Breeding Bunnies

Breeding Bunnies preview image

2 collaborators

Light_dependent_reaction_background Luke Elissiry (Author)
Default-person Robin Groch (Teacher)

Tags

biology 

Tagged by Luke Elissiry about 5 years ago

evolution 

Tagged by Luke Elissiry about 5 years ago

genetics 

Tagged by Luke Elissiry about 5 years ago

natural selection 

Tagged by Luke Elissiry about 5 years ago

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Breeding Bunnies

Made by Luke Elissiry with help and ideas from Mr. Johnson, Evan and Dana Laufer, and Mrs. Groch.

WHAT IS IT?

This model examines natural selection in a population of wild rabbits. Evolution, on a genetic level, is a change in the frequency of alleles in a population over a period of time. Breeders of rabbits have long been familiar with a variety of genetic traits that affect the survivability of rabbits in the wild, as well as in breeding populations. One such trait is the trait for furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in the wild because the cold English winters are a definite selective force against it.

Note: In this model, the dominant allele for normal fur is represented by F and the recessive allele for no fur is represented by f. Bunnies that inherit two F alleles or one F and one f allele have fur, while bunnies that inherit two f alleles have no fur.

HOW IT WORKS

The alleles at setup are randomly distributed into bunnies with two alleles each. If a bunny has at least one fur allele, it has fur. Before a new generation, the homozygous recessive bunnies die and their no fur alleles are lost due to the cold. The cycle continues until evolution causes the no fur allele to become rare in the bunny population.

HOW TO USE IT

The Setup button creates the alleles. Every time the Generation button is pressed, the alleles are randomly distributed into bunnies.

THINGS TO NOTICE

The data after each generation below the allele sliders can be used to fill in the [Gene Frequency Graph] (http://www-tc.pbs.org/wgbh/evolution/educators/lessons/lesson4/4bunniesdata.pdf).

Also, notice how the findings differ over time to the right of the model in the plots.

THINGS TO TRY

Change the amount of starting alleles to see how the frequency of the alleles changes.

EXTENDING THE MODEL

  • More controls
  • Bunnies physically breed
  • Save data from prior tests and average it to show probability.

CREDITS AND REFERENCES

For use with Breeding Bunnies activity by PBS: http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act1.html

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Click to Run Model

breed [bunnies]
bunnies-own [fur allele1 allele2]
globals [furallele nofurallele breed?]

to setup
  ca
  reset-ticks
  ask patches [; create background
    set pcolor 9.9 - (random 5)
    ]
  diffuse pcolor 1
  create-bunnies amount-fur-alleles [; creates alleles
    set size 1.5
    set color brown
    set shape "circle"
    setxy random-xcor random-ycor
    set fur true
    ]
  create-bunnies amount-no-fur-alleles [
    set size 1.5
    set color pink
    set shape "circle"
    setxy random-xcor random-ycor
    set fur false
    ]
   set furallele count bunnies with [fur = true]; counts alleles for first generation
   set nofurallele count bunnies with [fur = false]
end 

to generation
  ask bunnies [die]
  set breed? true; starts loop
  while [breed? = true] [
    create-bunnies 1 [
      set size 2
      set shape "rabbit"
      setxy random-xcor random-ycor
      if furallele > 0 and nofurallele > 0 [
        ifelse (random (furallele + nofurallele)) < furallele
          [set allele1 true]
          [set allele1 false]
        ]; sets allele1 random depending on possible alleles left
      if furallele > 0 and nofurallele = 0 [set allele1 true]
      if furallele = 0 and nofurallele > 0 [set allele1 false]
      if allele1 = true [set furallele (furallele - 1)]; removes allele1 from possible alleles left
      if allele1 = false [set nofurallele (nofurallele - 1)]
      if furallele > 0 and nofurallele > 0 [
        ifelse (random (furallele + nofurallele)) < furallele
          [set allele2 true]
          [set allele2 false]
        ]; sets allele2 random depending on possible alleles left
      if furallele > 0 and nofurallele = 0 [set allele2 true]
      if furallele = 0 and nofurallele > 0 [set allele2 false]
      if allele2 = true [set furallele (furallele - 1)]; removes allele2 from possible alleles left
      if allele2 = false [set nofurallele (nofurallele - 1)]
      ifelse allele1 = true or allele2 = true [set color brown][set color pink]; sets color depending on alleles
      ]
    if (furallele + nofurallele) = 0 [set breed? false]; if no more bunnies can be created, stops cycle
    ]
  set furallele (furallele + count bunnies with [allele1 = true and allele2 = true] * 2); sets number of possible alleles for next generation
  set furallele (furallele + count bunnies with [allele1 = true and allele2 = false] + count bunnies with [allele1 = false and allele2 = true])
  set nofurallele (nofurallele + count bunnies with [allele1 = true and allele2 = false] + count bunnies with [allele1 = false and allele2 = true])
  tick 
end 

There are 2 versions of this model.

Uploaded by When Description Download
Luke Elissiry about 5 years ago Bug fix involving probabilities for alleles Download this version
Luke Elissiry about 5 years ago Initial upload Download this version

Attached files

File Type Description Last updated
4_bunnies_data.pdf pdf Gene Frequency Graph - used for PBS activity about 5 years ago, by Luke Elissiry Download
Breeding Bunnies.png preview Preview for 'Breeding Bunnies' about 5 years ago, by Luke Elissiry Download

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