sex-ratio-equilibrium

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My_photo_2 Sugat Dabholkar (Author)

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evolution 

Tagged by Sugat Dabholkar almost 3 years ago

Model group MAM-2016 | Visible to everyone | Changeable by everyone
Model was written in NetLogo 6.0-M5 • Viewed 324 times • Downloaded 20 times • Run 0 times
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globals [
  sex-ratio-list  ;; global-variable to track time-series data (for behavior space experiment)
  ]
breed [males male]
breed [females female]

females-own [
  partner                ;; a variable to temporary store a mating-partner
  carrying?              ;; a boolean to track if a female is carrying a child after mating
  male-child-chance      ;; this is a trait veriable that influences the probability of giving birth to a male child
  temp-male-child-chance ;; a variable to store male-chind-chance for a particular father-mother pair
  gestation              ;; a veriable to track time of carrying a child till a female reachers gesatation-period
  age                    ;; a veriable to keep track of age
]

males-own [
  partner               ;; a variable to temporary store a mating-partner
  male-child-chance     ;; this is a trait veriable that influences the probability of giving birth to a male child
  age                   ;; a veriable to keep track of age
]

;;set-up pupulation of males and females

to setup
  ca
  create-males round ( ( 1 - ini-sex-ratio ) * ini-number ) [
    setxy random-xcor random-ycor
    set shape "male"
    set color green
    set male-child-chance random-normal ini-average-male-child-chance 0.1    ;; males are assinged initial male-child-chance from a random-normal distribution
    set age 0
    set partner nobody
  ]
  create-females round ( ini-sex-ratio * ini-number ) [
    setxy random-xcor random-ycor
    set color blue
    set shape "female"
    set carrying? false
    set partner nobody
    set male-child-chance random-normal ini-average-male-child-chance 0.1  ;; females are assinged initial male-child-chance from a random-normal distribution
  ]
  set sex-ratio-list []
  reset-ticks
end 

to go
  if not any? turtles [stop]
  ask males [
    check-if-dead
    move
    search-a-partner
  ]
  ask females [
    check-if-dead
    if not carrying? [move]
    reproduce
  ]
  update-sex-ratio-list
  tick
end 

to move
    rt random 60
    lt random 60
    fd 1
end 

to search-a-partner  ;; a male procedure
  if count females in-radius 1 with [not carrying?] = 1 and count other males in-radius 1 = 0  [  ;; spatial restriction is used to incorporate density-dependant growth rate
    set partner one-of females in-radius 1 with [not carrying?]                                   ;; this is a common emperically validated assumpotion in many evolution models
    ]
    if partner = nobody [stop]
    ifelse [partner] of partner != nobody [
      set partner nobody
      stop                        ;; just in case two males find the same partner
    ]
    [
      ifelse random-float 1 < mating-chance [
        ask partner [
          set partner myself
          set carrying? true
          set color orange    ;; color oragne indicates carrying female
          set temp-male-child-chance ( male-child-chance + [male-child-chance] of myself ) / 2  ;; sex of a child is determined by male-child-chance (determined by father and mother)
        ]                                                                                       ;; this is a part of the fundamental assumption in Fisher's model
        set partner nobody                                                                      ;; autosomal inheritance of sex-determination-mechanism
      ]
      [
        set partner nobody
      ]
    ]
end 

to reproduce     ;; a female procedure
    if carrying? [
      ifelse gestation = gestation-period [   ;; genstation-period can be set. When it's over, a female gives birth to a a child, starts afrest and can have a new partner
        set gestation 0
        set carrying? false
        set color blue
        set partner nobody
        repeat random max-litter-size + 1 [
          ifelse random-float 1 < temp-male-child-chance [
            hatch 1 [
              set breed males
              set shape "male"
              set color green
              set male-child-chance random-normal [temp-male-child-chance] of myself 0.1  ;; inheritance of male-child-chance is also determined by father and mother.
              set age 0
            ]
          ][
          hatch 1 [
            set male-child-chance random-normal temp-male-child-chance 0.1
            set age 0
          ]
          ]
        ]
      ][
      set gestation gestation + 1
      ]
    ]
end 

to check-if-dead
    ifelse random-float longevity < age [       ;; With age probability of dying increases
      die
    ][
    set age age + 1
    ]
end 

;; reporting procedures for plotting and for behaviorspace experiments

to-report female-percentage
  ifelse any? turtles [
    report ( count females / count turtles ) * 100
  ]
  [
    report 0
  ]
end 

to-report average-male-child-chance
  ifelse any? turtles [
    report mean [male-child-chance] of turtles
  ]
  [
    report 0
  ]
end 

to update-sex-ratio-list
  if ticks > 10000 [
    set sex-ratio-list lput female-percentage sex-ratio-list
  ]
end 

to-report average-sex-ratio
    ifelse length sex-ratio-list > 0 [
    report precision mean sex-ratio-list 2]
    [report 0]
end 

to-report sd-sex-ratio
    ifelse length sex-ratio-list > 0 [
    report precision standard-deviation sex-ratio-list 2]
    [report 0]
end 

There are 2 versions of this model.

Uploaded by When Description Download
Sugat Dabholkar almost 3 years ago Revised final version of the model Download this version
Sugat Dabholkar about 3 years ago Initial upload Download this version

Attached files

File Type Description Last updated
SugatDabholkar-Firehose-Presentation.pdf pdf Firehose Presentation for the MAM-16 class almost 3 years ago, by Sugat Dabholkar Download

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