1. Agent-Based Modeling and Simulation (ABMS) Bertan Badur badur@boun.edu.tr Department of Management Information Systems Boğaziçi University

2. Collectives Chapter 16 of Agent-Based and Individual-Based Modeling: A Practical Introduction, by S. F. Railsback and V. Grimm NetLogo User Menual

3. Outline.

4. 16.4 A Wild Dog Modfel with Packs

5. Entities, States, Scales Agents: –dogs, dog packs, disperser groups State variables: dogs –age, sex, pack or disperser group, social status –social atatus: “pup”: age less then one “yearling”: age between 1 and 2 “subordinate”: age greater then 2 but dog is not an alpha “alpha”: dominant sex in a pack “disperser”: belong to a disperser not a pack dog packs –list or agent set of dogs disperser groups: –sex, agnet set of members

6. NetLogo Code globals [n-telemar] turtles-own [bank-bal] to setup ca ] reset-ticks end to go tick if ticks > yers-to-sim [stop] end

7. NetLogo Code breed [dogs dog] breed [packs pack] breed [disperser-groups disperser-group] dogs-own [ age sex status my-pack my-disperser- group ] packs-own [ pack-members ] disperser-groups-own [ sex group-members ]

8. Initialization 10 packs, no disperser groups number of dogs in each initial pack –Poisson – mean 5 sex: uniformly age: uniform intergers 0 – 6 social status: according to age alpha: for each sex, randomly among subordinates

9. NetLogo code (1) create-packs initial-num-packs [ setxy random-xcor random-ycor set shape "box" let num-dogs random-poisson initial-mean-pack-size hatch-dogs num-dogs [ set headıng random 360 fd 1 ifelse random-float 1.0 < 0.5 [set sex "male" ] [set sex "female"] set age random 7 set my-pack myself set-my-status ] ; end hatch-dogs

10. NetLogo code (2) set pack-members dogs with [my- pack = myself] update-pack-alphas ] ; end of create-packs

11. set-my-status to set-my-status ; dog procedure if age = 0 [set status "pup"] if age = 1 or age = 2 [set status "yearling"] if age > 2 [set status "subordinate"] end

12. update-pack-alphas to update-pack-alphas let can-alpha-males pack-members with [sex = "male" and status = "subordinate"] if any? can-alpha-males [ ask one-of can-alpha-males [set status "alpha"] ] let can-alpha-females pack-members with [sex = "female" and status = "subordinate"] if any? can-alpha-females [ ask one-of can-alpha-females [set status "alpha"] ] end

13. setup set years-to-sim 100 set carry-cap 60 set initial-num-packs 10 set initial-mean-pack-size 5

14. Process Overview and Scheduling (1) 1- age and social status updates –age is incremented –social status is updated –each pack updates its alpha –if not having an alpha a subordinate is selected 2- Reproduction –alpha male and female or no reproduction –N: total number of dogs – not newly born –carrying capacity: 60 –P: probablity of reproduction –P = 0.5 when N is 0.5 of carrying capacity –P = 0.1 whn N is carrying capacity

15. 3-Dispersal –if nosubordinate – no disperser groups –if one subordinate withprob 0.5 for a disperser group of one member –if more then one subordinates of thesame sex – always form a disperser group –dogs no longer belong to pach 4- Dog mortality probabilities: –0.44: disperser 0.25: yearlings, 0.2: subordinates and alphas, 0.12: pups 5- Mortality of collectives: –no member then collective dies –for packs only pups die ansd packs removes

16. 6- Form pack –disperser groups with opposit sex and from different packs –how namy times a group meets another poisson number of other groups –if meets 64/% forms a pack set status to disperser update alpha remove disperser groups 7-outputs –plots of number of dogs, disperser groups and packs

17. NetLogo Code - go to go tick if ticks > years-to-sim [stop] ask dogs [ set age age + 1 set-my-status ] ask packs [update-pack-alphas] ask packs [reproduce]

18. NetLogo Code - submodels ask packs [ disperse ] ask dogs [ do-mortality ] ask packs [ do-pack-mortality ] ask disperser-groups [ if count group- members = 0 [die] ] ask disperser-groups [ do-pack- formation ] update-output end

19. reproduce to reproduce if ( any? pack-members with [status = "alpha" and sex = "male"] ) and ( any? pack-members with [status = "alpha" and sex = "female"] ) [ let n-dogs count dogs let p logistic-func n-dogs if random-float 1.0 < p [ let num-new-pups random-poisson 7.9

20. reproduce hatch-dogs num-new-pups [ set headıng random 360 fd 1 ifelse random-float 1.0 < 0.55 [set sex "male"] [set sex "female"] set age 0 set status "pup" set my-pack myself set pack-members (turtle-set pack-members self) ] ; end of hatch ;set pack-members dogs with [my-pack = myself] ] ; reproduce ] ; any alpha end

21. logistic-func to-report logistic-func [num] let z a + b * num report ( exp z ) / ( 1 + exp z) end

22. add to setup set d ln (0.1 / 0.9) set x2 carry-cap / 2 set x1 carry-cap set b d / ( x1 - x2 ) set a d - ( b * x1 )

23. do-mortality to do-mortality if random-float 1.0 < pup-mortality-rate and status = "pup" [die] if random-float 1.0 < yearling-mortality-rate and status = "yearling" [die] if random-float 1.0 < subordinate-mortality- rate and status = "subordinate" [die] if random-float 1.0 < alpha-mortality-rate and status = "alpha" [die] if random-float 1.0 < disperser-mortality-rate and status = "disperser" [die] end

24. add to setup set pup-mortality-rate 0.12 set yearling-mortality-rate 0.25 set alpha-mortality-rate 0.20 set subordinate-mortality-rate 0.20 set disperser-mortality-rate 0.44

25. do-pack-mortality to do-pack-mortality if count pack-members = 0 [die] if count pack-members = count pack-members With [status = "pup"] [ ask pack-members [die] die ] end

26. disperse (1) to disperse let my-subordinates pack-members with [status = "subordinates"] if not any? my-subordinates [stop] if count my-subordinates with [sex = "female"] = 1 [ if random-float 1.0 < 0.5 [ create-disperser-group-from my-subordinates with [sex = "female"] ] if count my-subordinates with [sex = "female"] > 1 [ create-disperser-group-from my-subordinates with [sex = "female"] ] if count my-subordinates with [sex = "male"] = 1 [ if random-float 1.0 < 0.5 [ create-disperser-group-from my-subordinates with [sex = "male"] ]

27. disperse (2) if count my-subordinates with [sex = "male"] = 1 [ if random-float 1.0 < 0.5 [ create-disperser-group-from my- subordinates with [sex = "male"] ] if count my-subordinates with [sex = "male"] > 1 [ create-disperser-group-from my- subordinates with [sex = "male"] ] end ; to disperse

28. create-disperse-group-from (1) to create-disperser-group-from [some-dogs] hatch-disperser-groups 1 [ set group-members some-dogs set sex [sex] of one-of some-dogs set shape "car" set headıng random 360 fd 2

29. create-disperse-group-from (2) ask some-dogs [ set my-disperser-group myself set status "disperser" set color green move-to my-disperser-group set headıng [headıng] of my-disperser-group fd 1 + random-float 2 ] ; end of ask some-dogs

30. create-disperse-group-from (3) let dogs-former-pack [my-pack] of one-of some-dogs ask dogs-former-pack [ set pack-members pack-members with [status != "disperser"] ] end

31. to do-pack-formation let num-groups-met random-poisson count ( disperser- groups ) - 1 repeat num-groups-met [ let can-group-merge one-of other disperser-groups if any? can-group-merge [ if [sex] of can-group-merge != [sex] of myself and ( [my-pack] of one-of [group-members] of can- group-merge = [my-pack] of one-of [group-members] of myself ) and random-float 1.0 < 0.64 [merge-disperser-groups myself can-group- merge] ] end

32. merge-disperser-groups to merge-disperser-groups [disperser-group1 disperser-group2] hatch-packs 1 [ set pack-members [group-members] of disperser-group1 set pack-members (turtle-set pack-members [group-members] of disperser-group2 ) ask pack-members [ set status "subordinate" set my-pack myself update-pack-alphas ] ask disperser-group1 [die] ask disperser-group2 [die] end