PBSI 311 Test 2 Exam

Communication

Transmission of information (a signal) from one animal to another, critical to social behavior and co-evolution between sending animal and receiving animal

Signal

Animal product evolved to carry specific meaning to others (can also include external attributes, actions, chemical compounds, energetic outputs)

Structural signals

may be continuous, ex: color marking on a male Canyon Wren

Behavioral Signals

Produced at certain times, ex: birdsong when the bird wants to be heard

Value of Communication

Signaling to potential mates, signaling from parents to offspring, signaling to group members: status, need for care, desire to play, alarm calls, food, shelter

Shared vs. Different Interest calls

In the case of shared interest, signals are expected to be honest vs. in cases of different interests signals might evolve toward dishonesty

Ultimate causes: Evolution

Ability to locate energy sources is strongly favored by natural selection, efficient receptors for signals + ability to gain information from signals caused evolution of communication

Signal Sender

has a structure that either is the signal (peacock’s tail) or makes the signal (vocal cords, scent glands, electric organs)

Signal Receiver

has receptors that transduce the signal into nerve impulses processed by the nervous system

Autocommunicaton

Communication with the self, occurs with echolocation and territorial/trail markers for orientation (ant might leave pheromone trail for itself)

Public Information/Eavesdropping

Signals have intended targets/recipients but once a signal is broadcast it becomes public information and is vulnerable to eavesdropping, (ex: female cowbirds prefer male calls that have already elicited chattering from other females)

Signaling Principles: Co-Option

Evolutionary adoption of something for new communication

Signaling Principles: Ritualization

Evolutionary refinement of a signal to be more efficient and accurate, benefits both sender and receiver

Signaling Principles: Stereotypy

Evolutionary reduction in the variation of a signal to minimize the uncertainty of meaning and potential overlap with other signals

Signaling Principles: Redundancy

Use of multiple signals with the same meaning to reinforce message and further minimize uncertainty, (ex: dogs mark territory with urine odors and visual scratch marks on the ground)

Audible Signals (Pros and Cons)

Effective in the dark, not impeded by obstacles, does not linger in environment, distance depends on medium and type of sound, production tends to be energy intensive

Sound

Vibration, sound waves have frequency (pitch or tone) and amplitude (volume, intensity, or loudness), species differ in their ability to hear ranges of frequences

Sound Production

Every 10 decibels of volume difference corresponds to a 10-fold increase in intensity (energy) and requires 10-fold more energy to create

Sound Perception

Humans perceive the intensity as only double with 10 dB increase, perceived loudness is affected by frequency and pressure, can be costly in terms of energy to create louder perceived sounds

Sound Features

Dissipation is the loss of intensity as sound travels, sound energy decreases exponentially over distance, sound loss also occurs due to absorption and scattering by the medium

Sound production: Tymbal

1. Vibrating a drum-like membrane (tymbal), produces mate attraction calls, moved by muscles

Sound production: Stridulatory Organ

1. Stridulating with a file and scraper (stridulatory organ), grasshoppers make a whirring or chirp sound

Sound Production: Larynx/Syrinx

Vibrating a membrane in an air flow, larynx (frogs, toads, mammals) or syrinx (birds) has a membrane that vibrates as air from lungs is pushed past, frequency changes with rate of vibration regulated by muscles that change tightness of membrane

Sound Production: Hitting

Hitting a substrate, beavers slapping their tails on the water when alarmed, woodpeckers knocking on trees

Sound Regulation: Pitch and Amplitude

For tymbal, stridulatory organ, or larynx/syrinx, animal can modulate pitch and amplitude (by changing amount of energy used)

Adaptations for amplifying sound

1. Resonant structure- typically hollow, external is a a hollow environment meant to amplify sound, internal is a hollow structure within the body

2. Vocal sacs- organs used to force larger volumes of air through the larynx, amplifies sound and allow increased duration
   
   

Sound Production: Cats and Dogs

Playful sounds tend to have higher frequency, aggressive sounds lower frequency, dogs recognize this and use pitch as an emotional cue, cats tend to use a higher-frequency purr when wanting to be fed

Roaring cats (lions, tigers, leopards, jaguars)

Flexible hyoid bone and a specialized ligament that allows them to roar (low frequency)

Meowing/purring cats (domestic breeds, cougars, cheetahs)

Rigid hyoid bone that allows for high-frequency vibration of a purr and the ability to meow

Infrasound

(<20 Hz) features: travels well through ground/water, receivers need to be large (ex: elephants, humpback whales)

Ultrasonic

(>20,000 Hz) features: little energy, dissipates rapidly with distance, receivers need to be small (high frequency), hearing membrane needs to be thinner, more likely to reflect

Ultrasound for Social communication and Echolocation

Social: Bats, rats, mice and some moths use ultrasounds with mates (rodent pups use ultrasound to call to mother)

Choruses

When many frogs or insects seem to sing synchronously (often on summer nights), singing in chorus to compete with other males, female is receptive to the leading singer

Auditory Noise

Animals cope with noise by receiving signals in a limited frequency range, signaling only certain points of the day, using neural processes that filter meaningful signals from the background noise, anthropogenic noise affects communication in birds, bats, and ocean animals

Chemoreception

Sensation based on chemicals binding to sensory receptors, includes smell and taste, body odors, pheromones, allomones, works well in dark environments, not impeded by obstacles, may linger/travel distances

Olfactory Discrimination

Interference of pheromone signals may come from similar species in same environment, mating signals are commonly a mixture of pheromones to make the message certain (extends across species)

Scent Marking in Dogs

Distributes scents by urinating small amounts on objects in their home range by lifting one leg

Scent Marking in Cats

Concentrates urine spraying at the core of their territory (Inside house), cat urine smells stronger than dogs, prevention by castration of young males

Tactile Signals (touching)

Efficient when animals are close, do not require light or air currents, has important function in social communication for aggressive and affiliative interactions

Aggressive Interactions

Direct physical force is the most threatening form of communication, including bites, slashes, kicks

Affiliative Interactions

In social groups, touch can be used to provide information about food, predators, and environment (Mutual grooming in mammals, birds, social insects), evolutionary forces driving removal of parasites

Vibrational Signals

Many animals gather vibrational information via a membrane, mostly found in invertebrates, (ex: some spiders use web vibrations to gain attention of potential mate, wolf spiders drum the ground as courtship signal), ex: treefrogs vibrate perches as an act of aggression, termites communicate danger by headbanging)

Visual Signals

Work well in light and absence of objects, travels fast, can be fairly inexpensive to produce, faces challenges by absorption of light by water and particles in it, absorption of red/orange/yellow wavelengths, refraction of light at air/water

Visual Signal Categories: Colors and Patterns

Alone or combined on the surface of an animal (ex: coral reef fish)

Visual Signal Categories: Movement

Body Language (ex: fiddler crab waving its large claw, peacock spreading tail)

Visual Signal Categories: Light Production

Used to attract mates, illuminate, or lure in prey (ex: Fireflies and anglerfish)

Visual Signals of Color: Pigment

Chemical compounds that absorb and reflect light, regardless of angle (white, yellow, red, orange, brown, black)

Visual Signals of Color: Structural

Physical microstructures that interfere/diffract/scatter light depending on angle (Creates blues, greens, metallics, iridescence) blues mostly common in birds, includes butterfly wings, blue iris, blue sky

Visual Signals of Color: Fluorescence

Involves pigment AND structure, light is absorbed by a pigment and then retransmitted at different wavelength, provides color in some coral reef fish, scorpions

Visual Signals: Movement/Body Language

Visual communication, includes posture, muscle tension, tail movement, ear position, conveys messages like fear, aggression, playfulness, submission

Visual Signals: Light production

Bioluminescence, used to help avoid predators by unique ability to send and receive red wavelengths

Visual Noise

Can obscure a signal, signals divergence to stand out from background, camouflage uses visual noise to blend in

Electrical Signals

Works well in murky water, used predominantly by fish swimming in muddy water, can be used for navigation as well

Strongly Electric fish

Use electricity mostly for predation and defense

Weakly electric fish

Use electricity for communication and location

MultiModal Signaling

Uses more than one mode to convey its message, (e.g. Cordon bleu generates multimodal courtship signal by males and females singing, bobbing heads, dancing rapidly to produce vibrations), honeybee dance language

S*xual Selection

Preference by one s*x for certain traits leads to a type of natural selection, for signals used to attract mates benefit is a direct impact on fitness, mate choice has a strong effect on signaling

Runaway S*xual Selection

When one s*x (generally female) prefers mate to have a strong signal, selection will favor making that signal bigger, longer, or stronger (beyond what is necessary for the signal or message), thus animals often display bright colors, huge horns/antlers

Runaway S*xual Selection: Supernormal Stimuli

Runaway s*xual selection may be related to animal’s increased attraction to supernormal stimulus- an exaggerated version of natural stimulus (e.g. a gull will react more to an oversized egg even though it can’t possibly be its own)

Runaway S*xual Selection: Peacock’s tail

A peacock’s tail is important in mate choice, especially the eyespots, males assume a 45 degree angle to the right arc of the sun, maximizing the blue-green color seen by peahens

Deceitful (Dishonest) Signaling

Evolved to mislead, if a deceitful signal favors survival and reproduction, the genes will spread. in offspring young will exaggerate their actual needs to get more care, in mating sneaking males lurk near other males producing loud mating signals

Handicap Principle

A signal is honest if it is costly to produce, the cost acts as a handicap, ensuring that only fit individuals can display honest signals, discourages cheating

Interspecies Deceit: Mimicry

Eye-like patterns on butterflies and moths to scare off predators, fireflies mimicking light flashes of other species to prey on them, spiders mimicking moth pheromones, ants mimicking pheromones of another group to be accepted

Interspecies Deceit: False Signaling

Kildeer performing a “broken wing act” to lure a predator away from its nest

Evolution of Deceitful vs. Honest Signaling

Interacting animals generally act in their own best interest and communicate to enhance fitness (whether honest or deceitful)

Evolution of Deceitful vs. Honest Signaling: Sender

Communication evolves to gives messages that benefit the sender, minimize the cost or effort of signal

Evolution of Deceitful vs. Honest Signaling: Receiver

Communication evolves to enhance the information obtained (benefit) from a signal, discriminate honest from deceitful signals

Game Theory

Uses mathematical or logical models to predict how interacting animals should behave and whether they should cooperate (e.g. Prisoner’s dilemma), communication provides a strategic interaction for the “game” in which signalers and receivers each have goals, costs, and benefits (that can be determined by evolution rather than cognition), multiple strategies can coexist in population

Interspecific Signaling: Attractive signals

Can be used to lure in another species as prey (deceit)

Interspecific Signaling: Repellant/defensive signals

Distinct sound (rattlesnake), color (red), patterns (stripes). sender and receiver avoid risk

Interspecific Signaling: Inadvertent signals

Those that are eavesdropped

Interspecific Signaling: Mutual Relationships

Attractive signals can be used for mutual interspecies relationships too, cleaner fish eat parasites and dead skin from larger fish, cleaner fish signal they are non-prey with patterns/colors and movements (dances) that help them stand out, client fish signal willingness to be cleaned

Interspecific Signaling: Pets

Domesticated animals have evolved interspecific signaling, dogs show facial expressions (eyebrow movements) not seen in wolves and can follow human gazes, adult cats rarely meow to each other meowing is primarily used to communicate with humans

Random Movement

Might accomplish goal of finding food or shelter

Directional Movement

Oriented based on input; used in most forms of shelter

Orientation

Occurs at all spatial scales, which direction should the animal move? Many animals use environmental cues: landmarks, compass cues, some animals use memory and experience from previous movements

Navigation

Used mainly at intermediate/broader spatial scales, how does the animal reach a specific destination?, often involves external cues to set direction of movement (Like the sun), internal calculation of distance and direction

Simple Orientation

Habitat preference based on simple information (Cockroach preferring dark environments)

Complex Orientation

Habitat preference based on complex information (herbivorous insects finding host plant), may be determined genetically (using odor to locate ideal plant), may be learned (caterpillars imprinting plant preference by feeding as larvae)

Navigation: Genetics

Navigation can be shaped by evolution (genetics), works if the same location or same migratory route is used across generations (e.g. sea turtle migration)

Navigation: Learning

Works for environments that are unpredictable or changeable, (e.g. homing in pigeons, squirrels genetically programmed to build nest, but nest location is based on preference and current circumstances)

Triangulation

Measuring the intensity of the stimulus from two different locations in some combination of time and/or space

Simultaneous Triangulation vs. Sequential Triangulation

Simultaneous: compare across distance, e.g. using two sensory organs and simultaneous difference in perception to calculate distance/direction Sequential: compare across time (after moving), e.g. moving head back and forth

Vision triangulation (Depth perception, stereopsis, or binocular stereopsis)

Using binocular disparity, the difference in positions in the left and right eye images, important for predators, thus predators have forward directed eyes with highly overlapping visual fields, many animals combine simultaneous triangulation + sequential triangulation to maximize accuracy

Auditory Triangulation

Bats and owls uses interaural intensity and time differences (loudness and timing in each ear)

Sequential odor triangulation

Walking and flying insects generally move upward when they detect an odor, compare concentrations across time, and change their movements if they encounter lower concentration

Simultaneous Odor Triangulation

Dogs can triangulate using two nostrils (they combine this with sequential odor triangulation)

Perception of Magnetic fields

Animals may use external magnetic cues as a compass (orientation) or map (navigation), magnetic compass: some animals use magnetic information to determine compass direction, magnetic map: some animal use several geomagnetic parameters (inclination; intensity) that vary in space to create a true map of their location, still largely unknown

Kinesis (Movement Without Orientation)

The simplest locomotor response to the environment; change velocity or alter turning rate based on stimulus intensity, (e.g. move faster in a bright environment, stop in the dark), no orientation toward/away any stimulus just the presence or absence of movement based on current conditions

Taxis (Orientation: Directional based on stimuli)

Integration of orientation (directional response to stimulus) with kinesis (locomotor response to stimulus), moving toward light, odor, air current

Taxis: Example

Positive phototaxis- attraction to light

Negative anemotaxis- moving away from wind

Positive thigmotaxis- positive response to touch

Menotaxis- moving away at an angle relative to a stimulus rather than directly toward or away

Counterturning (Orientation: Directional based on stimuli)

Simple mechanisms to maintain overall direction of movement; each change in direction is balanced by movement in the opposite direction (e.g. counterturning in desert ant)

Landmarks (Orientation: Directional based on stimuli)

Can be used in orientation and include mountains, trees, rocks (e.g. a digger wasp flies several loops around the nest before leaving to learn the landmarks and ensure a correct return), mammals create olfactory landmarks by scent marking (dogs, cats, deer)

Learning the Landscape (Orientation: Directional based on stimuli)

Learning specific paths or sequences of landmarks (a broader landscape) through repeated experiences, NOT a full cognitive map (e.g. many young animals make exploratory trips from home to learn the landscape)

Landmark vs. Learning the Landscape

Displace landmarks within the landscape, if the animal goes to correct location after landmarks are moved, it learned the spatial relationships between landmarks → learned the landscape, but if the animal goes to an incorrect location → landmarks

Snapshot Orientation (Orientation: Directional based on stimuli)

Using a stored “visual snapshot” of a scene to orient, animal will remember visual image of landscape, compares current landscape with library of snapshots to orient (bees, ants, wasps), view-based and not based on objects or sequence of objects

Landmark, Landscape, Snapshot Example: Finding your way back to a friend’s house

Landmark: “I turn left when I see the tall, red statue)

Landscape Learning: “First right, then second left, then follow the curve)
Snapshot: “This looks right- the way the trees frame the road and the shape of the yard”