Communication

Definition Action on the part of one organism that alters the probability pattern of behaviour of another organism in a way that may or may not be adaptive to both SignallerReceiver

Unintended receiver Signaller Information Decision and response

Communication Measurement Individuals A and B performs X 1 performs X 2 Communication occurs if: P(X 2 ) after X 1 ≠P(X 2 ) without X 1

Communication Measurement Units of communication - bit (binary digit) -amount of information required to control without error which of two equally probable responses will be chosen by the receiver

Communication Territorial bird - raises wings - intruder leaves - lowers wings - intruder advances Each presentation of the signal = one bit of information

Communication If H = number of bits If N = number of messages N = 2 H or H = log 2 N Amount of information in a signal Shannon-Weaver Index H(X) = - ∑ p i log 2 p i where p i is the probability of signal X i

Communication Kinds of signals 1. Graded -complex - signal varies with intensity

Communication Kinds of signals 1. Graded -complex - signal varies with intensity

Communication Kinds of signals 2. Fixed -simple - on/off signal

Communication Modalities 1. Chemical

Communication Modalities1. Chemical Advantages 1. Carry a long distance 2. Low energy investment

Communication Modalities1. Chemical Disadvantages 1. Depend on wind for dissemination 2. Difficult to track and locate sender 3. Long fade time - no complex signals

Communication Modalities1. Chemical Competing selective forces Volatile - low molecular weight Species specific - high molecular weight

Communication Modalities1. Chemical Competing selective forces - trade off Low MW High volatility Low distinctiveness High MW Low volatility High distinctiveness ABC Alarm calls Sexual attractants Territorial marks

Communication Modalities 2. Visual

Communication Modalities 2. Visual - Advantages a. Fast Transmission b. Sender is easy to locate c. Low energy (to send) d. Complex, rich signals a. Unpredictable habitat complexity b. Sender is easy to locate c. High risk of predation Disadvantages

Communication Modalities 3. Acoustic

Communication Modalities 3. Acoustic - Advantages a. Long range b. Fast transmission c. Not dependent on wind d. Use at night

Communication Modalities 3. Acoustic - Disadvantages a. High energy cost Time Body weight (% of initial) Starved crickets lose 5% per day

Communication Modalities 3. Acoustic - Disadvantages b. Easy to locate sender

Communication Modalities 3. Acoustic - Disadvantages c. confusion

Communication Modalities Acoustic - signal components need to be chosen carefully Frequency Amplitude e.g. - acoustic signals in shallow water Frequency 1 m

Communication Modalities Acoustic - signal components need to be chosen carefully Frequency e.g. - birds in forests transmissibility of signal Number of bird species

Communication Modalities 4. Tactile

Communication Modalities 4. Tactile - Advantages a.Need close contact b. Limited social use c. Low energy cost d. Locatible a.Very short range - low exploitation risk b. Fast transmission Disadvantages

Communication Modalities 4. Tactile - Examples Mating - Corixidae Grooming - chimps Feeding - gulls

Communication -Evolution of Signals-

Communication Signals - where do they come from? 1. Incomplete functional movements -intention movements - thwarted attacks

Communication Signals - where do they come from? 2. Completely formed but redirected acts - attacks on inanimate objects

Communication Signals - where do they come from? 3. Contextually irrelevant displays - gulls - in a territorial fight - revert to preening

Communication Signals - where do they come from? 4. Contextually correct and complete displays Sleeking and ruffling feathers in aggressive displays

Communication Signals - where do they come from? 4. Contextually correct and complete displays Conflict Muscular tensionHeat production Autonomic cooling response Decrease insulating effect of feathers Ruffling to allow heat to escape Sleeking to decrease thermal gradient Both are important as aggressive displays

Communication Ritualization An evolutionary process by which behaviour patterns become modified to serve as signals

Communication Ritualization

Communication Ritualization ? Grebe courtship

Selective forces in shaping signals 1.Identification and discrimination (= reduction of ambiguity) Identify signaller as 1.Individual 2.Member of a larger group

Selective forces in shaping signals 1.Identification and discrimination (= reduction of ambiguity) General trend - signals diverge or converge Factors resulting in divergence 1. Species specific sexual displays 2. Female choice in mating 3. Chance 4. Predator confusion

Selective forces in shaping signals 1.Identification and discrimination (= reduction of ambiguity) General trend - signals diverge or converge Factors resulting in convergence 1. Similar ecological pressures 2. Mimicry 3. Interspecific territoriality

Selective forces in shaping signals 2. Social complexity Complexity of social groupSignal complexity Number of signals

Selective forces in shaping signals 3. Compromise and allocation Bright colour - good for signal, not for concealment Yellow headed blackbird

Selective forces in shaping signals 3. Compromise and allocation normal short long Preferred by females -but too costly?

Percent response Selective forces in shaping signals 3. Compromise and allocation

Selective forces in shaping signals 4. Environmental constraints Prairie chicken courtshipRuffed grouse courtship

Selective forces in shaping signals 5. Sexual selection 6. Predation pressure 7. Intrasexual selection

Selective forces in shaping signals Summarize the effects of signalling and survivorship Signalling effort Survivorship Reproductive success Net reproductive success Optimum signalling effort

Selective forces in shaping signals SignallerReceiver Illegitimate signaller (Mimic) Illegitimate receiver (Predator) Functional system Exploitive system

Evolution of Signal Systems Empididae - Balloon flies -most derived form of courtship - male presents female an empty silk balloon - balloon indicates mate quality

Empididae - how did this signal come about? 1. Male predatory - doesn ’ t feed female 3. Male entangles prey in silk - feeds female Male predatory - feeds female 4. Male wraps prey in balloon- feeds female 5. Complex balloon, small prey- no feeding 6. Complex balloon, minute prey- no feeding 7. Complex balloon, no prey

Misinformation Do animals always communicate the “ truth ” ? Mimicry Batesian Müllerian

Misinformation Do animals always communicate the “ truth ” ? Camouflage

Misinformation How big a lie can you tell? -generally small lies are better than big ones X X is the model for a mimic Variation in X Y Y is the mimicking animal If ‘ Y ’ changes randomly r 1 - a small change ≈ 50% chance of being closer to X r1r1 r 1 - a large change << 50% chance of being closer to X r2r2

Misinformation How big a lie can you tell? -there is an effect of receiver experience Experience Benefits Plausibility little lie big lie