Divergent Evolution

;; Simulate divergent evolution in a population. Have 2 different regions of the world, 
;; representing 2 different food sources for the turtles. Turtles with bigger beaks are
;; more suited to eat one region, smaller are more suited to the other.
;; All turtles start out with a similar sized "beak."


turtles-own [ beak-size energy ]
patches-own [ countdown food-type ]

to setup
  ca
  ask patches 
  [ set countdown random food-regrowth-time
    ifelse random 100 < percent-green 
    [set pcolor 56] [set pcolor 46]
    ifelse pcolor = 46 
    [ set food-type 1 ]
    [ set food-type 2 ] ]
  crt initial-birds 
  [ setxy random-xcor random-ycor
    set shape "bird side"
    set size 2
    set beak-size (10 + random-float 1 - random-float 1)
    set color scale-color violet beak-size 0 20
    set energy initial-energy ]
  reset-ticks
end 

to go
  move
  eat-food
  reproduce
  death
  grow-food
  tick
end 

to move
  ask turtles 
  [ rt random 50
    lt random 50 
    let dist random-float 1
    fd dist
    set energy energy - dist ]
end 

to eat-food
  ask turtles
  [ if beak-size > 0 and beak-size < 20
    [ if pcolor = 46 
      [ if max-one-of turtles-here [beak-size] = self 
        [ set energy energy + energy-from-food
          set pcolor 36 ]]
      if pcolor = 56 
      [ if min-one-of turtles-here [beak-size] = self 
        [ set energy energy + energy-from-food
          set pcolor 36 ]]]]
end 

to reproduce
  ask turtles 
  [ if energy > reproduction-energy
    [ set energy energy - initial-energy
      hatch 1 
      [ set energy initial-energy
        set beak-size beak-size + random-float 0.5 - random-float 0.5 
        set color scale-color violet beak-size 0 20 ]]]
end 

to death
  ask turtles 
  [ if energy <= 0 [ die ]]
end 

to grow-food
  ask patches 
  [ if pcolor = 36 
    [ ifelse countdown <= 0
      [ ifelse food-type = 1 
        [ set pcolor 46 ]
        [ set pcolor 56 ]
        set countdown food-regrowth-time ]
      [ set countdown countdown - 1 ]]]
end