Bystander effects

1. Bystander effects • Ok, lots of support for winner and loser effects • How about bystanders? • What affect does seeing another win or lose have on YOUR chances of winning or losing? • What does watching give you?

2. Swordtail fish • If you see an aggressive encounter, you can learn valuable information for the future. • Test for these effects with control where bystander could not see outcome of combat • Treatment where bystander could see but combatants couldn’t What happens when you now pit bystander against winner or loser?

3. Outcomes • Where bystander could see outcome, tended to avoid contest with winner more than bystander that could not see contest. • AND not escalate as often,

4. Outcomes • Bystanders that saw outcomes and those that did not, treated losers about the same way. • But length of aggressive encounter made a difference. • Initiated more against losers that left contest quickly.

5. What does this mean? • Bystander can use information to its advantage. • Judges fighting skills of both combatants based on not only on who wins or loses but how escalated the fight becomes. • Future aggressive actions then affected by this information.

6. Audience Effects • Here we are looking at how onlookers affect the outcome of the conflict. • Chimpanzees: Aggressor screams and victim screams. • In mild encounters, victims don’t scream any longer with or without audience • In severe encounters, victims scream longer and louder with an audience.

7. Outcome • Who is in the audience makes a difference! • If there was an equal or higher ranking individual to the aggressor, was present. Why? intervenes and breaks up fight.

8. Summary • In this case combatants seem aware of who is in the audience and adjust their behavior accordingly. • Area rich in research possibilities to see not just how they may adjust behavior but how audience might alter outcome. • Would you fight harder depending on who is watching??

9. Aggression summary • Aggression behavior is over resources • Is linked with testosterone and various other hormones. • Can be modeled with game theory where outcome depends on value of the resource and the costs associated with trying to get that resource. • Outcomes often decided on physical advantage but also depends on how each combatant values the resource.

10. Aggression summary • Can result in an “ordering” of society but not a peaceful one.

11. “Pure behavior” • Before we move on to behavioral ecology, a few other behavioral categories to cover. • First of these is disease and animal behavior. (Chap 16). • As we will see with other “threats” to health and life, many animals have developed behaviors aimed at reducing their chances of catching diseases. • Here we will look at a few of them.

12. Avoidance of disease • Avoidance of habitats -Tree frogs: were able to determine presence of snails (intermediate host of trematode parasite) and avoid laying eggs in these ponds.

13. Avoidance of individuals • Bullfrogs: In tadpole stage, evidence that uninfected individuals preferred to associate with other uninfected ones, avoided inflected individuals. • How did they tell? • Seems chemical cues were used. • Others? Often see avoidance of “unhealthy” individuals. Part of the sexual test is a health check!

14. Self - medication • Seems we are not the only ones who like to self medicate! • Two broad categories • 1) Preventative • 2) Therapeutic

15. Preventative medicine • Many species use potentially anti-bacterial plant substances in their nests. • Starlings add fresh herbs – led to higher body weight of fledglings. • Many primate species eat clay, dirt, and rocks to reduce indigestion, as an antidiarrheal agent, absorb dangerous plant compounds

16. Preventive medicine • “Anting” by birds and mammals: rubbing crushed ants on feathers and fur. Formic acid aids against tick infections • “Fur rubbing”: many primates rub fruits, leaves, and vines on their fur, which have antimicrobial effects.

17. Therapeutic self-medication • Use of leaves by Chimpanzees against tapeworms. • Other primate do the same. • Dogs and cats eating grass.

18. Summary • Growing evidence that many species self medicate, • Obvious evolutionary advantage to individuals who “discover” the use of these medicines. • Often with similar substances we commonly use today. In fact, starting to try and identify others that are being used that we might be able to use!

19. Next: Personalities! • Used to consider people who thought animals had “personalities” were them selves “personalities”!!! • But more and more research is demonstrating that indeed there are individual differences in behaviors or personalities. • Not surprising in that we have been talking about natural variation in most behaviors.

20. How do personalities differ? • One common way is Boldness vs Shyness • Boldness: tendency to take risk in familiar and unfamiliar situations • Shyness: reluctance to take such risks or reluctance to engage in unfamiliar activities at all.

21. Why would we find both? • IF we think of evolution as the survival of the fittest, often hard to see why we would have a range of any trait. • IF we consider survival of the adequate, then in some cases being shy has advantages and some cases being bold.

22. Evidence for boldness and shyness • Do we really find these personality differences? • Pumpkinseed sunfish: • Trapped vs seined • Trapped bolder willing to investigate

23. Were they? • Trapped adjusted more quickly

24. Guppies • Boldness and predator inspection: • Found there were consistent differences • Always bold • Always shy • Bold are colorful

25. Why be bold? • It seems to impress the females!

26. Is she really?? • Will mate with bold males regardless of color

27. Other than boldness and shyness? • What other traits vary regarding personalities? • Gosling (1998) found five aggregate traits in Hyenas: • 1) assertiveness • 2) excitability • 3) Human-directed agreeableness • 4) sociability • 5) curiosity

28. Octopus?? • Turns out they have personalities! • 1) Active vs inactive • 2) anxious vs calm • 3) bold vs inhibited.

29. Ruffs • Personalities related to physical differences. • “independent” males vs “Satellite” males • Dark and larger vs light and smaller • Independent set up territories. • Satellites needed to attract females.

30. Last: Coping styles • Related to bold and shy but relative to how they respond to stress in the environment. • Proactive vs reactive • Proactive: likely to remove negative stimuli from their environment • Reactive; more likely to hide from new negative stimuli

31. Lab rats • Can breed for proactive vs reactive • Proactive more likely to show aggression toward intruder, reactive will hide • Proactive rats will try to remove or neutralize a negative stimulus, reactive ones will just avoid the area where the stimulus is.

32. Summary • Good evidence that personality differences exist: boldness/shyness most studied

33. Fear • Recognize it in humans • TV, Movies, Books, etc. play upon our fears! • We love to be scared!! • But what about other animals? • Often reluctant to recognize it: too anthropocentric!

34. Fear • Talked about aggression as a behavior • Widely accepted as a behavior of animals, no anthropocentric overtones.

35. But why does aggressive behavior work? • Needs reciprocal reaction or behavior! • Call it submissive behavior • But it is FEAR!

36. Intraspecific conflicts • Why does one win and another lose? • What makes the one back down? …..Fear If not…. fight to the death!

37. Imagine if someone was trying to kill you! • Would we call it submissive behavior?

38. What is it? • No other way to describe it except… Fear!

39. One of the most prevalent behaviors • Considering what we have talked about regarding aggression and what we will talk about regarding predation… • Fear is probably THE one most likely behavior an organism will experience! • Also, as you will see, is probably the most influential behavioral force in ecology

40. So fear exists • Many felt it was too anthropocentric to ascribe fear to animals: • Talked about “escape” and “avoidance behaviors” • But these are the behaviors that are produced by fear.

41. Today? • More acceptable to talk about fear in animals • Still not mainstream • No mention of it in most behavioral texts. • Yet whole chapters devoted to aggression! • So lets look at fear as a behavior

42. Definitions • Two important concepts regarding fear (from psychology) • 1) motivation • 2) personality

43. Motivation • Fear and anxiety: emotional states that are induced by the perception of any actual danger (fear state) or potential danger (anxiety state) and which are characterized as a feeling of insecurity

44. Personality • Fearfulness: personality or temperament trait defining the general susceptibility of an individual to react to potentially threatening situations. (Just how fearful or anxious you will be)

45. Five basic questions • Survival function “What good is it” • Immediate stimuli “what causes it” • Development “How does it develop” • Phylogeny “How does it change” • Ecological function “How does it affect others”

46. Evolutionary advantage? • Fear definitely has survival value to wild animals! • Most important threats of injury and death individual encounters are from predators and competing/attacking conspecifics. • Defensive reactions increase the chances of survival. • If you don’t fear your predators, your dead!!

47. What causes fear response? • Classic is there is a stimulus associated with behavior • What is nature of frightening stimuli? • Gray in 1979 classified fear-producing stimuli into 5 subdividsion

48. Subdivisions of fear stimuli • 1) dangers related to evolutionary history • 2) dangers related to novelty • 3) stimuli you learn are related to danger • 4) Intensity of the stimuli • 5) stimuli arising from interactions with conspecifics.

49. 1. Evolutionary history • “Innate” fear responses • Usually specific stimuli that are related to ecology of species, many cross species boundaries • Physical dangers: fear of heights, fear of darkness, fear of dead things. • Fear of predators: silhouettes of hawks illicit responses in nestlings

50. 2. Novelty • Apart from established innate fear stimuli • Exposing animals to a novel object has been found to be most potent stimulus leading to negative emotional response. • Behavioral reaction similar to that induced by negative stimuli such as electric footshocks! • Animals are inherently afraid of NEW things!