Rabbit-Evolution

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bosmat bar (Author)

WHAT IS IT?

This model explores the reproduction of rabbits.

HOW IT WORKS

There are two breeds of rabbits: male and female. Rabbits grow older and mature. Girl rabbits go through oestrum every period of time (turn yellow at this point), at which time, if there is a boy rabbit in their vicinity they reproduce. Rabbits' death depends on the age of the rabbit. in our model the rabbit die as he get to 31 year old. The user can choose the initial number of girl-rabbits and boy-rabbits.

HOW TO USE IT

Adjust the slider values (see below), or use the default settings.
Press the SETUP button.
Press the GO button to begin the simulation. The GO button is also used to stop the simulation.
View the COUNT GIRLRABBITS and COUNT BOYRABBITS monitors to view the size of the population for each breed.

Parameters: INITIAL-NUMBER-GIRLRABBITS: The initial size of female rabbits' population INITIAL-NUMBER-BOYRABBITS: The initial size of male rabbits' population

Notes: Female rabbits reproduce 1-3 baby-rabbits randomly.

THINGS TO NOTICE

Observe how the population evolves, where are rabbits born? How do you know that they grow older and die? Watch how the girl rabbits go through oestrum - turn yellow, and how often they give birth. How does the initial number of rabbits, especially girl rabbits effect the rabbits� population?

THINGS TO TRY

Try setting different ratios for the number of male and female rabbits. Try 10 girl rabbits with one male. What happens when the opposite ratio is used? Is there an irreversible point, from which the population cannot rebuild itself?

EXTENDING THE MODEL

This model code can be changed to test a variety of effects: The radius in which a girl rabbit "meets" a boy rabbit and reproduce can be increased or decreased. The probability of death can be changed to one or all the three rabbit ages. Add food to the ecosystem which is consumed and replenished. Add a sterilizing option for female and male rabbits. Make the life of a female rabbit that reproduces shorter, as birth and nursing takes a toll. And many more..

NETLOGO FEATURES

There are two breeds to model two genders: female and male. Some of the features are only for the female (e.g. oestrum, reproduction).

Comments and Questions

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Click to Run Model

; reproduction of rabbits
; create 2 breeds-- girl rabbit and boy rabbit

breed [ boyrabbits a-boyrabbit ]
breed [ girlrabbits a-girlrabbit ]

globals [ clock
          boolean
          max-rabbits
        ]

turtles-own [ age ]                       ;rabbit has attribute of age

to setup                                  ;clear all and set rabbits randomaly by user choise
  clear-all
  ask patches [ set pcolor green ]
  ifelse netlogo-web? [ set max-rabbits 1500 ] [ set max-rabbits 1500 ] ;limit the max rabbits of the model
  create-boyrabbits מספר-ארנבים-התחלתי     ;create the male rabbits, then sets their intial variables
  [
    set color blue set shape "rabbit" set age 1 + random 5 fd random 35 rt random-float 360 set size ( age-size )
  ]
  create-girlrabbits מספר-ארנבות-התחלתי    ;create the female rabbits, then sets their intial variables
  [
    set color pink set shape "rabbit" set age 1 + random 5 fd random 35 rt random-float 360 set size ( age-size )
  ]
  set clock 0
  reset-ticks
end 

to go
 every 0.2                                 ;slow down the model
 [
 ask turtles
     [
        move                               ;wander around and look for a pet or rabbit (of the opposite gender)
        wiggle
        grow-older
        pass-away
     ]
     if count turtles = 0                 ;if we don't have any turtles left, we stop the model
        [ stop ]
     reproduce
     oestrum
     set clock clock + 1
 ]
 if count turtles > max-rabbits [ user-message "הארנבים השתלטו על העולם!" stop ]
end 

to-report age-size                        ;if the age is 10 or older, the size will stay 3
  ifelse (age < 10) [ report 1 + age * 0.2 ] [ report 3 ]
end 

to grow-older                              ;rabbits grow up
  set age age + 1                          ;rabbit''s size will grow as the rabbits grow older
  set size ( age-size )
end 

to wiggle                                  ;they move left and right, here and about
  left random 30
  right random 30
end 

to move
  forward random 2
end 

to oestrum                                   ;every female rabbit has a cycle of oestrum, visualized with the color yellow
  ask girlrabbits
  [ ifelse  ((age = 14) or (age = 17) or (age = 20) )
  [set color yellow][set color pink]]
end 

to reproduce                                 ;every female rabbit can reproduce if she meets few conditions: mature, in oestrum and in the "neiboughrood" of a male rabbit
  ask girlrabbits with [ age > 5 and  color = yellow and (any? boyrabbits in-radius 17 ) ]
    [ hatch (1 + random 2)                   ;she hatches between 1 to 3 baby-rabbits
      [
          set age 0
          set shape "rabbit"
          set size age-size
          ifelse random 2 = 0                ;chance of 1/3 for a boy. 2/3 for a girl
             [ set breed boyrabbits
               set color blue
               set shape "rabbit"
             ]
             [ set breed girlrabbits
               set color pink
               set shape "rabbit"
             ]
         lt random 180                        ;the baby-rabbits wander away, as the way of growing up offsprings
         fd random 5
       ]
     ]
end 

to pass-away
  if (age > 21 ) [ die ] ;a rabbit pass away after age of 31. we set the n-dead in case we want to show it
end

There is only one version of this model, created almost 5 years ago by bosmat bar.

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