03 - Communication & Social Behaviour

Communication

process in which a specialized signal produced

by one individual affects the behaviour of another individual

Signal

an evolved trait that is selected for its effect on the behaviour of the recipient

Cue

consistent aspects of the environment that can guide behaviour of individual in way that enhances its fitnes

already present in the environment and the receiver evolves to recognize them because it benefits the receiver to do so≈

channel

signaler sends signals through channels to reciever

types of channel

vision, audition (sound), chemical, touch, electrical field

outcome when when signaler sends positive and recivers recieves positive

mutualistic

eg work in cooperation

outcome when when signaler sends positive and recivers recieves negative

manipulative

outcome when when signaler sends negative and recivers recieves positive

altruistic

outcome when when signaler sends negative and recivers recieves negative

spiteful

pretty rare

eg bacteria lyse themselves to kill less related bacteria

Sensitive period

a critical period in an organism’s development during which the

nervous system is especially sensitive to certain environmental stimuli

development of behaviour onset of sensitive period

•Triggered by external stimuli (presence of ‘teacher’) and by

development of nervous system (ability to perceive/respond to stimuli)

development of behaviour decline in sensitive period

• Ends when an organism matures à maturation triggers hormones to signal end of period of learning

• Ends once individual has achieved goal à e.g., young birds stop learning once have successfully learned songs

Ritualization

the alteration of a behaviour in ways that

reduces the chances of it being misunderstood by recipients

Ritualization involves

1. Increasing the conspicuousness of the behaviour

2. Reducing the amount of variation in the behaviour so it can be immediately recognized

3. Increasing its separation from the behaviour’s original function

when is a signal likely to become ritualized

• Often in conflict situations (threat, territoriality, reproduction)

• Reduces ambiguity of signal à message is standardized, more

efficient, less likely to be misread by recipient(s

what can signals say to reciever

1. Recognition of social group members

2. Mate attraction (i.e., bringing a mate to your location)

3. Courtship and act of mating (convincing )

4. Maintaining social bond

5. Alarm

6. Aggregation

7. Agonistic encounters ßsocial behaviours related to fighting

8. Share information about resources

Allogrooming

social grooming, can be for hygiene or conflict

resolution (appeasement

Agonistic behaviour

social behaviour that involves aggression and submission

signals of Agonistic behaviour

a) Aggression (threats, attacks)

b) Submission (appeasement, avoidance)

Cooperation

Behaviors that benefit recipients and that have been selected for because they benefit recipient

must communicate w each other

Eusocial organisms

colonial, multigenerational organisms with

extreme cooperative brood care (often involves sterile worker castes

eg ants

Altruism

A type of cooperative behavior that increases

another individual’s fitness at a cost to the actor’s fitness

hypothesis to explain altruism

By-products benefits

Manipulation

Reciprocity

Kin selection

Evolutionarily stable strategy

behaviours that persist in a population over time.

By-products benefits

acts in which both actor and recipients benefit immediately (i.e., are mutualistic acts!)

more benefit if done together

E.g., Cooperative hunting

• Consider an animal that can capture small prey alone, and larger prey in groups (lions, wolves)

• Cooperation is ESS if they get a larger net benefit (B – C) by working together then by hunting alone

Manipulation

recipients trick actors of behaviour into ‘altruism’, selection is acting on recipient to encourage manipulation, not on actor to act altruistically

E.g., Brood parasitism

Many birds identify their young based on location (e.g., inside of nest)

•Brood parasites egg dump into nests of host species à causing host

parent to raise young

Reciprocity

trading of altruistic acts between two individuals (mutualism with delayed benefit), over time, both participants should experience NET GAINS in fitness.

E.g., Blood sharing in vampire bats (Wilkinson)

Donors and recipients recognize each other individually (no need

to be related)

• Sufficient pairwise interactions that there are interchanges of

roles and a net benefit to ALL

• Benefit of receiving aid outweighs cost

Relative fitness

fitness of specific individual as compared to the average of the

population that individual lives in (often measured as relative number of offspring)

Kin selection

altruism aimed at close relatives

Parental care

altruism aimed at descendant offspring

Hamilton’s rule

an altruistic allele will spread if the ‘weighted’

benefit to the recipient is greater than the cost to the actor

Br – C > 0

Br – C > 0 what does each thing stand for

b = Benefit to recipient

Coefficient of relatedness (r) = the relatedness between the actor

and the recipient, measured as the proportion of alleles that are

identical in them due to their shared ancestry

c = Cost to actor (often measured in LOST offspring)