How is communication adaptive?

1. How is communication adaptive?

2. 6/4/08: Animal Communication: Adaptationist perspective of communication Lecture objectives: • Be able to tell if a signal is adaptive, honest, or deceptive • Generate hypotheses and predictions about the relationship between components of a signaling system (sender, receiver, illegitimate sender, illegitimate receiver) Signal

3. How is signal-producing adaptive for the sender? Sender Receiver Signal

4. Example: How is a raven’s food call adaptive? H1: Call recruits family members to foodH2: Call recruits a coyote to open up the moose carcassH3: Call recruits others to reduce the risk of predation through the dilution effectH4: Call recruits other ravens so that all can overwhelm territory owners Obs1: Call at open carcassesObs2: Call when lots of ravens are already thereObs3: Birds at kill are unrelatedObs4: Pairs at kill were usually quiet

5. How does natural selection shape the sender’s signals? Sender Receiver Signal Illegitimate Receiver

6. Example: illegitimate receivers have shaped the begging calls of bird nestlings Hypothesis: The higher frequency calls of ground-nesting birds Silent Tree nesting Ground nesting Prediction: Ground nests with ground nest begging calls will have _____________ than ground nests with tree nest begging calls

7. Example: illegitimate receivers have shaped the calls of great tits Hypothesis: The tit’s “seet” alarm call has evolved properties Prediction: Unrelated species should

8. Example: illegitimate receivers have shaped the calls of male tungara frogs Whine Whine-chuck ? Hypothesis: Bats make the whine-chuck call especially costly for males Prediction 1: Prediction 2:

9. Are signals honest? Sender Receiver Signal

10. What might maintain honesty?(or in other words, why not cheat?) Selection should favor Cheating might hurt There is a (handicap principle – reliable signals should be costly to produce)

11. How is a receiver’s response to a signal adaptive? Sender Receiver Signal

12. A challenger often gives up after a mere threat How is this adaptive for the winner? How is this adaptive for the loser?

13. Example: Giving up early can be adaptive for the “loser” of antlered flies Hypothesis: antlered flies measure body size to determine Predictions:P1: P2:

14. Example: Giving up early can be adaptive for the “loser” of male European toads Observation: Body size influences the pitch of a male’s croak Hypothesis: males can judge the size of a rival by his croak Prediction:

15. How can deception evolve? Sender Deceptive Signal Receiver Deceptive signal Illegitimate Sender

16. Example: female Photirus fireflies deceive male Photinus fireflies Who is the sender? What is the signal? Who is the receiver? Who is the illegitimate sender?

17. What might maintain deception?(or in other words, why do receivers fall for lies?)