Thursday 16th September - Conflict

Question 1

1. Why do animals come into confilct with each other?

2. When animals do come into conflict, what does it look like?

a. Do they use their weaponry to full extent in each interaction?

b. Ritualised (restrained) aggression?

Answer 1

1.

• Competition for resources, particularly when resources are limited.

2.

Overt aggression?

• Do they use their weaponry to full extent in each interaction?
• Ritualised (restrained) aggression?
• They don’t ‘fight to kill’ in every conflict situation.

Example: Rattle snakes fight but to not bite and inject poison to each other.

Question 2

What is ‘Agonistic behaviour’ ?

Answer 2

‘All conflict behaviour between conspecifics’

• Often talking about unrelated animals
• Including threats, submission, chases, physical fighting

(Not predation between different species)

Example: Chimpanzee or wolves competing for the role of Alpha

Question 3

What is Aggressive/Offensive behaviour?

Answer 3

‘Apparently intended to inflict noxious effects/destruction on another organism’

• Biting, kicking, chasing, display
• An animal excludes another from a resource

Question 4

What is Submissive/Defensive behaviour?

Answer 4

‘Yielding to another indivisual’

- Ducking, running away, hiding, display.

-Animal is excluded from a resource

(Not always the same: sometimes defensive behaviour is the prelude to an offense)

Question 5

Analyse these behaviours

Answer 5

Pic 1: Horse is showing offensive/aggressive display

Pic 2: Contact and aggression

Pic 3: Submissive/Defensive display

Pic 4: Animal fleeing

Question 6

1. Animals generally don’t fight intensively all the time, why?

2. Conflict occurs at times, when?

Answer 6

1. It is costly

(Time taken away from parenting/foraging)

2. When animals live together and resources are limited.

(Lack of food/water/breeding partners etc)

Question 7

What are the three main means of limiting over aggression?

Answer 7

1. Ritualised fighting

2. Dominance hierarchies

3. Territoriality

Question 8

Ritualised Fighting

Example: Red Deer

Stage 1 ?

Stage 2?

Stage 3?

Answer 8

Stage 1: Roaring

Stage 2: Parallel walking (Sizing up like Sharks do)

Stage 3: Antler clashing

Less than 25% of contests reach antler-pushing

• 25% Minor cuts and bruises
• 6% obtain permanent injuries

Question 9

Why this Ritualised aggression?

Answer 9

Its Dangerous - risk of injury

Evolutionary point of view

• Animals fighting seriously might win frequently. Thus, favoured by natural selection.
• Increased number of serious-fighters, leading to more serious fights = more injuries
• Restrained fighters (who flee) might end up having an advantage due to less injuries.

Question 10

Hawk-Dove Game Theory

Theoretical model, examines the question of

‘Why don’t animals always fight seriously for valuable, limited resources’ ?

Answer 10

• Helps to understand costs/payoffs of different interactions.
• Predicts an animal’s optimal behaviour, accounting for others’ behaviour.

Strategies (Sets of behaviours used by player assumed to be heritable.

• Currency here = impacts on fitness (e.g., no. offspring, energy).

Question 11

Hawk-Dove Game Theory

Explain the differences between the approach of the Hawk and the Dove.

Answer 11

Hawks = Unrestrained fighters (serious)

-Will continue to esculate a conflict until they win or are injured and the losers pay a cost.

-

Doves = Restrained fighters (flee from hawk, display to dove)

-Display to opponent, but cede the resource to an aggressive opponent.

Question 12

Hawks

V ?

W ?

D ?

Answer 12

V = Value of resouces

W = Cost of being Wounded

D = Cost of displaying

Hawk vs. Hawk = 50/50

Dove vs. Dove = 50/50

Same behavioural strategy = equal chance of winning

Question 13

Pay off matrix

When an animal is taking this behavioural approach to a conflict sitatuion vs another behavioural strategy, what is the pay off they engage in?

(V W D)

Answer 13

Question 14

What is an ‘Evolutionary stable strategy’ ?

(EES)

Answer 14

‘A strategy [set of behaviours] that, when most animals in a population adopt it, cannot be ‘beaten’ by any other strategy’

No other strategy confers more fitness benefits to those animals

• With the values in the previous example, it is a combination of those two strategies that is stable.
• All hawks/all doves is not an ESS
• This mix = Mixed ESS

(Average payoff for each strategy is the same, resulting in stable proportions of each type of behaviour)

*See reading for more details

Question 15

Intensity of aggression is driven by value of winning access to resource relative to the costs of fighting

Answer 15

E.g. Red Deer.

• Value of access to females changes over time.
• When value is highest (most conceptions), more fights

*Fights peak around peak of conception in females time frame.

Question 16

The costs/benefits balance of serious fighting is not the only reason why unrestrained fighting doesn’t occur all the time.

What other factors are there?

(individual variation)

Answer 16

- Strength Varies

Stages of ritualised fighting may serve to assess opponents’ strength.

• E.g., Red Deer: roaring, parallel walking.

- Some resources are more valuable to some animals

• Motovation

- ‘Loser effects’ - Once an animal has won/lost, this outcome can effect future outcomes

• E.g., if a socially isolated male mouse has some easy wins against less aggressive mive, it will start to attack any males in sight. And vice versa.
• E.g., Blue footed boobies.

Question 17

Blue footed boobies

Explain their winner/looser effect

Answer 17

• Can be aggression between nest males
• If older chicks are more aggressive and dominant early on, then they are more likely to win interactions against younger, submissive chicks.

Examples

• Tested to examine winner/loser effects in isolation from each other.

– Dominant chick vs. inexperienced chick.

– Submissive chick vs. inexperienced chick.

• Results: Effects waned after ~4 h (10 day obs.).

– Dominants = more aggressive.

– Submissives = less aggressive.

Question 18

When might resources be more valuable to some animals?

Answer 18

Dominance Hierarchies

Animals in stable social groups are likely to compete for resources repeatedly – so they form relationships.

• Dominance = when an animal has priority access to a limited resource. – Submissive animals are supplanted by, or simply cede access to, dominant animals.

– Reduces overt aggression in social groups

Dominance hierarchy = the overall arrangement of dominant/submissive individuals in a group.

• These can change according to conditions and over time.

Question 19

Dominance Hierarchies

Explain the four types dominance hierarchies, use diagrams to aid your explanations.

Answer 19

1. Despotism: one animal is dominant over all others

(who are equally-ranked). – E.g., unfamiliar mice put together.

2. Linear: – ‘Pecking order’. E.g., chickens. •

3. Triangular relationships

4. Alliances: – ‘Coalitions.’ E.g., primates, dolphins.

Notes:

• Few hierarchies are perfectly linear.

- Dominance reversals are often seen.

• Individuals in groups may have equal status.

Question 20

Dominance Heirarchies

To derive a dominance hierarchy, we look at dyadic relationships.

• Observe pairs of animals and determine who supplants who.
• Arrange in a matrix.
• Re-arrange so that the animal who is never supplants is at top of matrix, following this order until the one who is always supplanted is at the bottom.

Answer 20

Note:

This procedure of deriving hierarchies can be deceptive. There’s a high probability that data can be arranged into a hierarchy when none exists. (Appleby, 1983 cited in Martin & Bateson, 1993.)

Question 21

Dominance Hierarchies

1. Benefits of being dominant in rank? (2)

2. Benefits of being subordinately-ranked? (many)

Answer 21

Benefits of being dominant in rank?

• Increased access to food.
• Increased access to mates.

Benefits of being subordinately-ranked?

• Stable hierarchies benefit subordinate animals too – less conflict.
• Risks of leaving group may be greater cost than staying.
• Some dominant animals have higher glucocorticoid levels

(but some do not).

• If in a group containing relatives, could gain some indirect fitness through helping raise siblings, etc.
• Sometimes gains access to resources. – Winning / sneaking.

Question 22

Dominance Hierarchies – Caveats

Remember - Relationships between animals can change with environmental conditions and over time.

Question: What are some examples of situations in which the order of access to resources may be altered?

Common mistake is to place too much emphasis on hierarchies.

• Status of each individual is not fixed, nor a general characteristic of that animal.
• Hierarchies are often fluid and can change quickly.
• Hierarchies are sometimes correlated with geography, e.g., an animal’s rank increasing towards the centre of its home range.

- Hierarchies derived from one type of interactions (e.g., access to food) may be different when considering other interactions (e.g., access to mates).

Question 23

Akos et al. (2014).

Leadership and path characteristics during walks are linked to dominance order and individual traits in dogs.

• Examined leadership in a group of household dogs during walks.
• Found that leadership roles were interchanged, but long-term there were consistent patterns.
• Leadership was associated with dominance rank (as assessed prior via owner questionnaire).

– Also positively correlated with age, responsiveness to training, controllability, and aggression towards people.

Question 24

Example – ‘Leadership’ in Dogs

Note:

This is a complex topic.

- This concept is often misapplied with domestic animals – with negative welfare consequences.

Often misapplied to Domestic Animals

(My dogs sleeps on the bed so ‘it means’ she is trying to be alpha)

https://www.scientificamerican.com/video/canine-study-seeks-top-dogs-for-leadership-role/

Question 25

Territoriality

Animals often get into conflict defending space.

(Although not all animals defend a territory.)

1. Define ‘Territory’

Answer 25

Territory = area that is defended against intruders.

There are economics involved in defending a territory.

• Territories are often defended when resources are present in reasonable amounts and somewhat clustered.
• If resources are abundant/scarce, it maybe unnecessary/too much cost to defend territory.

Question 26

Territoriality

What are the benefits/costs to defending a territory?

Answer 26

Exclusive use of resources.

• Reduced costs associated with this.

Need to patrol boundaries, costly.

– Animals often signal, scent mark to maintain boundaries.

– Larger territories can mean more intruders.

• Larger boundaries = more costly to defend (time, number of intruders). –
• Time away from other activities

Note: animals can be dominant on their territory, but not when off it.

Question 27

Explain the ‘Deer Enemy’ effect.

Answer 27

• This is when familiar neighbouring animals often respond in a less aggressive way vs an intruder.
• These two animals live in established territories with some familiarity of each other, when they encounter each other they react less aggresively as apposed to a complete stranger or unknown neighbour.