Starfish_Planet_3

turtles-own [

  age                     ;; an age counter for each agent/turtle/starfish

  mutator                 ;; a gene that when activated has got three alleles; the neutral one,
                          ;; the positive one (that increase the probability of mutations) and the
                          ;; the negative one (that decrease the probability of mutations)

  tolerance_variation     ;; starfishes can survive in a range of standard energy supply
                          ;; but when the switch tolerance-shift is activated, every starfish can
                          ;; diverge from the standard, as well: the magnitude of the drift is given by
                          ;; the tolerance_variation "gene"
  ]



globals [

  incoming_cosmic_energy  ;; energy coming from external space
  surface_energy          ;; energy measured on the surface of the planet
  n.red                   ;; counter of the red starfishes
  n.white                 ;; counter of the white starfishes
  rw_difference           ;; difference between red and white starfishes
  mmut                    ;; average of mutator genes activity in total population
  mvar                    ;; average of tolerance-shift variation genes in total population
  crowd?                  ;; does the number of starfishes exceed the maximum sustained by the environment?
  ]





;;  ----------   SETUP PROCEDURES   -----------------------------------------------------------------------
;;  -------------------------------------------------------------------------------------------------------

to setup

  clear-all
  reset-ticks

  set incoming_cosmic_energy 0
  set surface_energy 0

  ask patches [set pcolor cyan]        ;; the planet has a cyan background

  crt 500
    [setxy random-xcor random-ycor     ;; the planet is populated by two kinds of starfishes,
    set color red                      ;; the red ones ...
    set shape "star"
    set size 0.7
    set age random 5
    set mutator 0
    set tolerance_variation 0
    ]

  crt 500
    [setxy random-xcor random-ycor
    set color white                    ;; and the white ones
    set shape "star"
    set size 0.7
    set age random 5
    set mutator 0
    set tolerance_variation 0
    ]

  set n.red count turtles with [color = red]
  set n.white count turtles with [color = white]
  set rw_difference n.red - n.white

  set mmut 0
  set mvar 0
  set crowd? false
end 





;;  -------------- RUNTIME PROCEDURES ---------------------------------------------------------------------
;;  -------------------------------------------------------------------------------------------------------

to go

  tick

  ;; the physics of starfish planet is given by an oscillating flux of "cosmic energy"
  set incoming_cosmic_energy (cos(ticks * 31) * energy_oscillation_amplitude) + energy_average

  ;; at the surface of the planet the energetic balance is influenced by the incoming energy,
  ;; and biological factors given by the positive or negative "albedo effect"
  ;; of two different populations of starfishes
  set surface_energy
    (surface_energy + incoming_cosmic_energy) / 2 + rw_difference * albedo_parameter

  ;; the two kinds of alien starfishes populations living on the planet follow a little bit different
  ;; challenge according to their color
  ask turtles [
    if  (color = white) [white-challenge]

    if  (color = red) [red-challenge]
    ]

  ;; if the planet is overcrowded the starfishes arrive to the reproductive age later
  ;; the reproductive process is linked to the mutation chance given by the mutation_rate
  ;; after a mutation a red newborn starfish became white
  ifelse crowd? = false
    [ask turtles [if age > 2 [reproduction]]]
    [ask turtles [if age > 3 [reproduction]]]

  ;; starfishes have all the same life cycle, lasting four cosmic ticks
  ask turtles [
    set age age + 1
    if age > 4 [die]
    ]

  ;; the number of starfishes composing the two subpopulations is counted
  set n.red count turtles with [color = red]
  set n.white count turtles with [color = white]
  set rw_difference n.red - n.white

  ;; the simulation is terminated if both subpopulations are extinguished
  if (n.red + n.white = 0) [stop]

  ;; if the number of total starfishes is excessive, the system senses its state as overcrowded
  ifelse (n.white + n.red) > 1000 [set crowd? true] [set crowd? false]

  set mmut mean [mutator] of turtles
  set mvar mean [tolerance_variation] of turtles
end 

to white-challenge
  ;; the white starfishes have got a survival range included between -17 and 19 unit of cosmic energy
  if (surface_energy >= 19 + tolerance_variation) [die]
  if (surface_energy <= -17 + tolerance_variation) [die]
end 

to red-challenge
  ;; the red starfishes have got a survival range included between -19 and 17 unit of cosmic energy
  if (surface_energy >= 17 - tolerance_variation) [die]
  if (surface_energy <= -19 - tolerance_variation) [die]
end 

to reproduction
  hatch 1 [
    set age 0
    rt random-float 360
    fd 2
    if mutator-gene [if random 100 < environmental_mutation_rate + mutator
      [set mutator mutator + (random 3 - 1)]]
    set size 0.7 + tolerance_variation / 5
    if color = red [red-mutation]
    if color = white [white-mutation]
  ]
end 

to white-mutation
  ;; when tolerance-shift is ON the range of tolerance become a genetic character of starfishes
  ;; so it can change in dependence of mutation rate and it is preferentially increased
  if tolerance-shift [
    if (random 100 < environmental_mutation_rate + mutator) [
      set tolerance_variation (tolerance_variation + random 10 - 0.1)
      if tolerance_variation <= -3 [die]
      ]
    ]
  ;; even if tolerance-shift is OFF the color of newborn starfish can mutate becoming red
    if random 100 < environmental_mutation_rate + mutator [
    set color red
    ]
end 

to red-mutation
  ;; when tolerance-shift is ON the range of tolerance become a genetic character of starfishes
  ;; so it can change in dependence of mutation rate it is preferentially increased
  if tolerance-shift [
    if random 100 < environmental_mutation_rate + mutator [
      set tolerance_variation (tolerance_variation + random 10 - 0.1)
      if tolerance_variation <= -3 [die]
      ]
    ]
  ;; even if tolerance-shift is OFF the color of newborn starfish can mutate becoming white
  ;; as consequence of this the tolerance-variation is inverted, as well
  if (random 100 < environmental_mutation_rate + mutator) [
     set color white
    ]
end