Chap.06 Evolution and Ecology 鄭先祐 (Ayo) 教授 國立台南大學 環境與生態學院 生態科學與技術學系 環境生態研究所 + 生態旅遊研究所.
溝通:管道與功能 (Communication: Channels and Functions) -- 動物行為學 (Ethology)...
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Transcript of 溝通:管道與功能 (Communication: Channels and Functions) -- 動物行為學 (Ethology)...
溝通:管道與功能 (Communication: Channels and Functions) -- 動物行為學 (Ethology)
鄭先祐 (Ayo)
國立 臺南大學 環境與生態學院生態科學與技術學系 教授
Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/
大學部 生態學與保育生物學學程 ( 必選 ) 2010 年 秋冬
Ayo 教材 (動物行為學 2010) 2
Part 3. 個體間的互動
生殖行為 (Reproductive Behavior) 親代照顧與交配體系 (Parental Care and Mating
Systems) 溝通:管道與功能 (Communication: Channels and
Functions) 溝通的演化 (The Evolution of Communication) 衝突 (Conflict) 團體生活,利他和合作 (Group Living, Altruism,
and Cooperation)
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15a 溝通:管道和功能
The definition of Communication channels Vision Audition Substrate vibration Chemical senses Touch Electrical fields
Multimodal communication function Species recognition Mate attraction Courtship and mating Maintaining social bonds Alarm Aggregation Agonistic encounters Communication about resources: a case study
Communication: Channels and Functions
By Goodenough, McGuire, and Jakob
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Important messages are sometimes whispered
When male Asian corn borer moths are close to a female, they Rub specialized scales on their forewings against their
thorax Produce extremely low intensity ultrasonic courtship songs
Courtship songs suppress escape behavior of the female and facilitate mating The quiet song lowers the risks of eavesdropping ( 偷聽的
風險 ) by rival males and predators
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Defining communication
Communication occurs when a sender produces a signal that contains information And is detected by a receiver who interprets the signal
and decides how to respond But sometimes an animal is not intended to receive a
message i.e. an owl hears the noises from a mouse Cue: provides information to another animal but does
not benefit the sender
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Animals must benefit from a signal
The sender benefits from the transmission by altering the behavior of the receiver Signal: a courtship dance, song, feather crest Display: a stereotyped sequence of behaviors that has a
signaling function On average, receivers must benefit from paying
attention to a particular signal But receivers do not always benefit Sometimes senders manipulate receivers by sending
dishonest signals
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Channels for communication
Feature Visual Auditory Chemical Tactile Electrical
Effective distance
Med Long Long Short Short
Localization of sender
High Med Var High High
Go around obstacles
Poor Good Good Poor Good
Speed of transmission
Fast Fast Slow Fast Fast
Complexity High High Low Med Low
Duration Var Low High Low Low
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Properties of visual signals
Ease of localization: the location of the sender is known The receiver can see and, therefore, respond
Rapid transmission and fade-out time As soon as the sender stops displaying the signal is gone
Visual systems provide a rich variety of signals Brightness, color, spatial and temporal patterns, movement
and posturing But, if the sender cannot be seen, its signals are useless
Vision is easily blocked They are hard to see during nighttime or in dark places The size of visual signals decreases with distance
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Environmental conditions affect visual stimuli
During agonistic displays, shark species strongly depress both pectoral fins and hold them down
Sharks in clear water have conspicuous markings on their pectoral fins Black or white tips and margins enhance the visibility of
this postural display Sharks living in habitats where light is scarce only use
the posture
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In many sharks, agonistic displays involve symmetrical depression of the pectoral fins ( 胸鰭 ).
(a) a Galapagos shark using this visual signal of agitation. (b) Blacktip reef shark have markings on their pectoral fins that may
enhance the agonistic display.
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Use of visual signals in territorial communication
If a roving razorback sucker fish approaches a territorial male The territorial male rolls his eyes, exposing the whites
of his eyes The interloper ( 闖入者 ) retreats
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Species use visual signals
At night or in dark places Nocturnal species that cannot produce light use visual
signals Are most active at dawn and dusk, when light is available
Colors are difficult to distinguish so visual signals focus on contrast and involve white Eagle owls have white feathers on their throat Visible when the throat is inflated and deflated during
vocal displays
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Although eagle owls are nocturnal, they use visual signals at dawn and dusk when some light is available.
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The size of visual signals
Conspicuousness of visual signals diminishes with distance
Animals adjust their visual signals with respect to receiver distance
Courting male fiddler crabs broadcast their courtship displays if a receiver (female conspecific) is absent
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(a) stages in the claw-waving display of male uca perplexa. (b) the interval between claw waves, (c) the duration of claw waves
As distance decreases, the interval and duration between claw waves decreases
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(d) the horizontal sweep of the claw tip decrease with decreasing receiver distance.
Thus, as distance to receiver decreases, male displays increase in intensity but become less conspicuous.
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Properties of auditory signals
They can be transmitted over long distances Especially in water
A rapid means of sending a message Particularly at close range
Conveys a message when there is limited visibility Night, deep water, dense vegetation
Sound signals can be complex Temporal variation of frequency (pitch) and amplitude
(loudness)
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Animals produce a variety of sounds
Sounds are generated by structures that have evolved in association with respiratory structures Mammals have a larynx Birds have a syrinx that produces complex sounds
Sounds are generated by striking objects Rabbits and deer signal by foot stamping Beavers slap( 拍打 ) the water Woodpeckers drum on trees
Sounds are generated by rubbing appendages together Insects rub parts of their exoskeleton together
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Sound production: stridulation ( 唧唧鳴聲 )
Stridulation: sound production by rubbing body parts together Cricket wings have a thickened edge scraper that rubs
against a row of ridges (the file) Is not confined to insects
A male club-winged manakin creates sound by moving his wings and highly modified secondary feathers
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A male club-winged manakin creates sound by moving his wings and highly modified secondary feathers
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Some animals make sounds that humans cannot hear
Ultrasounds: sound frequencies are above those audible to humans Cetaceans, bats, rodents and other animals produce
and detect ultrasounds as part of echolocation Male and female concave-eared torrent frog calls have
audible and ultrasonic components Males approach calling females (positive phonotaxis) Species can avoid the masking effects of the low-
frequency background noise of streams and waterfalls
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concave-eared torrent frog 凹耳蛙(學名: Amolops tormotus )為蛙科湍蛙屬的兩棲動物,是中國的特有物種。分布於浙江安吉縣和建德市以及安徽黃山,一般棲息于山溪附近。其生存的海拔範圍為 380 至 700米。該物種的模式產地在安徽黃山。
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Infrasound
Humans cannot hear frequencies below 20 Hz (infrasound) Most elephant calls are infrasonic
Infrasonic calls have the same source as audible calls Air driven from the lungs moves the larynx
Elephants are social animals that live in matrilineal family groups Daughters remain with mothers Sons live in bachelor groups Long distance communication between family members
and groups is critical
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Infrasound works well for long distance communication Low frequency sounds are less degraded
Through refraction (bending of sound waves as they pass from one medium to another of different density)
Reflection (the bouncing off of a new medium) Absorption (the conversion of sound energy to heat)
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Substrate vibration
Animals can communicate by seismic signals encoded in the pattern of vibrations of the environment The ground or water surface Produced through percussion on the substrate
Kangaroo rats ( 更格盧鼠 ) declare territory ownership through foot drumming
Blind mole rats bang their heads against the burrow ceiling
Water striders use vibrational signals for sex identification, mate attraction, courtship, and territorial defense
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Elephants monitor airborne and ground signals
Elephants distinguish subtle differences between seismic calls To discriminate between alarm calls of familiar and
unfamiliar conspecifics Elephants detect seismic signals through two pathways
Bone conduction: through the feet, front legs to the shoulders, and to the middle ear
Mechanoreceptors in the skin of the trunk and feet Elephants monitor ground-borne and air-borne signals to
determine the distance of the vocalizing individual
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Properties of chemical signals
Smell and taste are another channel for communication
Based on the movement of odor molecules from signaler to receiver
Information may be carried by chemicals over long distances By currents of air or water
Rates of transmission and fade-out time are slower than for visual or auditory signals
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Chemical signals are durable ( 耐久的 )
They remain after the signaler has gone Delineation ( 描繪 ) of territorial boundaries
Some mammals increase the signal life of chemicals Secreting them with oily carrier substances or urinary
proteins Do not require continued energy expenditure by the
sender Used where visibility is limited It is more difficult to locate a signaler using chemicals
than visual or auditory signals
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Signals are complex blends of chemicals
The proportions of different chemicals produce their effects Effects are produced by the full chemical “image” of the
signal (the “odor mosaic”) Scent marking: the act of strategically placing a
chemical mark in the environment Female marmosets ( 狨猴 ) discriminate familiar from
unfamiliar conspecifics Each female has a unique scent signature (odor mosaic)
based on the ratios of chemicals in the scent mark
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marmosets ( 狨猴 ) Common marmosets deposit
scent marks that are complex combination of many chemicals.
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A signal’s meaning varies
With the context in which it is given As worker bees groom a queen honeybee they pick up a
chemical signal And distribute it throughout the hive The chemical prevents the rearing of any additional queens
The queen also exudes this chemical on her nuptial flight Causing males to gather around her
This same chemical serves as a queen inhibitor or as a sex attractant Depending on the context
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Detection of chemical cues may occur at a distance Remote chemoreception: airborne chemical cues Contact chemoreception: chemical cues are detected
through direct contact with the chemical signal One ant touches another ant’s body to evaluate
chemicals on the other ant’s body To determine if the individual is a colony member or an
intruder Contact chemoreception is associated with nonvolatile
chemical cues
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Some animals have organs for chemical communication
Amphibians, reptiles, and mammals may have a vomeronasal (Jacobson’s) organ For communication between mates, parents and offspring,
and rivals Its neural wiring does not go to the main olfactory system
It is located in the roof of the mouth or between the nasal cavity and the mouth
Communicative chemicals reach it through the nose, mouth, or both
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The flehmen response
Chemicals are nonvolatile and must be brought to the organ In a snake, the chemicals are delivered by the tongue
A mammal licks or touches its nose to the chemicals and make a facial grimace( 怪相 ) (flehmen) To transfer the chemicals to the organ
The flehmen response (from German flehmen, meaning to curl the upper lip), is a particular type of curling of the upper lip in ungulates, felids, and many other mammals, which facilitates the transfer of pheromones and other scents into the vomeronasal organ, also called the Jacobson's Organ.
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Flehmen is a characteristic posture in which the head is raised and upper lip is curled back. It serves to deliver nonvolatile communicatory chemicals, such as those found in urine or glandular secretions, to the vomeronasal organ.
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Pheromones ( 費洛蒙 )
Chemicals produced to convey information to other members of the same species
Releaser pheromones have an immediate effect on the recipient’s behavior A female silk moth emits a minuscule amount of her
powerful sex attractant bombykol Males immediately turn and fly upwind to find her
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Releaser pheromones
Trail pheromones in insects direct the foraging efforts of others Alarm substances in insects warn others of danger
Lactating rabbits produce mammary pheromone Which stimulates their pups to search for and grasp onto
a nipple
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Primer pheromones
Exert their effect more slowly By altering the physiology and behavior of the recipient
A queen honeybee produces pheromones that keep her as the only reproductive individual in the colony Prevents workers from feeding larvae the special diet
that would cause them to develop into rival queens When the queen dies the inhibiting substance is no
longer produced and new queens can be reared
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Vertebrates produce primer pheromones
So reproduction occurs in the proper social or physical setting
Origin Recipient Effect
Female urine
Female Inhibits cycling and ovulation
Male urine Female Induces cycling and ovulation
Female urine
Male Prompts release of testosterone and luteinizing hormone
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The vomeronasal organ
There are no functional differences between the vomeronasal organ And the main olfactory system
The organ can be stimulated by substances other than pheromones A hunting snake responds to chemical cues of prey
brought to the organ by the flicking tongue Chemicals from prey species are not pheromones
(communication within a species) The behavior is foraging - not communication
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Pheromones can act via the olfactory system
Scent marks left by a female hamster prompt a male to locate her In a sexually inexperienced male, another component
of the vaginal secretion perceived through his vomeronasal organ prompts him to investigate and mount her
Sexually experienced males have learned the odor cues of receptive females And no longer need the vomeronasal organ to stimulate
mounting
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Properties of tactile signals
Animals communicate by touch Tactile messages can be sent quickly It is easy to locate the sender, even in the dark It is effective over short distances but not around barriers
Honeybee scouts inform nest mates of the location of a food source by dancing Recruits follow the dancers’ movements by touching them
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Social grooming, a form of tactile communication that builds and maintains social bonds, is displayed by many mammals, including horses.
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A message sent by touch can be varied
By how the recipient is touched , rubbing ( 摩擦 ), patting( 輕拍 ), pinching ( 擰捏 ) Where the recipient is touched The frequency and duration of touching The extent of surface area touched
Humans send and decode tactile signals
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Electrical fields
Two distantly related groups of tropical freshwater fishes produce weak electrical signals used in orientation and communication Knifefishes of South America Elephant-nose fishes of Africa
Torpedo rays and electric eels generate very strong electric discharges to stun prey or predators
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Electrical signals
Are generated by electric organs derived from muscle Muscle cells are arranged in stacks Their currents are added to result in a
stronger current When an electric organ in weakly
electric fish discharges An electrical field is created around the
fish This field is the basis of the signal
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Creating diverse electrical signals
Different signals can be created by varying The shape of the electrical field The discharge frequency The timing patterns between signals Stopping the electrical discharge
Electroreceptors in the skin detect electric organ discharges
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Patterns of electric discharge in weakly electric fish
Wave-type pattern Produces signals continuously Waveform resembles a sine wave
Pulse-type patterns produce electricity at higher rates when active And at lower rates when resting The waveform has a complex multiphasic structure
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(b) Wave type: Some species of weakly electric fish produce electrical signals continuously with monophasic waveforms.
(c) Pulse type: Other species produce electrical signals in a pulse pattern, often with multiphasic waveforms. These so-called pulse-fish discharge at high rates when active and low rates when at rest.
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Sternopygus macrurus Eigenmannia virescens Apteronotus albifrons ( 線翎電鰻 )
Sternarchorhamphus macrostomus ( 胸鉤電鰻 )
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Rhamphichthys rostratus Gymnorhamphichthys
hypostomus Hypopygus lepturus ( 下
臀電鰻 )
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Properties of electrical signals
When an electric organ discharges An electrical field is created instantaneously It disappears the instant the discharge stops
They transmit information that fluctuates quickly i.e. aggressive tendencies
It does not propagate away from the sender But exists as an electrical field around the sender
Its waveform is not distorted during transmission So it is a reliable indicator of the sender’s identity
Waveforms are different between the sexes And among different species
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Electrical signals suit the environment
For communication in animals Active at night That live in muddy tropical rivers and streams That live at depths where visibility is poor
They can move around obstacles And are undisturbed by suspended matter
However, they are effective only over short distances Different weakly electric species may coexist in an
area So the short effective distance of the signal reduces
electrical “noise” when many individuals signal at once
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Electric signals send the same messages
That other animals send through other channels Males of some species advertise their sex and species
by electrical signals They also court females by “singing” an electrical
courtship song Signals are also used during agonistic encounters
Patterns of discharge are associated with aggression, dominance, and submission
Parents and offspring may communicate via electrical signals, to remain close to each other
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Multimodal communication
Multimodal communication: animal displays contain signals from two or more sensory modalities Signaling occurs simultaneously or sequentially
The courtship display of a male bird may simultaneously contain visual and auditory signals
Elephant vocalizations have seismic (ground borne) and auditory (airborne) components
Messages conveyed in different signaling channels can be Redundant: convey the same thing or Nonredundant: convey different things
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Multimodal messages in spider courtship
The courtship display of male brush-legged wolf spiders contains visual and seismic signals Visual component: the male raises and lowers his first
pair of legs Seismic( 震動 ) components: stridulation ( 唧唧鳴聲 ) ,
up and down bouncing of the body, and striking the substrate with mouthparts
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Benefits and costs of multimodal communication
Benefits for nonredundant multimodal signals More information can be sent per unit time Insurance that the message is received and recognized
Costs for signaling in multiple sensory modalities Requires more of the sender’s energy Recipients need more energy to receive and process multiple
signals May make senders and receivers more susceptible to
predation
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Functions of communication: species recognition
Conspecifics are competitors for food, shelter and mates But potential mates or members of a social group should be
wooed ( 求婚 ) It’s adaptive not to mistake heterospecifics for
conspecifics Don’t waste time and energy courting an animal with
whom it is impossible to produce viable offspring Don’t defend a territory from an individual that is not
competing for resources or mates
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All sensory channels are used for species recognition Birds use song frequency (which notes are sung) and
syntax ( 語法 ) (how the notes are strung together) Crickets rely on differences in song temporal patterns Insects use olfactory cues
Some species use species-specific pheromones to attract mates
Others rely on visual cues, such as displays or color patterns
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Selection for different species’ signals
Male frogs and toads attract their mates by calling at night
A female must choose one of her own kind from the variety of callers at the local pond Who is the strongest?
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Animals can fail to distinguish conspecifics
Males of many species indiscriminately court females Australian beetles attempt to copulate with discarded
beer bottles Even females, the more selective sex, sometimes make
erroneous choices ( 錯誤的選擇 ) In recently introduced invasive species that share
some traits with natives Natural selection has not had time to favor those
individuals that can successfully make the distinctions
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Signals that attract a mate
Must be species-specific Easy to locate Effective over long distances
Chemical and auditory signals are used Female silkmoth pheromones attract males from 100
meters away Auditory signals carry well
Amplified by communal displaying or anatomical or environmental structures
Courtship songs attract mates from long distances
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Female crickets gather on a loudspeaker that broadcasts the male’s courtship song
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Stop and think
When males signal to attract prospective mates, they give auditory or visual signals
Females that signal usually use the olfactory channel Why might this be so?
Think of the duration of receptivity, the costs of signals, and the dangers of signaling
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Communication: identifies the opposite sex
Individuals court before committing themselves to mating
Animals communicate their sex Differences between males and females are apparent i.e. antlers and other secondary sexual characteristic
Species showcase aspects of their body that indicate their sex A female stickleback reduces the probability of attack
by assuming a head-up position That displays her egg-swollen abdomen
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Identification of the opposite sex
Some gender differences are subtle Male blue-ring octopuses cannot distinguish males from
females Until late in the courtship sequence Octopuses mate by inserting their modified third right
arm in to the mantle cavity of the female And releasing a spermatophore (sperm packet)
Male blue-ring octopuses insert their arm indiscriminately into both males and females But only release spermatophores in females Male-male interactions are brief and not aggressive Fitness costs of making an insertion into a male are low
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Communication: mate assessment
Courtship allows a female to judge the qualities of her suitor So she can choose the one most likely to enhance her
own reproductive success More rarely, it allows the male to choose the
characteristics of an appropriate female Courtship displays provide a means for evaluating
the suitor’s qualities His physical prowess ( 身體能力 ) Ability to provide food for the offspring The extent of his commitment
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Female birds assess male quality
Male common terns ( 燕鷗 ) catch fish and offer them to the female She compares the quantity of fish provided by her suitors And chooses the best fisherman
Male wheatears, a small bird, collect stones in their beaks And carry them to cavities that serve as potential nest sites Females watch the males carry stones and even assess their
weight Male wheatears that carried heavier stones scored better on a
test of immunocompetence (an indicator of male health)
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Communication: coordinationof behavior and physiology
Male and female reproductive systems are not always synchronized Courtship displays can function to coordinate the couple’s
behavior and physiology 範例: ring doves
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The mating behavior of a pair of ring doves.
The sight of the female causes the male to increase his testosterone production, and he begins to display.
In response, the female coos ( 咕咕叫 ) , and her own vocalization stimulates estrogen production.
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Many courtship displays are visual or tactile
Displays coordinating receptivity occur at close range Some displays rely on pheromones delivered at close
range A male mountain dusky salamander’s courtship
pheromone makes the female more receptive The female indicates her receptivity and the male
deposits a spermatophore
Ayo 教材 (動物行為學 2010) 77
During courtship, a male dusky salamander injects a female with his courtship pheromone.
(a) the male alternately scrapes the female’s back with his teeth and swabs her with the pheromone, which is produced by a gland beneath his chin. The female signals her readiness to mate by placing her chin on the base of the male’s tail and straddling his tail.
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(b) the courtship pheromone makes the female receptive. Tail straddling and mating occur quickly when a female has been treated with a courtship pheromone compared to a control treatment with saline.
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Communication: maintenance of pair bonds
Formation of bonds between (relatively) monogamous pairs of animals
Pair-bond displays occur at close range Are visual or tactile
Dusky titi monkeys sit with their tails intertwined
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Pipefish maintain pair bonds year-round
Pipefish are long skinny fish related to seahorses Pairs are monogamous Male and female pipefish conduct a greeting ceremony
every morning Greetings are even carried out during the nonreproductive
season Functions solely to maintain the bond with the partner for
the next breeding season
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Maintaining social bonds
Social group members use communication to maintain bonds Based on contact: resting together, nuzzling, touching
Greeting signals assure nonaggression Chimpanzees greet each other by touching hands Sea lions rub noses Lions rub cheeks Cats head-bump
Social grooming is different from self-grooming Skin care is not the most important factor in social grooming
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Maintaining social bonds in primates
In primates, grooming smooths over tension and restores relationships after conflicts
Ayo 教材 (動物行為學 2010) 83
Alarm
Alarm signals warn another animal of danger Predators Guard against other members of their species bent on
infanticide or other form of aggression Alarm signals can cause animals to flee or assemble
Flee signals are easy to make quickly but difficult to locate Rapid visual signals: flash of a deer’s tail Volatile pheromones that diffuse quickly High-pitched sounds
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Alarms cause animals to flee or take cover
Species share similar alarm signals Some species even respond to the
signals of other species Eurasian red squirrels flee or
increase their vigilance when they hear the alarm calls of Eurasian jays
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Vervet monkeys use specific alarm calls
When a snake is seen, they emit a low-amplitude alarm call Capturing the attention of individuals near the caller Other monkeys respond by looking at the ground
With a leopard, monkeys make loud, low-pitched, abrupt chirps The call is audible from a great distance The caller is easy to locate by its fellows Monkeys scatter and run for cover
With an eagle, monkeys emit loud, low-pitched staccato grunts Easily located and transmitted over long distances Other monkeys run into thickets
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Alarm calls that cause animals to assemble
Alarm signals cause those who hear them to congregate To defend a resource Or drive off predators
Assembly signals need to easily locate the signaler Be longer-lasting And repetitive
Responses can be complex Ants respond to alarm pheromones by stopping. then
raising their heads, moving toward the source of the pheromone, and biting the enemy
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Aggregation
Animals aggregate for other reasons besides alarm calls To hibernate, share a resting place or a roost, prepare for
migration Bedbugs come out from hiding places and bite sleeping
humans They release an aggregation pheromone to find each
other Aggregating bugs have decreased sensitivity to
desiccation Protection from predators Ease of finding mates
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Agnostic encounters
Animals conflict with conspecifics over Food Territory Mates Their places in the dominance hierarchy
Are actions involved in conflict Aggressive behaviors Threats and attacks Submissive behaviors, appeasement or avoidance
Bighorn sheep butting heads, cats hissing, and dogs rolling on their backs
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The honeybee communication system
Honeybees are central-place foragers Leaving from a shared nest to collect food
All the labor is done by female worker bees Older bees forage for flowers, nectar and pollen Flowers can be widely scattered
Foragers communicate about the new food source to other bees Returning foragers do a characteristic dance Other bees follow dancers Karl von Frisch studied the dance language for 50 years
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The two dances of honeybees
Round dance: the bee runs in a circle, reverses direction and circles again
Waggle dance: the shape of a figure 8 During the central run, the bee waggles her abdomen
and buzzes her wings These dances indicate food sources and distance
information The round dance does not convey direction
information Tells recruits to “search for nearby food”
The waggle dance provides distance information
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(a) the round dance, performed after finding food near the hive. (b) the waggle dance, performed after finding food greater than
about 50m from the hive. During the waggle run through the center of the figure 8, the bee waggles her abdomen and buzzes her wings.
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The waggle dance provides distance information
After the waggle dance, bees appeared at the scent plate nearest to the original feeding station This dance says “food is far away” And also encodes information about direction and
distance by different aspects of the waggle dance
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After following a waggle dance, most recruits arrive at the scent plate nearest the site of the feeding station. The number of bees arriving at each station is indicated.
The setup of a fan experiment to determine whether bees use directional information.
The solid square shows the position of the feeding station during training, and squares show the position of the scent plates, which had no food.
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The setup of an experiment to determine whether bees use distance information.
The solid square shows the position of the feeding station during training, and circles show the position of the scent plates.
After following a waggle dance, most recruits arrive at the scent plate nearest the site of the feeding station.
The number of bees arriving at each station is indicated.
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Dances provide information about direction
The waggle dance helps a bee determine its departure direction
To know which way to go, bees need to know the angle formed by The sun’s azimuth (the point on the
horizon below it), the hive, and the flower
Dancing bees convey this angle
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Bees use the angle of the run with respect to gravity
The angle between the waggle run and “up” on the comb is the same as the angle formed between The flower, the hive, and the azimuth
If a bee needs to fly toward the sun to reach the flower The waggle run is oriented straight up
If the bee must fly directly away from the sun The waggle run is oriented straight down
If the food source is 20° to the right of the sun The bee does a waggle run 20° to the right of vertical
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Bees adjust the angle of their dances
To account for the earth’s rotation as the sun appears to move across the sky
Dancing bees adjust the angle of their dances by 15° an hour
These directions are not precise Dancing bees repeat their dances Observing bees take an average of the runs to select a
direction in which to fly Directions in the dance get bees to the general area of
the resource From there they use scent to pinpoint the flower’s location
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Dances encode information about distance
Distance to the food source is correlated with two features of the waggle run More waggles: the greater the distance to the food Longer sound trains of buzzes: greater distance to food
The two dances are not as discrete as they first appeared to be Round dances contain brief waggle phases that contain
distance information Round dances contain directional information but are
less precise than waggle dances.
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New technology offers additional insights
Tiny harmonic transponders attached to bees Return signals to a radar
Researchers can accurately map the paths of individual bees Bees that had followed a dance went straight to the
feeder They did not use odor cues to find the feeder
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Displaced bees
If bees leaving the hive were captured and displaced They did not fly in the true direction of the feeder But searched where the dancer had led them to expect the
feeder to be relative to their release point
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Researchers can “talk” to bees
By using a mechanical model of a dancing bee The model’s dance was not as effective as a live bee’s
dance Most recruits still showed up at the feeding station indicated
by the dance Wagging movements and buzzing are two critical
components of the dance
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Bees use optic flow to learn about distance
Bees rely on visual cues to estimate how far they have traveled And convey that information to other bees
Bees trained to fly into tunnels painted with vertical stripes overestimated the distance they flew The round dance is given when resources are within 50 m
of the hive The waggle dances are for longer distances All the tunnels were well within the 50 m mark
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Bees can be tricked
When bees flew through a tunnel with vertical stripes They acted as if they had flown a long way And performed a waggle dance
Even when the tunnel was only 6 m from the hive
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Other cues are also used in foraging
The waggle dance directs bees to a particular area But not that precisely
The location of the flower is pinpointed by odor cues Dance followers detect food scents on the dancers
Besides chemical they pick up from food Dancing foragers also produce other chemicals from their
abdomens These chemicals cause bees to become primed to look for
food
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Summary
Communication occurs when information is transferred from the sender to the receiver and the sender benefits, on average
Signal: a behavior that transmits information Communication channels: visual, auditory, chemical, tactile or
electrical, each with their own Effective distance, localization of sender, ability to go around
obstacles, speed of transmission, complexity, duration Pheromones: chemicals that convey information to conspecifics Vomeronasal organs sense chemical cues Multimodal communication: animals communicate using
signals from more than one sensory channel
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Summary
Communication is used throughout the reproductive process: To locate potential mates, signal their identity, advertise their
qualities as a mate, coordinate their physiology, and maintain pair bonds
Group-living animals maintain social bonds through touch Alarm signals warn of danger and cause receivers to flee or
assemble Animals communicate about the location of food resources Honeybee scouts communicate the direction of food with
A round dance (for nearby resources) or a waggle dance (for distant resources)