Animal communication

Mechanism, function, ontogeny, phylogeny

Tinbergen’s four questions

proximate cause

Mechanism that caused a reaction

Ultimate cause

The function that allows an animal to respond

Non-constancy

Communication signals have a clear start and endpoint

Specialization

Adaptions for signal production, transmission, or reception

Interactional

Intention to attack, escape, initiate courtship or mating; care-giving, attentiveness

Identity

Species ______; individual ______; neighbor; sex of signaler; maturity/age class; breeding state

Ethology

Study of animal behavior. Developmental and evolutionary origins of behavior

Communication

Is an action by one organism that alters the behavior of another organism that is adaptive to either one or both participants

Non-constancy

Communication signals have a clear start and endpoint

Specialization

Adaptations for signal production, transmission, or reception

Internal processing

Signals must be picked up and interpreted by the receiver

Natural selection

Variation exists in behavior and structure. Some of that variation is heritable. Certain inherited traits make it easier for an animal to survive and give that trait to offspring

Ethology

Is an evolutionary approach to the study of animal behavior

Honey bee waggle dance

Bees communicate information about the location and quality of food sources outside of visual range

Search image

A hypothetical mental picture of a prey item used by a predator to search specifically for a cryptic, common, edible prey

Sign stimulus

The component of an action or object that triggers a fixed response in an animal

Releaser

A sign stimulus given by one animal to another as a social signal

Fixed action pattern

Innate, stereotyped response triggered by a well-defined simple stimulus. Once activated, the response is always performed to completion

Imprinting

Form of learning in which individuals exposed to certain key stimuli, usually during an early stage of development, form an association with the object and may later show sexual behavior toward similar objects

Critical period for learning

A period in the life span of an individual where learning or imprinting is greatly facilitated

Instinct

A behavior pattern that reliably develops in individuals that receive adequate nutrition, and that is given in functional form on its first performance

Handicap hypothesis

Some signals, like the peacock’s tail, are costly to produce. Since they are costly they are more likely to be reliable

Intention movements

Communication signals that originate from movements made when the animal is getting ready to perform a particular behavior

Displacement behavior

Animals engage in “irrelevant” activities when they experience conflict

Ritualization

Revolutionary process that transforms an incidental cue/behavior pattern into a true communication signal

Principle of antithesis

States that signals with opposite messages tend to be opposite in form

Code breaking

Behavior that mimics the triggering component of a fixed action pattern to exploit its benefits

Altruism

Is any form of behavior that provides a benefit for another individual at a cost to the individual performing the action

Reciprocal altruism

Sacrifices made by one individual that benefit another individual that is later reciprocated, so that both gain in the long run. Requires that the two individuals recognize each other as individuals

Kin selection

Is the process that leads to changes in gene frequencies in the population as a result of reciprocal, mutually beneficial actions among related individuals

Fitness

The more fit an individual is, the higher his or her chances of surviving and propagating his or her genetic blueprint

Individual lifetime fitness

Reproductive output; product of the animal’s lifespan and number of offspring produced

Inclusive fitness

Is calculated from the frequencies of gene survival among a group of genetically related individuals

Group selection

The group, rather than the individual, is the unit of selection

Goal of sensory analysis

To pick up information about environmental events and objects in order to categorize them as edible, dangerous, interesting, or irrelevant

Transverse wave

Particle displacement is perpendicular to direction of wave propagation

Longitudinal wave

Particle displacement is parallel to direction of wage propagation

Frequency

Measured cycles per second or hertz. Indicates the number of cycles each wave makes in one second. The more cycles per second, the higher the pitch we heat

Intensity

Measured in decibels. The higher ______ of a sound, the louder it sounds

Attenuation

Decline in signal intensity due to absorption, scattering, distance from source; particularly high frequencies

Echoes

Are produced when sounds are reflected from an obstacle and follow an indirect path to the ear of the receiver

Longer wavelengths

Low frequency sound have ______ than high frequency sounds and can vent around obstacles

Monopole

Sound alternately contracts and expands in concentric circles around source

Dipole

Sound source that vibrates back and forth

Tymbal

Most complex insect sound-producing mechanism known. Circular membrane surrounded by heavy rings on cicada’s abdomen. Contraction of muscle causes it to spring back, producing a loud click or pulse. Amplified by resonating cavity in the abdomen

Specializations of the sender

Modifications of body structures for purposes of transmitting signals

Adaptation to the channel

Modifications that facilitate the transmission of signals through a communication channel

Specializations of the receiver

Modifications of sensory and neural systems that facilitate signal reception

Hemispherically

Sound spreads ________

Waveform

The _____ of a sound is a representation of sound pressure versus time

Amplitude spectrum

______ or a sound is a representation of amplitude by frequency

Periodic

Tonal, repeating pattern in the waveform

Aperiodic

Noise with no repeating pattern

Larynx

Main source of sound production by mammals. Controls airflow during breathing and sound production

Source

During normal speech the vocal folds vibrate at a frequency that depends on their length and mass as well as the amount of tension in the muscles that control them

Filter

The vocal tract is a complex resonant _____ system that amplifies certain frequencies and attenuates others

fundamental frequency

Lowest frequency component in voiced speech sounds, linked to vocal fold vibration

Formants

Resonances in the vocal tract

Because sound travels faster in a helium mixture

Why does your voice become higher pitched after inhaling helium?

Syrinx

Found in birds. Located at the base of the trachea where the two bronchial tubes converge. Contains two separate oscillating membranes that allow generation of two different sound sources

Stridulation

Sharp blade is rubbed against a row of small teeth

Absorption

Loss of energy due to contact with medium, which may convert signal’s energy into another form

Diffraction

Redirection of the signal because of contact with an absorbing or reflecting medium

Geometric spreading

Signals radiate in several directions from the source; not perfectly directional; result = energy loss

Interference

Signals reflected from the substrate later interact with the originally transmitted signal

Reflection

Signal bounces back in the direction of the emitting structure as a result of striking a reflective medium

Refraction

Signal direction/speed is altered/perturbed by medium or climatic changes like temperature gradients

Reverberation

Multiple scattering events produce a time delay in the arrival of the signal, perceived as an echo; blurring

Scattering

Signal contacts an obstruction and undergoes a complex multidirectional change in the transmission direction

Phase

Onset position

Spectrum

_____ of a sound is a representation based on a mathematical analysis of the waveform

Sine wave

Simplest sound type.

Period: 1 repetition

Amplitude: displacement of pressure wave

Phase: relative position; 360 degrees per cycle

Complex sounds

Most sounds in nature

Particle detector

Row of hairs on antenna or abdomen of insects. Selective to species-specific frequency range

Pressure detector

Membrane stretched over a closed cavity; vibrates in response to sound pressure fluctuations

Place theory of hearing

Cochlear fibers vary in length

Tuned to vibrate at specific frequencies

Different positions along the cochlea respond selectively to different frequencies to determine what pitch is w hear

Action potentials

The inner ear converts the mechanical vibrations into a sequence of electrical signals called _________

Tonotopic map of frequency

Different positions along the cochlea respond selectively to different frequencies

Action potentials

Are generated in the auditory nerve and propagated to the central nervous system

Temporal coding

Information is coded in the temporal synchronization of nerve spikes

Phonotaxis

Orientation toward sound

Medial and lateral labia

Bird sound is produced when air passes through the ___________ on each side of the syrinx.

Bilaterally

Sound is produced _______ except when air is prevented from flowing through one side of the syrinx

Sound shadow effect

At high frequencies, wavelengths are very short, and an animal’s head will partially block the sound waves

Interaural intensity difference

When a sound comes from a source located to one side of an animal’s head, the difference in intensity between the two ears helps to localize the sound source

Interaural time difference

There is a slight delay in the time of arrival of the sound at the opposite ear that also helps sound localization

Mobbing calls

Are repeated, loud calls that attract others. Unlike alarm calls, mobbing calls consist of a repeated series of loud calls, wide range of frequencies, and sudden sharp onset and offsets

Alarm calls

In birds causes others to seek cover. Alarm calls in different bird species have similar structure. Single, brief call. Low amplitude. High frequency. Gradual onset.

Narrowband sounds

Are harder to localize than broadband sounds

High frequencies

Are linked to fear rather than attack

Adaptation hypothesis

Any given sound in the repertoire of a species has been favored by natural selection because it’s influence of the because of other animals is beneficial to the sender and/or his or her close relatives

Gradual onsets and offsets

Sounds with a narrow band of frequencies and ____________ are hard to localize

Brightness

Intensity

Hue

Dominant wavelength or frequency

Chroma

Degree of saturation or purity of the dominant frequency

Trichromatic color vision

Human color vision depends on interactions of three types of come cells in the retina of the eye, each sensitive to a range of wavelengths or light

retinal

Cone cells in the retina contain a pigment derived from a protein linked to a small molecule called ______. The pigment by absorbs light energy which activates ____ neurons, generating action potentials in the optic nerve

Tetrachromatic color vision

Four types of cone cells. Allow birds, lizards, turtles, and many fish to distinguish colors in the near ultraviolet range of the spectrum

Dichromatic color vision

Two types of cone cells. Most animals