Complex organism evolution

breed [bugs bug]                                  ; efficiency = energy obtained from eating plants
bugs-own [ energy threshold efficiency ]          ; threshold = energy required for reproduction

to setup
  clear-all
  set-default-shape bugs "bug"
  create-bugs 250 [ set color red  set threshold 5 ]     ; simple (efficient) species
  create-bugs 250 [ set color blue  set threshold 20 ]   ; complex species (4*size of simple)
  ask patches [ if random-float 100 < 15 [ set pcolor green ] ]
  ask bugs [ setxy random-xcor random-ycor  set energy random 10  set efficiency 0.4 ]
  reset-ticks
end 

to go
  grow-grass
  if not any? bugs with [color = red] [ stop ]
  if not any? bugs with [color = blue] [ stop ]
  if count bugs > 1000 [ stop ]
  ask bugs  [move   eat-grass   if energy > threshold [reproduce]   death]
  tick
end 

to grow-grass
;  ask patches [ if pcolor = black [ if random-float 1000 < 15 [ set pcolor green ] ] ]
  ask patches [ if pcolor = black and random-float 1000 < 15 [ set pcolor green ] ]
end 

to move                                                           ; moving takes energy
  rt random 50 lt random 50 fd 1    set energy energy - 0.3
end 

to eat-grass                                                      ; bugs gain energy by eating grass
  let penergy 5
  set penergy penergy * efficiency                                ; some bugs get more from plants
  if pcolor = green [ set pcolor black  set energy energy + penergy ]
end 

to reproduce                                                      ; give birth to a new bug
  set energy energy / 2.0                             ; energy expended even if offspring not viable
  let rn random-float 1000
  if color = red [
    if rn <= 1 [                                                  ; produce improved offspring
      hatch 1 [ set efficiency efficiency + 0.05 fd 1 ] ]
    if (rn > 1) and (rn <= 951)                                   ; use cumulative probability
      [ hatch 1 [ fd 1 ] ] ]                                      ; produce clone
  set rn random-float 1000
  if color = blue [
    if rn <= 42 [                                                 ; produce improved offspring
      hatch 1 [ set efficiency efficiency + 0.05 fd 1 ] ]
    if (rn > 42) and (rn <= 952)                                  ; use cumulative probability
      [ hatch 1 [ fd 1 ] ] ]                                      ; produce clone
end 

to death                                                          ; die if all energy consumed
  if energy < 0 [ die ]
end