Communication

II. Sensory modalities

A. Types used for signal production or reception

1. Mechanosensors

a. Hearing
b. Touch
c. Equilibrium

2. Photoreception: vision
3. Chemoreception: olfaction

4. Electroreception: electric fish, some sharks and rays

B. Other sensory modalities

1. Thermoreception

2. Magnetoreception

C. Modality influences signal transmission properties.

D. Expect animals to optimize signal design to maximize signal-to-noise ratio

1. Sound transmission

a. Expect frequencies used to avoid background noise

b. Expect frequencies to minimize degradation from environment

i. High frequencies attenuate rapidly, reflect from obstacles, e.g. bats and dolphins use ultrasound to "see" their world by echolocation

ii. Low frequencies can pass around obstacles, e.g. elephants use infrasound which can travel for miles

2. Birds produce sounds and hear best at the frequencies of lowest noise

3. An association between frequency and habitat provides evidence for optimal signal design

III. Possible outcomes

A. Mutual benefits - occur when sender and receiver share common interests
B. Eavesdropping - when an unintended receiver exploits a signal

1. Tungara frog females like chucks, but so do fringe-lipped bats!

C. Manipulation - when a sender sends a false signal

1. Predator-prey examples, e.g. fireflies
2. Alarm calls

IV. Signal function

A. Mate attraction, territory advertisement - honest advertisement

B. Alarm calls - predator detection

C. Recognition

1. Individual - distinctive signals occur where offspring identification is difficult, e.g. colonial swallows, free-tailed bats

2. Kinship

i. inbreeding avoidance - dissassortative mating by MHC in mice and humans
ii. care-giving - communal nesting by MHC in mice