graph.  Which population 
expanded first?


THINGS TO TRY
-------------
Slowly increase the VISCOSITY slider.  What happens to the graph?  What 
happens to the populations?

At what value of VISCOSITY do the populations' growth rates change 
dramatically?  What does this indicate about the evolutionary advantages of 
Cooperating versus being Greedy?  What are the important environmental 
factors?

Change the METABOLISM and the GRASS-ENGERY values.  How do these values 
affect the model?

Change the L-G-CHANCE and the H-G-CHANCE values.  How do these values affect 
the model?

How does the L-H-THRESH value affect the growth of the populations?


EXTENDING THE MODEL
-------------------
This model explores only one type of cooperative behavior, namely eating the 
grass above the growth threshold (the L-H-THRESH value).  What other 
cooperative, or altruistic, behaviors could be modeled that hurt individual 
fitness, while helping the group overall?  What other environmental 
conditions than grass length could be used to effect the health of a 
population?

This model relies primarily upon population viscosity (the VISCOSITY slider) 
to alter the behavior of the cows to allow for the success of the 
cooperative agents.  What other variables could have such a drastic effect 
on the evolutionary success of populations?

Also, consider that in this model the behaviors are fixed.  What would 
happen if the agents learned, or changed their behavior based on food 
availability?

RELATED MODELS
--------------
Altruism (Trait) Model



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NetLogo 1.0 Beta 5
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