發育 (Development) ─ 動物行為學 (Ethology) 鄭先祐 (Ayo) 國立臺南大學...

發育 (Development)

─ 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 1. 動物行為的研究途徑 ( 個體行為 )

歷史背景 (History of the Study of Animal Behavior ).

基因分析 (Genetic Analysis of Behavior ). 天擇 (Natural Selection and Behavior ). 學習與認知 (Learning and Cognition.) 生理分析 (Physiological Analysis)

( 一 ) 神經細胞 (Nerve Cells and Behavior ). ( 二 ) 內分泌系統 (The Endocrine System).

發育 (The Development of Behavior ).


07 發育 (Development)

Influences on Behavior development The concept of sensitive periods The development of bird song Developmental homeostasis


The development of behavior

A newly hatched mallard duckling Responds to its mother’s alarm call by “freezing” Responds to its mother’s assembly call by following her

Changes that occur during behavioral development contribute to fitness Immediately (i.e. the freeze response) And in adulthood (i.e. mate preference)


The Mallard, or Wild duck (Anas platyrhynchos), probably the best-known and most recognizable of all ducks, is a dabbling duck which breeds throughout the temperate and sub-tropical America, Europe, Asia, New Zealand (where it is currently the most common duck species), and Australia.

The male birds have bright green head, while the female is light brown. The Mallard lives in wetlands, eats water plants, and is gregarious. It is also migratory. The Mallard is the ancestor of all domestic ducks, and can interbreed with other species of genus Anas. This interbreeding is causing rarer species of ducks to become genetically diluted.


Early behavioral development of a duck

Questions about development How does genetic makeup interact with the internal and

external environment? How do the nervous and endocrine systems influence

behavioral development? How do visual, auditory, or social stimuli affect

development of behaviors? Are early experiences important? What happens when a behavior stops? Does development always proceed predictably and reliably?


Development of the nervous system

Behavior is primarily controlled by the nervous system and is intimately linked with its development Particularly early in life When development of the nervous system is rapid and

dramatic This is seen in the neural and behavioral

development of embryonic Atlantic salmon


Behavioral development in the Atlantic salmon. Patterns of behavior emerge in parallel with the development of neural structures necessary for their performance.


Development of an embryonic Atlantic salmon

The embryo’s heart and dorsal muscles move first Before the nervous system has formed

Next, the major motor systems appear in the spinal cord Motor neurons contacting anterior muscles allowing flexion The trunk’s sensory system develops and connects to the

skin The neural circuits for fin and jaw movements are complete Neural and behavioral development continues - all before

hatching Development of the nervous system underlies the

appearance of new patterns of behavior


What happens to neural circuits when a behavior disappears?

Neural circuits can be dismantled or permanently altered

For example, changes occur in the tobacco hornworm during complete metamorphosis

Metamorphosis entails dramatic changes in morphology and behavior The nervous system must control three stages: larva

(caterpillar), pupa, and adult moth


The larva of Tabacco hornworm (Manduca sexta)


Metamorphosis of the tobacco hornworm

The neural circuitry controlling stage-specific patterns of behavior is assembled and dismantled during development

Caterpillars have abdominal prolegs They act in withdrawal reflexes, crawling and grasping the

substrate Proleg behaviors are not important to the pupa and

disappear during the larval–pupal transformation


What causes the disappearance of prolegs?

Proleg movements are accomplished by retractor muscles Innervated by motor neurons with branching arbors

(dendrites) During the larval–pupal transformation

Dendrites of the motor neurons regress As these motor neurons die, their associated proleg

muscles degenerate and become nonfunctional.


Why do neurons die?

Just before the transition to the pupal stage, high levels of ecdysteroid hormones trigger regression of the dendrites of the motor neurons that innervate the proleg muscles Motor neurons are removed from behavioral circuits

and proleg behaviors are lost in the pupa


The peak in ecdysteroid hormones just before transformation to the pupa triggers dendritic regression.


Development of nonneural structures

Behavioral change can be driven by non-neural morphological changes To perform a behavior, the animal has to develop the

necessary morphological structures Paddlefish feeding behavior changes

Larval paddlefish chase and eat zooplankton Adults consuming material strained from the water


Paddlefish change feeding behaviors

Changes in behavior are coordinated with development of specific morphological structures

Changes in paddlefish feeding behavior parallel the development of gill rakers ( 鰓耙 ) Which strain food particles from the water Begin to develop when young fish are about 100 mm long

(4 inches) Are well-developed when young fish reach 300 mm long Feeding behavior takes on the fully adult pattern of

indiscriminate filter feeding


The hormonal milieu( 背景 ) influences behavior

Developing animals are influenced by the hormonal milieu (environment) they experience early in life

Two examples describe the effects of exposure to androgens, such as testosterone, during the prenatal period House mice Black-headed gulls


The Black-headed Gull or Pallas's Gull, Ichthyaetus ichthyaetus, is a large gull. This species breeds in colonies in marshes and islands from southern Russia to Mongolia. It is migratory, wintering in the eastern Mediterranean, Arabia and India. This gull nests on the ground, laying between two and four eggs.

House mice


Prenatal ( 胎兒期的 ) exposure to androgens: house mice

In the uterus, each fetus has its own placenta Even before birth, their

endocrine glands produce hormones

They can permanently alter their own and their neighbor’s morphology, physiology, and behavior


Fetal development can be modified by others

Development of mouse fetuses ( 鼠胎 ) can be modified by exposure to hormones secreted by contiguous ( 接觸的 ) littermates( 同窩出生者 )

Fetuses can take three intrauterine positions relative to siblings of the opposite sex Females nestled between two male littermates have

higher concentrations of testosterone than female fetuses not next to males

Hormones pass through the amniotic fluid of contiguous littermates


Exposure to prenatal hormones affects adult mouse behavior

As a result of prenatal exposure to testosterone, adult females that were between two males in the uterus (1) are less attractive to males (2) are more aggressive to female intruders (3) mark a novel environment at a higher rate (4) maintain larger home ranges (5) experience their first estrus at a later age and (6) produce fewer viable litters


Prenatal exposure to androgens influences young birds

A mother bird deposits androgens into the yolk of eggs In black-headed gulls, androgen levels increase with each

egg laid Higher androgen levels led to: earlier hatching; enhanced

growth and begging for food, and lower immune function Chicks direct energy to growth and competitiveness rather

than to immune function Adult birds show more frequent courtship and threat

displays, win more aggressive encounters, and lower survival

Greater deposition of androgens in last-laid eggs may enhance the growth and competitiveness of these chicks


The environment affects behavior

The environmental temperature during embryonic development affects behavior i.e. leopard geckos have temperature-dependent sex

determination chromosomes do not determine sex

In leopard geckos, incubation temperature: Determines an individual’s gender Influences the adult’s aggressive and sexual behavior Affects behavior involve in mate choice


Reproduction of leopard geckos

They are also known to have temperature-dependent sex determination (TSD).

Research shows that more females can be produced in predominantly cool temperatures (about 26-30˚ C) and very warm temperatures (about 34-35˚ C).

It was recorded that males can be produced at the intermediate temperatures (about 31-33˚ C).

Those born in the warmer temperatures expressed more aggressive behavior. These are known as "hot females" and are often determined to be infertile, that is unable to reproduce.


Temperature affects gecko mate choice

Incubation temperature influences brain development Individuals have different perceptions of the opposite

sex A physical characteristic of the prenatal

environment influences the development of adult behavior


Males reared at 30º C prefer females reared at 34º C

Males reared at 32.5º C prefer females reared at 30º C


The postnatal environment also influences development and behavior

Comparing neural and behavioral development in captive animals reared in enriched or standard laboratory housing conditions

Enriched environments provide: Larger cages A more complex and variable physical environment Nesting material, foraging devices, toys, hiding places The opportunity for voluntary exercise Complex social groups


Environmental enrichment changes the brain and behavior

In rodents, environmental enrichment caused structural changes in the brain Increased numbers of neurons, synapses, and dendritic

branches Increased brain weight and size

They also exhibit enhanced learning and memory In captive nonhuman primates, individuals in enriched

environments exhibit a more balanced repertoire of natural behaviors


Enrichment reduces abnormal behaviors

Captive nonhuman primates exhibit fewer abnormal behaviors Self-injurious behaviors (e.g., self-biting and head-banging)

and Stereotypic behaviors (i.e. pacing and flipping, with no

apparent biological function) Abnormal behaviors develop in response to unavoidable

stress or fear And the inactivity, boredom, and frustration experienced in

environments lacking physical and social complexity


Experience through play

Play is important in the normal development of behavior In many mammals, birds, reptiles and some

invertebrates But Play is easy to see, hard to define


Play is easy to see, hard to define

It is difficult to define: there is no specific behavior pattern or series of activities that exclusively characterize it It borrows or exaggerates other behavior patterns

Play draws elements from other, functionally different behavior patterns juxtaposed in new sequences i.e. mixing components from hunting and sexual behavior

Movements are repeated more often than during non-play An aggressive dog bares its teeth, growls, and raises its hair But during a play fight, hair is not raised

It is spontaneous, voluntary, and exhibited by healthy individuals


Various forms of play

Social play: play fighting, play chasing, sexual play Kittens and puppies chase, wrestle, and pounce Playful mounting by gazelles, precocious courtship in

turtles Locomotor play: exercise

Foals kick up their heels and gallop Young primates, including humans, swing, roll and slide Polar bear cubs climb ashore only to leap back into the

water Object play: manipulates objects

After an initial investigation, an object may become a toy Animals can change the type of play

And the form of play may change as the animal matures


The long-term significance of play

Physical: training for strength, endurance, and muscular coordination Particularly for intraspecific fighting and prey capture

Social: practice of social skills (i.e. grooming and sexual behavior), establishment and maintenance of social bonds Also helps develop an animal’s ability to read and send

signals to communicate with other members of its species

Cognitive: learning specific skills or improving overall perceptual abilities

Play may fit into more than one category


The concept of sensitive periods

Play, the physical environment, and changes in the animal’s nervous system or hormonal state can cause behavioral changes during development These factors have their effects during particular

windows of time, called sensitive periods Critical periods: windows of opportunity for learning

A phase of susceptibility to environmental stimuli Brief, well defined, during which exposure to certain

stimuli produce irreversible effects on subsequent behavior

The term “sensitive period” has replaced this term


The sensitive period

Sensitive period: a time during development when certain experiences have a greater influence on the characteristics of an individual than at other stages

Why do sensitive periods in most animals occur early in life? Animals have the greatest opportunity to gain knowledge

from parents and close relatives For example, young birds learn to recognize conspecifics

during a brief sensitive period before leaving the nest During sensitive periods, animals learn appropriate cues,

not only of conspecifics, but also of the local environment


Sensitive periods allow animals to learn about the environment

Salmon must learn the precise location of their natal stream because each population is finely adapted to its home water

Before their migration to the sea and during a sensitive period, Juvenile salmon learn the water’s unique chemical

composition (HSOB - home stream olfactory bouquet) at the site where they were spawned

The sensitive period for learning the HSOB occurs when smolts become ready for seaward migration and life


Multiple sensitive periods

Individuals can experience multiple sensitive periods during their development

A young male songbird has sensitive periods during song learning And during sexual imprinting (learning the characteristics

of an appropriate mate) Humans have multiple sensitive periods during visual

development Different sensitive periods occur for different aspects of

vision (visual acuity, peripheral vision, motion detection)


Sensitive periods in filial( 子女的 ) imprinting ( 印痕 ) Chicks, ducklings and

goslings follow their mother They develop a preference

for characteristics associated with their mother This attachment is unfailing,

and young even follow human “mothers”


Goslings following their “mother”, Konrad Lorenz. Lorenz was the first scientist to study imprinting experimentally.

Greylag goose


Imprinting is immediate and irreversible

Two processes are involved in development of following a mother Development of the predisposition( 傾向 ): a

young bird is predisposed to approach objects resembling conspecifics

In filial imprinting( 子女的印痕 ), the young bird learns, through exposure to its mother, her characteristics and then preferentially follows her


Filial imprinting in precocial young

The two processes – development of the predisposition and filial imprinting – are localized in different regions of the brain

Filial imprinting is studied in species with precocial young, who can move about and feed on their own shortly after hatching Occurs in ducks, geese, swans, chickens, turkeys, and

quail The following response is nonexistent in young

songbirds, who are altricial – helpless in the nest

※ Precocial 剛孵化便能立即活動的

※ Altricial 孵出時光禿無毛 , 需要母鳥照顧一個時期的


Imprinting in mallard ducklings

The auditory stimulus of the maternal call is important in filial imprinting Ducklings respond to the maternal call of their own

species without any previous exposure to it This response is an example of the predisposition

process


A stuffed Peking hen emitting mallard calls was more effective in eliciting the following response in incubator-reared Peking ducklings( 北京小鴨 ) than a hen emitting either wood duck or chicken calls.


Mallard ducklings have a sensitive period

Auditory experience before hatching is important It induces a predisposition to follow the mallard mother’s

assembly call During their sensitive period, they must hear their own

contentment calls or those of their siblings For them to prefer the call of a mallard hen

The sensitive period occurs during embryonic development Exposure after hatching does not producing the preference

for the normal call of their species Ducklings with normal embryonic auditory experience

always choose a mallard’s call over a chicken’s


Visual stimuli affect the following response

Both auditory and visual stimuli are critical for the following response Auditory stimulation from the mother prompts

ducklings to leave the nest and follow her The hen’s appearance becomes important after leaving

the nest


Important generalizations about early behavioral development in ducklings

Embryonic experience also influences behavior Many stimuli go into developing a single pattern of

behavior The importance of different stimuli changes as the

young animal matures Visual and auditory stimuli are important in the following

response The priorities of these cues match the timing of

development of these systems


Sexual imprinting in birds

Sexual imprinting: early experience with parents and siblings influences sexual preferences in adulthood for many species Sexual preferences develop after filial preferences Although the sensitive periods may overlap Sexual imprinting is shown in the preferences of

sexually mature birds for individuals of the opposite Sex Unlike filial imprinting, sexual imprinting occurs in both

altricial and precocial birds

※ Precocial 孵化後，能立即活動的

※ Altricial 孵出後光禿無毛，需要母鳥照顧一個時期的


Sexual imprinting in the altricial zebra finch

Given a choice, male zebra finch raised by Bengalese finches courted Bengalese females

Brief contact with foster parents early in life exerts a more powerful, longer-lasting influence on mate preference than long-term social contact in adulthood However, most eventually mate with a conspecific

female Sexual imprinting occurs in two stages:

The acquisition stage ( 獲取階段 ) The consolidation stage ( 鞏固階段 )


Bengalese Finch

Zebra Finch


The two stages of sexual imprinting

The acquisition stage A young male forms a social bond to its parents Because of this bond, the male prefers to socialize with

members of its parents’ species This preference guides his first courtship attempts

The consolidation (stabilization) stage The male courts a female for the first time During courtship, the social preference for the parental

species becomes linked to sexual behavior Once ended, no new preferences can be established


Acquisition and consolidation are different processes

The strength of the social preference in the acquisition phase is influenced by the amount of food fed to the young male

Consolidation is most affected by the degree to which the male is aroused at the time of courtship

The functional significance of sexual imprinting Animals learn to identify and choose mates similar but

not identical to their family members


Sexual imprinting in the precocial Japanese quail

They prefer to mate with individuals that are similar yet slightly different from members of their immediate family They judge genetic distance by plumage characteristics

Males and females prefer to spend time near first cousins Siblings are too familiar Novel unrelated animals are too different


Japanese quail prefer to spend time near individuals that are similar to, yet slightly different from, members of their immediate family. (a) apparatus used to test preferences of adult quail.

(b) both male (shown as triangles) and female quail (shown as circles) prefer first cousins.


Sexual imprinting in free-living birds

Great tits cross fostered to blue tits preferred their host species Sexual imprinting had occurred

Blue tits cross-fostered to great tits mated with conspecifics They had not sexually imprinted on their host species

Pied flycatchers cross-fostered to blue and great tits did not sexually imprint on either host species

Decreased sensitivity to sexual imprinting occurs in Solitary rather than social species Polygynous rather than monogamous species Cross-fostering to a socially dominant or distantly related

host species


Sexual imprinting

← Great tits

← Blue tits

Pied flycatchers →


Do mammals sexually imprint?

In cross fostered sheep and goats Males strongly preferred foster females, even after years

of exposure to their genetic species Females had weaker, reversible preferences for foster

males They learn characteristics of an appropriate mate from

their mother Facial features are critical in forming social and mating

preferences in mammals


Maternal attachment

Another imprinting-like process in mammals Some ungulate species form a lasting bond between the

mother and young right after birth The mother cares exclusively for her own offspring Precocial young can wander away from their mother

soon after birth The bond must be established early


Development of the mother’s attachment

The mother-young bond depends on mutual recognition and bonding

Right after parturition, mothers accept any young Mothers are maternally responsive but not selective Attachment requires maternal contact with offspring during

sensitive periods immediately after birth Developing maternal attachment in sheep and goats consists of

Activation of maternal responsiveness - the display of maternal behavior when in the presence of young and

Establishment of maternal selectivity - directing maternal behavior only toward young the mother has bonded with


Sensitive periods for responsiveness and selectivity

Undisturbed female sheep and goats display maternal behavior within minutes of giving birth If the young is removed before she has had contact with it,

maternal responsiveness permanently fades within hours A few minutes or hours of contact maintains responsiveness The sensitive period lasts from birth to 12 hours postpartum

The sensitive period for development of selectivity lies within the sensitive period for maternal responsiveness (2 hours postpartum) Most mothers need only 30 minutes of contact with offspring

during the sensitive period to display selective behavior


Which cues are important in maternal bonding?

The mother’s olfactory system is vital in both processes Particularly olfactory cues from the amniotic fluid However, the two processes differ in their ability to

compensate for loss of olfaction Loss of olfaction prevents the development of maternal

selectivity but not maternal responsiveness Without olfactory cues, mothers rely on other sensory

cues from neonates to display maternal behavior However, they do not selectively respond to their own

offspring


Brood care in ants

Other animal groups also have sensitive periods Ants live in complex societies

Labor is divided Roles change dramatically and repeatedly over a few

weeks In the Neotropical ant, an individual’s job changes

with age Ants isolated 2 days after emergence had the most

serious abnormalities


Ants have sensitive periods

The sensitive period: the first four days after emergence When workers are isolated immediately after

emergence, their development is simply put on hold Reintroduction into the colony mimics an emergence

It is not the physiologically defined first four days of life that is important for the development of brood care behavior But the first four days of social contact

The sensitive period must be uninterrupted to ensure normal behavioral development


The development of bird song

There is a continuous interplay between the developing bird and its internal and external environment

The zebra finch: a social Australian species Song functions in mate attraction Only males sing Females are attracted to their song Males tolerate other birds, except in the immediate

vicinity of their nests


The neural substrates of song.

Song nuclei: several areas of the brain are involved in song Posterior pathway: involved in song production Anterior pathway: involved in song acquisition

Other areas of the brain function in song perception (hearing) And in the storage of memories of song heard when young


Sexual differentiation of the zebra finch brain

Zebra finches have obvious neuroanatomical sex differences Male song nuclei have more and larger neurons This is not true for all songbird species

Genes on the sex chromosomes affect the brain’s synthesis of estrogen Higher estrogen levels in male brain tissue

masculinize the song system


Hormonal effects on singing

Hormones have both organizational and activational effects on singing behavior Estrogen early in life organizes development of a male

song system High testosterone levels in adulthood activates singing

behavior Brains are not always sensitive to the organizing effects

of estrogen The brain is sensitive to hormonal influences around the

time of hatching When estrogen affects the developing nervous system


Hormonal activation of song is seasonal

Song occurrence is related to the breeding season Song nuclei also change in seasonally breeding birds

Increases in neuron number, density, metabolic capacity, and spontaneous neurophysiological activity

Gonadal testosterone and its metabolites act on the song nucleus (the HVC) Which then influences other song nuclei


Role of learning in song development

White-crowned sparrows are songbirds from North America

A young male sparrow hears the songs of his father and other adult males during his first summer and autumn

He produces only subsong A highly variable, rambling series of sounds The syllables are not typical of the full song of adult males


White-crowned sparrow songs develop

As the first breeding season approaches, “plastic song” occurs in the male His song begins to contain elements recognizable as

white-crowned sparrow syllables As the male continues to refine his song, his song crystallizes

By his first breeding season, he produces the full song of adult males

Imitations of those he heard many months before The sensitive period for song learning is between 10 and 50

days posthatching Young male reared in isolation develop abnormal song


The role of auditory feedback in song learning

For song to develop normally, male white-crowned sparrows must Hear adult males of their species sing Hear himself sing And compare his vocal output to songs he memorized

Auditory feedback is needed For song development But maybe not for maintaining song Depending on song complexity or the ability to modify

songs in adulthood


Sonograms of songs that were produced by white-crowned sparrows (a) reared under natural conditions, (b) reared in social isolation, and (c) deafened at an early age.


The phases of song development

Sensory phase: songs are learned and stored Males learn only subsong, which does not involve

retrieval or rehearsal Acquisition: song is learned Storage: song is retained in memory

Sensorimotor phase: singing learned song actually begins Retrieval and production - learned song is rehearsed

and matched to the sounds they memorized months earlier

Motor stabilization - song is crystallized into final adult song, remaining unchanged for the rest of his life


Songs can be dropped or modified

Young males may drop songs from their plastic song repertoire Ending up with 8-11 songs

Songs are not dropped at random Songs that don’t match neighbor’s are discarded

Sharing songs helps neighboring males communicate Allow them to avoid costly territorial battles

Modifying songs make them less similar to neighbor’s songs May promote individual recognition

Song learning is a balance between copying the songs of neighboring males and the need for individuality


Sensitive periods in song learning

Sensitive periods have some degree of flexibility or variability They are influenced by environmental conditions Wide variation exists among and within songbird

species The sensitive period’s length and timing for learning varies

Lifelong learners (open-ended species) continually revise their songs throughout adulthood, i.e. canaries

Age-limited learners (closed-ended species): the period of learning occurs during the first weeks or months of life

i.e. white-crowned sparrows and zebra finches


How do male cowbirds learn their songs?

Brown-headed cowbirds are brood parasites Females lay eggs in other species’ nests Foster parents raise the babies

Shouldn’t they sing their foster parent’s songs? But adult males sing cowbird song

When does the sensitive period for song learning occur in brood parasites? It is delayed to give them time to hear the songs of

adult male conspecifics


Brown-headed cowbirds are brood parasites

Brown-headed Cowbird females can lay 36 eggs in a season. More than 140 different species of birds are known to have raised young cowbirds.


Sensitive periods for song learning vary within a species Individual differences in the timing of song learning can

be understood in the context of life histories Maximizing the chances that each male develops

species-appropriate singing behavior In the marsh wren, vocal learning is influenced by

photoperiod Males that hatched late in the breeding season learned

songs the following spring Late hatched young that disperse further than early

hatched young learn songs the following spring from neighbors


Own-species bias in song learning

Social interactions in song learning are very important Own-species bias: when given a choice, young male

birds learn their songs from conspecifics Learning the songs of their own species more rapidly

and accurately than those of a different species But, live tutors of another species can override the

bias for learning taped conspecific songs Young male sparrows learn the song of the adult that

they are allowed to interact with Even if this adult belongs to another species


Social factors and song development

Cowbird song development is influenced by interactions with conspecifics in flocks

Cowbird song development is influenced by interactions with conspecifics in flocks Males living in mixed-sex groups learn to suppress their

song to avoid attacks from dominant males Adult males influence the potency of song produced by

young males and also the rate at which song develops.


Female cowbirds prefer the songs of males reared in isolation to those of male reared socially.

Males without visual or direct contact with dominant males produce more potent songs than do males that have visual or direct contact. In cowbirds, young males learn to modify their songs to avoid attack by adult males.

Male cowbirds reared in isolation had more appealing songs than group-reared males


Females help shape songs of males

Male cowbirds housed with conspecifics or other species developed different songs Song development was biased toward their female

companions’ preferences Even if they are different species

Males housed with females from their own population developed stereotyped (full) song faster than males housed with females from a different population


Important factors in shaping bird songs

Female cowbirds influence male song development Not by song, but by moving one or both wings rapidly

away from the body Male cowbirds adjust their songs to their audience

To avoid conflict with males and stimulate available females

Social factors help shape the songs of other songbird species The “selective attrition” phase: young males drop songs

from their plastic song repertoire that don’t match their neighbor’s


A diversity of song learning strategies

Songbirds exhibit diverse song learning strategies The sensitive period, when young males learn song, ranges

from a brief period early in life to lifelong learning Social isolation produces abnormal song in many species Diversity exists in the number of songs that birds learn

Most birds sing less than 5 songs But some birds sing > 2,000 songs

Young males copy tutor songs Some males imitate tutor songs Others modify or invent species-typical songs that bear

no resemblance to tutor song


Stop and think

How is it best to raise young songbirds brought to wildlife rehabilitation hospitals so they can return to their natural habitats?

Song is vital to survival and breeding success In territory maintenance and mate attraction

If you were charged with developing guidelines for housing and tutoring young songbirds brought to your rehabilitation facility, what factors would you consider in making your recommendations?


Developmental homeostasis

Individuals develop under different physical and social conditions, and still display species-typical, normal behavior

Developmental homeostasis: developmental processes can buffer themselves against potentially harmful influences to produce functional adults Despite diverse experiences, behavioral development

proceeds in a predictable and reliable manner The developmental process demonstrates stability and

resilience under constantly changing variables Recovery of profoundly isolated chimpanzees illustrates the

resilience of the developmental process


Rehabilitation of chimpanzees after long-term isolation Male chimpanzees were separated as infants from their

mothers and conspecifics and taken to a laboratory between 1976 and 1986 to use in hepatitis and HIV research They were individually housed in cages

All experienced early maternal separation, spatial confinement, and lack of control over their daily lives They differed in when social deprivation began and the

total duration of social isolation Some had been kept in isolation for 21 years

When moved to a new facility and allowed to socialize, they became members of an all-male or mixed-sex groups


Timing and duration of social deprivation influences chimpanzee responses

Chimps cope better with social stressors than environmental stressors Chimps perceive they have greater control over social

situations Chimpanzees that have experienced profound social

isolation, can recover and live less stressful lives with conspecifics


Summary

Patterns of behavior appear, disappear, and alter as animals develop

Behavioral change comes about through development, hormones and experience

Play is vital to behavioral development: social play; locomotor play (exercise); and object manipulation It improves physical condition, develops social skills and

bonds, and helps develop and maintain cognitive skills Genes, hormones, the environment, experience and social

situations interact to develop sexually dimorphic behaviors


Summary

Sensitive periods: periods of enhanced sensitivity to environmental stimuli Characterize behavioral phenomena, including

filial imprinting sexual imprinting, and maternal attachment

There are tremendous differences among species and individuals in the timing of sensitive periods

Animals encounter a wide variety of physical and social conditions, and most develop normally

Developmental homeostasis: Development proceeds in a normal fashion in the face of environmental perturbation


問題與討論

[email protected]

Ayo 台南 NUTN 站 http://myweb.nutn.edu.tw/~hycheng/

發育 (Development) ─ 動物行為學 (Ethology) 鄭先祐 (Ayo) 國立臺南大學...

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Transcript of 發育 (Development) ─ 動物行為學 (Ethology) 鄭先祐 (Ayo) 國立臺南大學...

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Transcript of 發育 (Development) ─ 動物行為學 (Ethology) 鄭先祐 (Ayo) 國立 臺南大學...

發育 (Development) ─ 動物行為學 (Ethology) 鄭先祐 (Ayo) 國立臺南大學...

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