globals [ dom rec hetero ] breed [hawks hawk] breed [mice mouse] hawks-own [ vision age hawk-geno ] mice-own [ camo mouse-geno ] to setup ca ; So code is easier to read set dom 1 set hetero 2 set rec 3 ask patches [ set pcolor 65 + random-float 3 ] create-hawks init-hawks [ set shape "hawk" set color 36 set age 0 set hawk-geno round random 3 + 1 ; random initial geno freqs set vision random-normal init-mean-vision init-SD-vision if vision < 0 [set vision 0] ; keep scores non-negative ] create-mice init-mice [ set shape "mouse top" set size .3 set color 32 set mouse-geno round random 3 + 1 ; random initial geno freqs set camo random-normal init-mean-camo init-SD-camo if camo < 0 [set camo 0] ; keep scores non-negative ] distribute reset-ticks end to go if ticks = 30 [stop] ask hawks [hunt] ask hawks [starve] ask mice [evolve-mice?] distribute tick end to hunt if any? mice-here [ ; if there are mice on this patch if vision >= min [camo] of mice-here [ ; and they can be seen if-else vision > min [camo] of mice-here [evolve-hawks?] ; if vision > camo eat and reproduce [if random 2 = 0 [evolve-hawks?]] ; else vision = camo so flip a coin ] ] ; recurse to continue eating until all possible meals eaten if any? mice-here and vision >= min [camo] of mice-here [hunt] end to evolve-hawks? ifelse hawks-evolve? [eat-and-evolve] [eat-and-reproduce] end to eat-and-evolve ask min-one-of mice-here [camo] [die] ; eat the mouse ifelse vision-dominant? [hatch 2 ; better vision is dominant [set age ticks ; get random mate set hawk-geno child-geno [hawk-geno] of self [hawk-geno] of one-of other hawks ifelse hawk-geno != rec ; ^^ reproduction ^^ [ set vision vision + random-float 1] ; dom or hetero so improve vision [ set vision vision - random-float 1 ; rec so decrease vision if vision < 0 [set vision 0] ] ] ] [hatch 2 ; better vision is recessive [set age ticks ; get random mate set hawk-geno child-geno [hawk-geno] of self [hawk-geno] of one-of other hawks ifelse hawk-geno != rec ; ^^ reproduction ^^ [ set vision vision - random-float 1 ; dom or hetero so decrease vision if vision < 0 [set vision 0]] [set vision vision + random-float 1] ; rec so increase vision ] ] die ; die end to eat-and-reproduce ask min-one-of mice-here [camo] [die] ; eat the mouse hatch 2 [ ; produce 2 offspring with random vision and genotype set age ticks set hawk-geno child-geno [hawk-geno] of self [hawk-geno] of one-of other hawks set vision round random-normal init-mean-vision init-SD-vision if vision < 0 [set vision 0] ; keep scores non-negative ] die ; die end to starve if (ticks - age >= 2) [die] ; if a hawk hasn't eaten in 2 s it dies end to evolve-mice? ifelse mice-evolve? [reproduce-and-evolve] [reproduce] end to reproduce-and-evolve if not any? other mice-here [ ; if there is no competition ifelse camo-dominant? [ hatch 2 ; better camo is dominant ; get random mate [set mouse-geno child-geno [mouse-geno] of self [mouse-geno] of one-of other mice ifelse mouse-geno != rec ; ^^ reproduction ^^ [set camo camo + random-float 1] ; dom or hetero so improve camo [set camo camo - random-float 1 ; rec so decrease camo if camo < 0 [set camo 0] ] ] ] [ hatch 2 ; better camo is recessive ; get random mate [set mouse-geno child-geno [mouse-geno] of self [mouse-geno] of one-of other mice ifelse mouse-geno != rec ; ^^ reproduction ^^ [set camo camo - random-float 1 ; dom or hetero so decrease camo if camo < 0 [set camo 0]] [set camo camo + random-float 1] ; rec so increase camo ] ] die ; die ] end to reproduce if not any? other mice-here [ ; if there is no competition hatch 2 [ ; produce 2 offspring with random camo and genotpyes set mouse-geno child-geno [mouse-geno] of self [mouse-geno] of one-of other mice set camo round random-normal init-mean-camo init-SD-camo if camo < 0 [set camo 0] ; keep scores non-negative ] die ; die ] end to distribute ask mice [setxy random-xcor random-ycor set heading random 359] ask hawks [setxy random-xcor random-ycor set heading random 359] end to reset set mice-evolve? true set camo-dominant? true set init-mice 50 set init-mean-camo 5 set init-SD-camo 1.2 set hawks-evolve? true set vision-dominant? true set init-hawks 30 set init-mean-vision 5 set init-SD-vision 1.2 end to-report child-geno [geno1 geno2] ; reports a child's genotype given both parents' genotypes ; parents are a survior and a random other turtle of the same breed let x 0 let y 0 let geno 0 set x geno1 * geno2 ; produce a uniques selection criterion ifelse x = 1 ; AA x AA [set geno dom] [ ifelse x = 2 ; AA x Aa [ifelse random 2 = 0 [set geno dom] [set geno hetero] ] [ ifelse x = 3 ; AA x aa [set geno hetero] [ ifelse x = 4 ; Aa x Aa [set y random-float 1 ifelse y < 0.25 ; 0.25 prob AA [set geno dom] [ifelse y > 0.75 ; 0.25 prob aa [set geno rec] [set geno hetero ; else must be Aa ]]] [ ifelse x = 6 ; Aa x aa [ifelse random 2 = 0 [set geno rec] [set geno hetero] ] [ set geno rec ; aa x aa ]]]]] report geno end @#$#@#$#@ GRAPHICS-WINDOW 17 264 327 595 -1 -1 30.0 1 10 1 1 1 0 0 0 1 0 9 0 9 1 1 1 ticks 30.0 BUTTON 13 15 92 65 NIL setup\n NIL 1 T OBSERVER NIL NIL NIL NIL 1 BUTTON 92 14 169 64 NIL go\n T 1 T OBSERVER NIL NIL NIL NIL 1 PLOT 340 12 604 132 Camouflage Score Freq 0.0 40.0 0.0 50.0 true false "" "" PENS "default" 1.0 1 -2674135 true "" "histogram [camo] of mice" PLOT 604 13 866 133 Vision Score Freq 0.0 40.0 0.0 10.0 true false "" "" PENS "default" 1.0 1 -13345367 true "" "histogram [vision] of hawks" PLOT 340 177 603 297 Populations Generation Num 0.0 30.0 0.0 10.0 true true "" "" PENS "Mice" 1.0 0 -2674135 true "" "plot count mice" "Hawks" 1.0 0 -13345367 true "" "plot count hawks" PLOT 603 177 867 340 Phenotype Scores Generation Score 0.0 30.0 0.0 10.0 true true "" "" PENS "Camo" 1.0 0 -2674135 true "" "if count mice > 0 [plot mean [camo] of mice]" "Vision" 1.0 0 -13345367 true "" "if count hawks > 0 [plot mean [vision] of hawks]" SLIDER 15 180 171 213 init-mean-camo init-mean-camo 0 10 5 1 1 NIL HORIZONTAL SLIDER 173 184 330 217 init-mean-vision init-mean-vision 0 10 5 1 1 NIL HORIZONTAL SLIDER 16 214 172 247 init-SD-camo init-SD-camo 0 5 1.2 .1 1 NIL HORIZONTAL SLIDER 173 215 330 248 init-SD-vision init-SD-vision 0 5 1.2 0.1 1 NIL HORIZONTAL BUTTON 256 15 332 65 NIL reset NIL 1 T OBSERVER NIL NIL NIL NIL 1 SLIDER 15 148 171 181 init-mice init-mice 0 100 50 1 1 NIL HORIZONTAL SLIDER 173 150 330 183 init-hawks init-hawks 0 100 30 1 1 NIL HORIZONTAL BUTTON 170 15 255 65 5 ticks repeat 5 [go] NIL 1 T OBSERVER NIL NIL NIL NIL 1 MONITOR 340 132 425 177 mean camo mean [camo] of mice 1 1 11 MONITOR 602 132 688 177 mean vision mean [vision] of hawks 1 1 11 MONITOR 424 132 510 177 SD camo standard-deviation [camo] of mice 2 1 11 MONITOR 686 132 772 177 SD vision standard-deviation [vision] of hawks 2 1 11 MONITOR 340 297 474 342 mouse population count mice 1 1 11 MONITOR 509 132 601 177 range camo max [camo] of mice - min [camo] of mice 1 1 11 MONITOR 469 296 603 341 hawk population count hawks 1 1 11 MONITOR 773 132 866 177 range vision max [vision] of hawks - min [vision] of hawks 1 1 11 SWITCH 170 83 327 116 hawks-evolve? hawks-evolve? 0 1 -1000 SWITCH 15 83 171 116 mice-evolve? mice-evolve? 0 1 -1000 SWITCH 16 116 172 149 camo-dominant? camo-dominant? 0 1 -1000 SWITCH 170 115 327 148 vision-dominant? vision-dominant? 0 1 -1000 PLOT 603 340 818 476 Hawk Genotypes Generation Freq 0.0 30.0 0.0 1.0 true true "" "" PENS "AA" 1.0 0 -2674135 true "" "if count hawks != 0 [plot count hawks with [hawk-geno = dom] / count hawks]" "Aa" 1.0 0 -16777216 true "" "if count hawks != 0 [plot count hawks with [hawk-geno = hetero] / count hawks]" "aa" 1.0 0 -13345367 true "" "if count hawks != 0 [plot count hawks with [hawk-geno = rec] / count hawks]" PLOT 340 342 555 477 Mouse Genotypes Generation Freq 0.0 30.0 0.0 1.0 true true "" "" PENS "AA" 1.0 0 -2674135 true "" "if count mice != 0 [plot count mice with [mouse-geno = dom] / count mice]" "Aa" 1.0 0 -16777216 true "" "if count mice != 0 [plot count mice with [mouse-geno = hetero] / count mice]" "aa" 1.0 0 -13345367 true "" "if count mice != 0 [plot count mice with [mouse-geno = rec] / count mice]" PLOT 605 476 818 596 Hawk Alleles Generation Freq 0.0 30.0 0.0 1.0 true true "" "" PENS "Dom" 1.0 0 -2674135 true "" "if count hawks != 0 [plot (count hawks with [hawk-geno = dom] + 0.5 * count hawks with [hawk-geno = hetero]) / count hawks]" "Rec" 1.0 0 -13345367 true "" "if count hawks != 0 [plot (count hawks with [hawk-geno = rec] + 0.5 * count hawks with [hawk-geno = hetero]) / count hawks]" PLOT 340 476 556 596 Mouse Alleles Generation Freq 0.0 30.0 0.0 1.0 true true "" "" PENS "Dom" 1.0 0 -2674135 true "" "if count mice != 0 [plot (count mice with [mouse-geno = dom] + 0.5 * count mice with [mouse-geno = hetero]) / count mice]" "Rec" 1.0 0 -13345367 true "" "if count mice != 0 [plot (count mice with [mouse-geno = rec] + 0.5 * count mice with [mouse-geno = hetero]) / count mice]" MONITOR 555 342 605 387 AA count mice with [mouse-geno = dom] / count mice 2 1 11 MONITOR 555 386 605 431 Aa count mice with [mouse-geno = hetero] / count mice 2 1 11 MONITOR 555 430 605 475 aa count mice with [mouse-geno = rec] / count mice 2 1 11 MONITOR 818 340 868 385 AA count hawks with [hawk-geno = dom] / count hawks 2 1 11 MONITOR 818 386 868 431 Aa count hawks with [hawk-geno = hetero] / count hawks 2 1 11 MONITOR 818 432 868 477 aa count hawks with [hawk-geno = rec] / count hawks 2 1 11 MONITOR 555 508 605 553 Dom (count mice with [mouse-geno = dom] + 0.5 * count mice with [mouse-geno = hetero]) / count mice 2 1 11 MONITOR 555 550 605 595 Rec (count mice with [mouse-geno = rec] + 0.5 * count mice with [mouse-geno = hetero]) / count mice 2 1 11 MONITOR 817 505 867 550 Dom (count hawks with [hawk-geno = dom] + 0.5 * count hawks with [hawk-geno = hetero]) / count hawks 2 1 11 MONITOR 817 550 867 595 Rec (count hawks with [hawk-geno = rec] + 0.5 * count hawks with [hawk-geno = hetero]) / count hawks 2 1 11 @#$#@#$#@ ## WHAT IS IT? This simulation models coevolution of a predator-prey sytem. It is based on the board game **SIMULATING NATURAL SELECTION** by Robert P. Gendron from Indiana University of Pennsylvania. The model incorporates the following elements of a natural system: Variability, heritability, competition, predation, carrying capacity and differential reproduction. Users can set the intial values for adaptation scores, variability of adaptation scores and population size. The simulation produces behaviors that demonstrate directional selection, the coevolution of traits, genetic drift and predator-prey population cycles. ## HOW IT WORKS The two populations in the model are hawks and mice. Hawks have a vision score and mice have a camouflage score. Populations are intialized with user specified number, mean score and score variation. Individual mice and hawks are assigned a random genotype on setup. Each population is then randomly distributed in the world. Each tick in the model represents a discrete set of events that occur in the following order: 1. **PREDATION:** If a hawk and mouse are on the same patch and the hawk's vision score is greater than the mouse's camouflage score then the hawk eats the mouse, reproduces and dies (See 2 below). If there is a tie in the scores a coin flip determines if the mouse is eaten or survives. If there are many mice on a patch, the mouse with the minimum camouflage score is eaten. 2. **HAWK REPRODUCTION:** Each hawk that successfully eats produces two offspring as follows: **> If hawks-evolve? is ON:** Hawk vision **is** affected by mice camouflage. Each hawk reproduces with another random hawk. Each child's genotype is determined by their parents genotypes based on simple Mendelian probabilites. **If vision-dominant? is ON:** Homozygous dominant and hetrozygous children are assigned a vision score equal to the parent score _**plus**_ a random value between 0 and 1. Homozygous recessive children are assigned a vision score equal to the parent score _**minus**_ a random value between 0 and 1. **If vision-dominant? is OFF:** Homozygous recessive children are assigned a vision score equal to the parent score _**plus**_ a random value between 0 and 1. Homozygous dominant and hetrozygous children children are assigned a vision score equal to the parent score _**minus**_ a random value between 0 and 1. **> If hawks-evolve? is OFF:** Hawk vision **is not** affected by mice camouflage. Each hawk reproduces with another random hawk. Each child's genotype is determined by their parents genotypes based on simple Mendelian probabilites. Both children are assigned vision scores drawn randomly from the normal distribution defined by the init-mean-vision and init-SD-vision sliders. **>Both Conditions:** Each new hawk is assigned an age equal to the tick count when it is hatched. The parent hawk dies immediately after reproducing. If there are still mice on the patch where the new hawks are hatched, the newly hatched hawks get a chance to hunt and reproduce until all mice on a given patch with camouflage scores lower than hawk vision scores are eaten. 3. **HAWK STARVATION:** If a hawk does not eat within 2 ticks of being hatched it dies. 4. **MOUSE REPRODUCTION:** Mice that survive and are alone on a patch (i.e., no competition for resources from other mice) reproduce two offpring as follows: **> If mice-evolve? is ON:** Mouse camouflage **is** affected by hawk vision. Each mouse reproduces with another random mouse. Each child's genotype is determined by their parents genotypes based on simple Mendelian probabilites. **If camo-dominant? is ON:** Homozygous dominant and hetrozygous children are assigned a camouflage score equal to the parent score _**plus**_ a random value between 0 and 1. Homozygous recessive children are assigned a camouflage score equal to the parent score _**minus**_ a random value between 0 and 1. **If camo-dominant? is OFF:** Homozygous recessive children are assigned a camouflage score equal to the parent score _**plus**_ a random value between 0 and 1. Homozygous dominant and hetrozygous children children are assigned a camouflage score equal to the parent score _**minus**_ a random value between 0 and 1. **> If mice-evolve? is OFF:** Mouse camouflage **is not** affected by hawk vision. Each mouse reproduces with another random mouse. Each child's genotype is determined by their parents genotypes based on simple Mendelian probabilites. Both children are assigned camouflage scores drawn randomly from the normal distribution defined by the init-mean-camo and init-SD-camo sliders. **>Both Conditions:** The parent mouse dies immediately after reproducing. 5. **RANDOM DISTRIBUTION:** All surviving hawks and mice are randomly redistributed in the world and the the above steps are repeated. ## HOW TO USE IT 1. The **mice-evolve?** and **hawks-evolve?** switches determine if the mouse and hawk populations evlove in response to environmental pressures (On) or randomly (Off) 2. The **vision-dominant?** and **camo-dominant?** switches determine if improvements in each trait are dominant (On) or recessive (Off) 2. The **init**, **mean** and **SD** sliders set the initial population size (mice or hawks), the intial mean value of the adpatations (camouflage or vision) and the variation within the population for each adaptation (camouflage or vision), respectively. 3. The **Reset** button returns all settings to their default values. 4. Use the **SETUP** button to initalize the simulation to the values you set using the sliders and switches described above. Press the **GO** button to run the simulation continuously or use the **5 TICKS** button to advance the simulation 5 ticks at a time. ## THINGS TO TRY Use the model to experiment. Start by making changes to only one setting at a time. Run each experiment several times as the results may differ. Make note of these different outcomes and the frequency with which they occur. For each experiment be sure to explain what you think might be causing the results you obseve. Some suggested experiments are listed below (**NOTE:** All settings are assumed to be default EXCEPT those indicated): 1. Run the model using the default settings. 2. Set the init-hawks slider to zero. 3. Set both hawk and mice evolve? switches to off. 4. Turn off mice evolution only. 5. Turn off hawk evolution only. 6. Change the mean value of the mice camouflage value. 7. Change the variation (SD) value of the mice camouflage value. 8. Change the mean value of the hawk vision value. 9. Change the variation (SD) of the hawk vision value. 10. Change vision, camouflage or both to recessive. 11. Increase or decrease the mouse, hawk or both populations. 12. Try to get both populations to survive most of the time when mice-evolve? is off. ## THINGS TO NOTICE 1. What happens to the vision and camouflage scores under different settings? 2. How do these scores change relative to one another? 3. What happens to the vision and camouflage variation under different settings? 4. How do the populations change relative to one another? 5. Does either population go extinct? reach a carrying capacity? 6. Are there any notable trends in the allele frequencies? 7. Do any alleles become fixed / extinct? ## EXTENSIONS Play the board game (see link below) and explore the code to see how it works. ## RELATED MODELS In the NetLogo Library: 1. Bug Hunt Camouflage 2. Bug Hunt Coevolution 3. Bug Hunt Drift 4. Red Queen 5. Wolf Sheep Predation 6. Wolf Sheep Stride Inheritance ## CREDITS AND REFERENCES Dr Robert Gendron's Faculty Page at IUP: http://www.iup.edu/page.aspx?id=85437 A copy of the original board game directions: http://biology4teachers.com/Evolution/natural%20selection%20game.doc ## COPYRIGHT AND LICENSE Copyright 2013 Michael Zito. ![CC BY-NC-SA 3.0](http://i.creativecommons.org/l/by-nc-sa/3.0/88x31.png) This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line 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208 104 207 194 Rectangle -1 true false 195 60 195 105 Polygon -16777216 true false 238 112 252 141 219 141 218 112 Circle -16777216 true false 234 174 42 Rectangle -7500403 true true 181 185 214 194 Circle -16777216 true false 144 174 42 Circle -16777216 true false 24 174 42 Circle -7500403 false true 24 174 42 Circle -7500403 false true 144 174 42 Circle -7500403 false true 234 174 42 turtle true 0 Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210 Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105 Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105 Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87 Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210 Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99 wheel false 0 Circle -7500403 true true 3 3 294 Circle -16777216 true 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true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 5.0.5 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ default 0.0 -0.2 0 0.0 1.0 0.0 1 1.0 0.0 0.2 0 0.0 1.0 link direction true 0 Line -7500403 true 150 150 90 180 Line -7500403 true 150 150 210 180 @#$#@#$#@ 0 @#$#@#$#@