ANIMAL COMMUNICATION. What is it??

Transcription

1 ANIMAL COMMUNICATION What is it??

2 Bare Minimum for Communication SENDER produces a stimulus e.g. movement odor sound display etc. RECEIVER sensory neurons detect the stimulus e.g. vision olfaction audition etc. PNS Receiver brain interprets signal CNS

3 "What is communication"? Not a trivial question 1) Must communication signals be intentional? 2) Does the sender have to be intentionally "behaving"? 3) Must they be beneficial? To whom? 4) Is communication only INTRAspecific?

4 5) Is animal communication essentially different than human communication? 6) Does the receiver have to show an overt response to the signal?

5 General Model of Communication illegimate sender e.g. viceroy Sender e.g. male monarch butterfly Signal wing colors Receiver Female monarch? Bird predator? Nontarget Receivers e.g. male monarchs

6 Comments about using the model: 1) Sending or receiving does not have to be conscious, voluntary, or "neural". 2) Sender/receiver usually same species but may not be. 3) The signaling is normally advantageous to sender may or may not be to the receiver. 4) Upon receiving a signal, the receiver's behavior changes in some way. 5) Signals have receiver-specific meaning

7 SOURCE OF MEANING?? What is it about a signal that confers meaning?? SIGNAL MODULATION Dictionary Def. Modulate to varythe amplitude, frequency, or phase of a signal

8 Signals are varied or MODULATED which gives information richness. Modulated signals would include those that are i) DISCRETE (binary = 2-state = digital) ii) GRADED (analog) iii) COMPOSITE (of discrete & graded)

9 Discrete Signals - simplest type of modulation: *on-off, yes-no, presence-absence, etc. *signals don't vary in intensity Examples of discrete signals? *head-bobbing in lizard courtship displays? *fireflies at night

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11 Graded Signals vary continuously. EXAMPLE: crest-raising in Steller's Jays.

12 Graded signals may vary qualitatively or quantitatively. EXAMPLE: bird song qualitative = pitch variation (low to..high) quantitative = volume (soft.to.loud)

13 Composite signals combine discrete & graded. EXAMPLE: greeting & threat displays in zebras.

14 FUNCTIONS OF COMMUNICATION We'll discuss only 2: alarm communication communicating food location I) ALARM COMMUNICATION - group-living animals alert group members to danger (major advantage of group-living) Danger" is usually the presence of a predator. prairie dog meerkats

15 Alarm signals may have 2 fns: (i) alert group to beware (ii) alert the predator that it's been seen

16 Examples of alarm communication: a) Vocal -- vervet monkey alarm calls - eagle call causes members to look up - snake call causes members to look down. - leopard call causes group members to climb trees

17 b) Alarm Sound?? c) Alarm Visual Display

18 Alarm Calls: Mobbing Behavior in Birds Communication to the Community?

19 Different birds living in the same area have evolved very similar alarm calls why does this make sense?

20 II) COMMUNICATING LOCATION OF FOOD Represents cooperation -- found in social species. EXAMPLE: honeybees are a fascinating example. Aristotle documented that honeybees somehow recruit nest-mates to food sources.

21 Bees Finding Food Source Worker recruitment is happening!! Food Discovery Minutes

22 Round Dance Sequence 1) Starting point: Worker discovers a food source she feeds & then labels the flower with her scent. 2) Upon returning to the hive, she will communicate in a variety of ways with her sisters. If a food source has been discovered nearby, the discoverer will return & do a "round dance".

23 3) Round dances stimulate interest in the dancer -- an audience forms. 4) Audience smells flower odor begins search for that odor.

24 Waggle Dance Sequence * If food more distant, dancer does a "waggle dance". * More complex that the round dance. * Dance is a figure 8 -- waggling done in the straight section of the 8.

25 Both direction & distance is communicated --- how??? Distance communicated by number of waggles. Each waggle = about 25 m from the hive!!!

26 Review Osprey Food Communication Example -Osprey live in colonies -Hunt both schooling and solitary fishes -Display prey when returning to colony -Osprey view and assess display COMMUNICATION

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30 Yelling Ravens Communicate food location to other ravens Yet are doing it for selfish reasons!!??

31 Observation: Carcasses would have either 2 or fewer or 15 or more ravens why??

32 Explanation: Ravens are territorial & live in pairs - Territorial pairs will drive single transient birds away - If a transient finds a carcass, it yells to recruit other transients - Large groups of transients can t be intimidated by the territorial pair

33 Yelling raven communication about food location Appears to be altruistic transients helping other transients Actually, yellers are manipulative and selfish!!