Bluebles2

No preview image

1 collaborator

Kay Ramey (Author)

WHAT IS IT?

Bluebles2 is a model of natural selection due to changes in the environment and consequent changes in food supply. In this model, there are four types of Bluebles: Spiny Bluebles, Blue Longneck Bluebles, Green Longneck Bluebles and Green Bluebles. This model shows what happens to the Bluebles when they are forced to migrate to a new habitat. While their old habitat was a prairie with lots of grass for them to eat, this new habitat is a forest, where the only food they can eat is the leaves growing high up in the trees.

HOW IT WORKS

The model starts with a random arrangement of the four different types of Bluebles, the amounts of which are determined by the initial-number-x sliders (eg. "initial-number-spinybluebles", "initial-number-bluelongneckbluebles," etc.). The Bluebles use energy to move around, which they must regain by eating. Bluebles eat trees (the green patches) to regain energy. After it has been eaten, the trees regrow after a random number of ticks (0-10). If a Blueble's energy drops below zero, it dies.

The Bluebles also reproduce. The likelihood or proability (%) of their reproduction will be based on the "Bluebles-reproduce" slider. Each Blueble will hatch a Blueble of the same type when it reproduces. In other words, Spiny Bluebles will hatch more Spiny Bluebles, Green Bluebles will hatch more Green Bluebles, Blue Longneck Bluebles will hatch more Blue Longneck Bluebles and Green Longneck Bluebles will hatch more Green Longneck Bluebles.

HOW TO USE IT

Adjust the initial-number-spinybluebles, initial-number-greenbluebles, initial-number-bluelongneckbluebles and initial-number-greenlongneckbluebles sliders to determine how many of each breed the model will start with. Then adjust the "Bluebles-reproduce" sliders to set the likelihood of reproduction for Bluebles.

Note that the "Bluebles-reproduce_ slider adjusts the likelihood of reproduction for all four types of Bluebles.

After adjusting the sliders, press the "Setup" button to populate the model and then the "Go" button to run it. To stop the model, simply press the "Go" button a second time.

THINGS TO NOTICE

Notice that if you set the model so that there are 50 Spiny Bluebles, 50 Blue Longneck Bluebles, 50 Green Longneck Bluebles and 50 Green Bluebles and so that Bluebles have a 2% chance of reproducing, the model shows trait extinction of the shortneck Blueble body types. It is also important to note that this happens very quickly. Why do you think this is?

THINGS TO TRY

First, try adjusting the settings so that there are 50 Spiny Bluebles, 50 Blue Longneck Bluebles, 50 Green Longneck Bluebles and 50 Green Bluebles and so that Bluebles have a 2% chance of reproducing.

After you have run the model once with the settings above, try adjusting the Blueble settings to see if you can get different results.

Now try adjusting the settings to see if you can create a stable ecosystem consisting of Bluebles and Trees. Can you find any settings that generate a stable ecosystem?

EXTENDING THE MODEL

One way to extend the model would be to try changing the reproduction rules. For example, what would happen if reproduction depended on energy rather than being determined by a fixed probability? What would happen if Longneck Bluebles didn't produce only Longneck Bluebles, but were able to produce Spiny or Green Bluebles as well?

Another way to extend the model would be to build both trees and grass into the patches, with sliders for the proportion of patches dedicated to eat. With the Longneck Bluebles eating the trees and the other Bluebles eating the grass, what might happen to the population of Bluebles under different vegetation settings?

NETLOGO FEATURES

Note the use of breeds to model four different kinds of "turtles": Spiny Bluebles, Blue Longneck Bluebles, Green Longneck Bluebles and Green Bluebles.

Note the use of patches to model trees.

Note the use of the "Turtle Shapes Editor" tool to create unique and relatively complex turtle shapes.

RELATED MODELS

Look at "Wolf-Sheep Predation" for another example of patches as food sources for turtles.

Comments and Questions

Please start the discussion about this model! (You'll first need to log in.)

Click to Run Model

globals [trees]  ;; keep track of how many trees there are
          
;; spiny bluebles, blue longneck bluebles, green longneck bluebles and green bluebles are all breeds of turtles
breed [spinybluebles spinyblueble]
breed [bluelongneckbluebles bluelongneckblueble]
breed [greenlongneckbluebles greenlongneckblueble]
breed [greenbluebles greenblueble] 
turtles-own [energy]       
patches-own [countdown]

to setup
  clear-all
  ask patches [ set pcolor 62 ]
  ask patches [
      set countdown random 10 ;; initialize tree grow clocks randomly
      set pcolor one-of [62 white] ;; dark green or white
    ]
 
   set-default-shape spinybluebles "spiny blueble"
  create-spinybluebles initial-number-spinybluebles  ;; create the spiny bluebles, then initialize their variables
  [
    set color 105 ;; blue
    set size 7  ;; easier to see    
    set energy random 50
    setxy random-xcor random-ycor
  ]
   set-default-shape bluelongneckbluebles "longneck blueble"
  create-bluelongneckbluebles initial-number-bluelongneckbluebles  ;; create the blue longneck bluebles, then initialize their variables
  [
    set color 105 ;; blue
    set size 7  ;; easier to see    
    set energy random 50
    setxy random-xcor random-ycor
  ]
  set-default-shape greenlongneckbluebles "longneck blueble"
  create-greenlongneckbluebles initial-number-greenlongneckbluebles  ;; create the green longneck bluebles, then initialize their variables
  [
    set color 64 ;; green
    set size 7  ;; easier to see    
    set energy random 50
    setxy random-xcor random-ycor
  ]
  
   set-default-shape greenbluebles "spiny blueble"
  create-greenbluebles initial-number-greenbluebles  ;; create the green bluebles, then initialize their variables
  [
    set color 64 ;; green
    set size 7  ;; easier to see    
    set energy random 50
    setxy random-xcor random-ycor
  ]
   RESET-TICKS
end 

to go
  if not any? turtles [ stop ]
  ask spinybluebles [
    move
      set energy energy - 1  ;; deduct energy for spinybluebles
    death
    reproduce-spinybluebles
  ]
   ask bluelongneckbluebles [
    move
      set energy energy - 1  ;; deduct energy for bluelongneckbluebles 
      eat-trees
    death
    reproduce-bluelongneckbluebles
  ]
      ask greenlongneckbluebles [
    move
      set energy energy - 1  ;; deduct energy for greenlongneckbluebles
      eat-trees 
    death
    reproduce-greenlongneckbluebles
  ]
  ask greenbluebles [
    move
      set energy energy - 1  ;; deduct energy for greenbluebles 
    death
    reproduce-greenbluebles
  ]
 
 ask patches [ grow-trees ] 
  set trees count patches with [pcolor = 62] ;; dark green
  tick
end 

to move  ;; turtle procedure
  rt random 50
  lt random 50
  fd 1
end 

to eat-trees  ;; longneck bluebles procedure
  ;; longneck bluebles eat grass, turn the patch white
  if pcolor = 62 [ ;; dark green
    set pcolor white 
    set energy energy + 2 ;; longneck bluebles gain energy by eating
  ]
end 

to reproduce-spinybluebles  ;; spinybluebles procedure
  if random-float 100 < bluebles-reproduce [  ;; throw "dice" to see if you will reproduce
    set energy (energy / 2)                ;; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]   ;; hatch an offspring and move it forward 1 step
  ]
end 

to reproduce-bluelongneckbluebles  ;; bluelongneckbluebles procedure
  if random-float 100 < bluebles-reproduce [  ;; throw "dice" to see if you will reproduce
    set energy (energy / 2)                ;; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]   ;; hatch an offspring and move it forward 1 step
  ]
end 

to reproduce-greenlongneckbluebles  ;; bluelongneckbluebles procedure
  if random-float 100 < bluebles-reproduce [  ;; throw "dice" to see if you will reproduce
    set energy (energy / 2)                ;; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]   ;; hatch an offspring and move it forward 1 step
  ]
end 

to reproduce-greenbluebles  ;; greenbluebles procedure
  if random-float 100 < bluebles-reproduce [  ;; throw "dice" to see if you will reproduce
    set energy (energy / 2)                ;; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]   ;; hatch an offspring and move it forward 1 step
  ]
end 

to death  ;; turtle procedure
  ;; when energy dips below zero, die
  if energy < 0 [ die ]
end 

to grow-trees  ;; patch procedure
  ;; countdown on white patches: if reach 0, grow some grass
  if pcolor = white [
    ifelse countdown <= 0
      [ set pcolor 62
        set countdown 10 ]
      [ set countdown countdown - 1 ]
  ]
end

There is only one version of this model, created over 13 years ago by Kay Ramey.

Attached files

No files

This model does not have any ancestors.

This model does not have any descendants.

NetLogo