????(?)???(Physiological analysis) -????? (Ethology)

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????(?)???(Physiological analysis)-?????
(Ethology)
??? ??????????? (??)
2010 ? ??

• ???(Ayo)
• ?? ???? ???????
• ????????? ??

Ayo NUTN Web http//myweb.nutn.edu.tw/hycheng/
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Part 1. ????????? (????)

• ???? (History of the Study of Animal Behavior ).
• ???? (Genetic Analysis of Behavior ).
• ?? (Natural Selection and Behavior ).
• ????? (Learning and Cognition.)
• ???? (Physiological Analysis)
• (?) ???? (Nerve Cells and Behavior ).
• (?) ????? (The Endocrine System).
• ??(The Development of Behavior ).

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6b ????(?) ???

• The endocrine system
• How hormones influence behavior
• Methods
• Organizational and activation effects of hormones
• The dynamic relationship between hormones and
  behavior
• Interaction between hormones, behavior, and the
  environment
• A detailed look

4
The endocrine system

• Male plainfin midshipman fish display two
  reproductive strategies
• Type I males build nests and hum to court
  females
• Type II males sneaky cuckolders that dont build
  nests or hum
• Type II males sneak into the type Is nest and
  spawn or lie outside the entrance and deposit
  sperm there while fanning water toward the nests
  opening
• They must avoid detection by territorial males
• The sperm of the type II male competes with that
  of the type I male, who did all the work

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• The midshipman fishes are the genus Porichthys of
  toadfishes(??) .
• Typical midshipman fishes, such as the Plainfin
  Midshipman, are nocturnal and bury themselves in
  sand or mud of the intertidal zone during the
  day. At night they float just above the seabed.
• Some species are armed with venomous dorsal
  spines and are capable of inflicting serious
  injuries if handled.

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More differences between type I and II males

• A type I male is larger and takes longer to
  sexually mature
• Sonic muscles produce the droning hum (??????)
  attractive to females
• The specialized brain allows him to hum his
  courtship song
• He has large motor neurons to the sonic muscles
  and the brain center controlling those muscles
• Type II males become sexually mature sooner, but
  cant attract mates
• Sonic muscles are not well developed
• The ratio of testes to body weight is much higher
  than type Is

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A Type II male resembles a gravid female

• Because of his bulging(???) gonads
• His coloration is also similar to that of a
  female
• It is easier for him to lurk around the nests of
  type I males

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Sneaky cuckoldrya fixed behavioral strategy

• Type II males will not hold territories or court
  females even when both options are offered
• Their morphology prevents behavioral plasticity -
  the ability to switch to an alternative behavior
• Type I males cuckold other type I males if given
  the chance
• They take advantage of their large size and
  aggressively resist ejection by resident type I
  males
• They exhibit aggressive cuckoldry when not
  humming (????) and defending a nest

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??20HE protects female crabs

• A soft-shelled female is extremely vulnerable to
  predation
• By fish, octopus, other crustaceans - including
  other crabs
• The female releases 20HE (20-hydroxyecdysone) to
  deter (??) her mate from eating her
• It is not acting as a hormone (i.e. regulating
  molting)
• But as a pheromone a chemical substance that
  functions in communication between individuals of
  the same species
• 20HE may deter feeding in other species of
  predatory crustaceans

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Thus, a chemical signal may function

• Within an individual
• i.e. as a molting hormone in arthropods
• Between individuals of the same species
• i.e. as a sex-specific feeding deterrent during
  mating, and
• Between individuals of different species
• i.e. as a feeding deterrent

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Mechanism of action of peptide hormones

• Activates enzymes
• For long-term changes in protein function
• Examples luteinizing hormone (LH) and
  follicle-stimulating hormone (FSH)

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Mechanism of action of steroid hormones

• Once inside a cell, steroids combine with
  receptor molecules
• If binding occurs in the cytoplasm
• This complex moves to the nucleus
• And attaches to DNA
• Affecting gene expression and protein synthesis
• Takes hours or days and produces long-lasting
  effects on behavior

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How hormones influence behavior

• Hormones modify behavior by affecting
• Sensory or perceptual mechanisms
• Development or activity of the central nervous
  system, and
• Muscles important in the execution of behavior

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Effects on sensation and perception

• Hormones influence the ability to detect certain
  stimuli
• And the responses to and preferences for
  particular stimuli
• In some species, mate choice is based on
  hormone-mediated differences in the ability to
  detect stimuli
• Female domestic pigs are attracted to the
  boar(??) pheromone, 16-androsterone, while males
  are not
• Castrated males given the female hormone
  estradiol show female responses to a boar
• Hormones can mediate behavioral responses to
  stimuli
• Vasotocin a peptide hormone in non-mammalian
  vertebrates similar to the mammalian hormone
  vasopressin (????? )

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Vastocin influences mate choice in males

• Vasotocin enhances male responsiveness to female
  stimuli
• Male newts first rely on visual cues (i.e. size,
  shape, and color)
• Then switch to olfactory cues for close-up
  confirmation of species, gender, and reproductive
  state
• The male clasps the gravid female for hours in
  amplexus
• The female becomes sexually receptive

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• A newt is an amphibian of the Salamandridae
  family, although not all aquatic salamanders are
  considered newts.
• Newts are classified in the subfamily
  Pleurodelinae of the family Salamandridae, and
  are found in North America, Europe and Asia.

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Hormones can cause a change in preference in
animals

• Sex steroids can change social preferences
• Given a choice of social partner, young animals
  that received parental care prefer family members
• As they mature, they prefer non-family members
• Hormone-mediated changes in social preference are
  not limited to maturing animals
• In winter, adult female meadow voles prefer other
  females
• During mating season (spring and summer), they
  prefer males
• This reversal in preference is caused by higher
  estrogen levels, associated with longer days

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Effects on development and activity of the
central nervous system

• Circulating hormones affect behavior by
  influencing the central nervous system
• They influence different regions of the brain,
  including the
• (1) volume of brain tissue
• (2) number of cells in brain tissue
• (3) size of cell bodies
• (4) extent of dendritic branching
• (5) percentage of neurons sensitive to particular
  hormones
• (6) survival of neurons

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Hormones influence development of singing
behavior in birds

• In the zebra finch, sex differences in the brain
  nuclei that control song are established around
  the time of hatching
• Soon after hatching, the brains hormonal
  environment establishes sex differences in adult
  singing behavior (males sing and females do not)
• The steroid hormones involved in the early
  masculinization of the zebra finch brain are
  neurosteroids, not gonadal steroids

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Hormones affect muscles and motor neurons

• South African clawed male frogs emit six
  different calls
• The advertisement call allows females to find
  males
• Sexually receptive females produce a rapping call
• Unreceptive females tick
• Hormone-induced changes in the muscles of the
  larynx results in sex differences in calling
  behavior

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• Differences in the calling behavior of male and
  female clawed frogs result from the effects of
  hormones on the muscles of the larynx.
• (a) the males call consists of slow and fast
  trills
• (b) unreceptive female emit the ticking call.

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Hormones influence sex differences in muscles

• Most mammals have sexually dimorphic muscles and
  motor neurons
• Sex differences in the copulatory movements of
  adult rats result from early hormonal influences
• Specialized muscles control copulatory reflexes
  in male rats
• These muscles are present in both sexes at birth
• But are completely absent in adult females, due
  to a lack of androgen at birth

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An exception to the pattern

• Naked mole-rats (???) cooperatively breeding
  rodents living in colonies
• The queen is the only breeding female
• Subordinates and males show few sex differences
• The queens enlarged levator(??) ani muscle helps
  her deliver enormous numbers of offspring

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• Muscles of the perineum are sexually dimorphic in
  most mammals, being larger in males than in
  females as a result of the early effects of
  androgens. The levator ani muscle of the queen
  is larger than that of breeding males.

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Studying hormonebehavior relationships
interventional studies

• The experimenter manipulates the hormones of the
  animal
• Removes the endocrine gland
• Followed by hormone replacement therapy
• For example, testosterone regulates courtship and
  copulation in the male green anole
• What happens when the testes are removed?

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• Displays of the male green anole.

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Removal of testes changes behavior

• Removal led to a sharp decline in sexual behavior
  in green anoles
• Administration of testosterone reinstated this
  behavior
• Unlike sexual behavior, aggressive behavior only
  partially depends on gonadal hormones
• Its also influenced by social factors such as
  residence status

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• Effect of castration and testosterone replacement
  therapy on the courtship behavior of the male
  green anole.

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Interventional studies have become sophisticated

• Cannulation techniques(????) administer tiny
  amounts of hormone to specific regions
• Antihormones drugs that temporarily and
  reversibly suppress the actions of specific
  hormones
• The antihormone RU486 blocks progesterone (????)
  receptors
• Genetic knockout mice have a specific gene
  inactivated to eliminate the gene product (i.e. a
  hormone or hormone receptor)
• Progesterone receptor knockout (PRKO) mice do not
  respond to progesterone because they lack the
  appropriate receptors

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Male mice respond to hormones
Male laboratory mice are aggressive toward
infants and kill them

• Males with progesterone implants attack pups
• Males given RU486 dont attack pups

• PRKO male mice do not respond to progesterone
• Are not aggressive to infants

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Studying hormonebehavior relationships
correlational studies

• Researchers look for changes in behavior that
  parallel fluctuations in hormone levels
• Not as conclusive as experimental work because
  there is no evidence of causation
• One correlational study examined the relationship
  between testosterone levels and aggressive
  behavior in male song sparrows

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Correlation between behavior and hormones

• A close correlation exists between male song
  sparrow territorial and aggressive behavior and
  maximum levels of testosterone

• Testosterone increases aggressive behavior in
  song sparrows - but the reverse is also true

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Steroid hormones influence behavior through
organizational effects

• In organizational effects, steroids organize
  neural pathways responsible for certain patterns
  of behavior
• Occur early in life - just before or after birth
• Are permanent the brain or cells change
  structurally
• i.e. in the responsiveness of neurons to steroid
  hormones
• organizational effects on nonneural systems
• i.e. changes to the male western mosquitofish fin
  and its skeletal supports cause sex differences
  in mating behavior

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Activational effects

• Activational effects occur in adulthood and tend
  to be transient
• Lasting only as long as the hormone is present at
  high levels
• Involve subtle changes in previously established
  connections
• i.e. slight changes in neurotransmitter
  production or release along established pathways
• Not involved in gross reorganization of neural
  pathways

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Organizational activational effects of steroid
hormones in Norway rats

• Adult male and female rats differ in their sexual
  behavior
• Male behaviors social investigation, mounting,
  intromission, and ejaculation
• Female behaviors associated with
  solicitation(??) and acceptance(??)

• Differences in adult copulatory behavior are due
  to differences in the brains of male and female
  rats
• Differences are induced by irreversible actions
  of androgens in late fetal and early neonatal life

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The organizational effects of gonadal steroids on
sexual behavior

• Development of a male brain requires
  testosterone around the time of birth
• In the absence of testosterone, a female brain
  develops
• The effects of perinatal testosterone on adult
  sexual behavior are organizational
• Occur early in life and involve permanent
  structural changes in the brain

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• Pattern of sexual differentiation in the brain
  and behavior of the Norway rat.

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Steroid hormones have activational effects on
sexual behavior in rats

• Female rats with high estrogen and progesterone
  levels display feminine sexual behaviors when
  near a sexually active male
• Removal of the testes in an adult male eliminates
  copulatory behavior
• Steroid hormone effects on sexual behavior are
  activational
• Estrogen, progesterone and testosterone exert
  their effects by activating existing neural
  pathways.

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Adults vs. juvenile responses to sex steroids

• Activational hormones sex steroids in adults
  have only a transient activational effect on
  copulatory behavior
• By adulthood, the nervous systems of adult males
  and females have already differentiated
• The organizational effects of early steroid
  secretion have long since occurred
• Mature brains are not capable of responding to
  hormonal signals of the opposite sex

40
Individual differences in the behavior of male
tree lizards

• Individual differences are most pronounced in
  species with naturally occurring alternative male
  phenotypes
• Such as tree lizards
• The tree lizard has alternative male phenotypes
  that differ in aggressive behavior and color of
  the dewlap
• Aggressive males have orange-blue dewlaps
• Nonaggressive males have orange dewlaps

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• The Tree lizard or Ornate Tree Lizard (Urosaurus
  ornatus) is a species of lizard that is native to
  the southwestern United States and northern
  Mexico.

• The species has been used to research the
  physiological changes in the body during the
  fight-or-flight response as related to stress and
  aggressive competition. Also, its life history
  and costs of reproduction have been documented in
  field populations in New Mexico.

42
Nonaggressive males (relative plasticity
hypothesis)

• The differences are organized by steroid hormones
  during the neonatal period.
• The two types of males have similar hormone
  profiles in adulthood.
• Nonaggressive males are flexible in their
  territorial behavior, switching between sedentary
  (??) and nomadic(??) behavior in response to
  environmental conditions. (developmentally
  plastic)
• When conditions become stressful, the hormone
  corticosterone rises and ultimately reduces site
  fidelity(???), triggering nomadic behavior in
  nonaggressive males.

43
Developmentally fixed developmentally plastic
phenotypes

• When phenotypes are developmentally fixed, they
  cant change
• Caused by organizational effects of steroid
  hormones in neonates
• Developmentally plastic phenotypes can change
• Behaviors change in response to environmental
  conditions
• Changes in adult hormone levels reflect
  activational effects

44
A reciprocal relationship between hormones and
behavior

• Hormones can activate specific forms of behavior
• And behavioral stimuli can induce rapid changes
  in hormone levels

• Sexual stimuli can trigger a rapid increases in
  androgen levels
• In the marine toad, androgen levels increase with
  time spent in amplexus
• Suggesting that mating behavior induced the
  hormonal response rather than vice versa

45

• Changes in plasma androgen in male marine toads
  as a function of the time spent in amplexus.

46

• Amplexus (Latin "embrace") is a form of
  pseudocopulation in which a male amphibian grasps
  a female with his front legs as part of the
  mating process. At the same time or with some
  time delay, he fertilizes the female eggs with
  fluid containing sperm.

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Hormonal suppression of behavior

• Androgens and vasotocin mediate amplexus in newts
• Males clasp a female while she becomes sexually
  receptive
• What happens if a male in amplexus detects a
  predator?
• Does he continue with amplexus and hope for the
  best?
• Or terminate the behavior and seek a safe hiding
  place?
• The hormone corticosterone suppresses amplectic
  behavior
• Reducing the activity of neurons active during
  amplexus
• It acts via a receptor in the membrane of
  neurons, not by altering gene expression and
  protein synthesis

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Hormones rapidly change behavior

• The dynamic interactions between hormones,
  behavior, and the nervous system allow the
  behavioral state of an animal to shift rapidly
  and adaptively to changing environmental
  circumstances.
• Hormones allow an animal to adjust its behavior
  so that it is appropriate for the situation at
  hand
• Hormones, behavior, and the environment interact
  to generate adaptive behavior in the long term

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Adjusting to the environment

• Habitats of species provide different mating
  opportunities
• Associations between gonadal hormones and sexual
  behavior varies among species
• To allow the greatest number of surviving
  offspring
• A diversity of reproductive patterns exits in
• (1) production of gametes
• (2) secretion of sex steroids by the gonads, and
• (3) timing of mating behavior
• Three general patterns of reproduction exist in
  vertebrates associated, dissociated, and
  constant (but other patterns exist)

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Associated reproductive pattern

• Some animals (i.e. the Norway rat) exhibit a
  close temporal association between gonadal
  activity and mating
• Gonadal growth and increased levels of sex
  steroids activate mating behavior
• Found in most vertebrates studied

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Dissociated reproductive pattern

• Mating behavior is completely uncoupled from
  gamete maturation and secretion of sex steroids
• Gonadal activity occurs after all breeding
  activity has ceased
• Gametes are produced and stored for the next
  breeding season
• Gonadal hormones may not play a role in the
  activation of sexual behavior

52
Species exhibiting an associated reproductive
pattern

• Inhabit harsh environments with a predictable,
  but narrow, window of opportunity to breed
• Specific physical or behavioral cue triggers
  mating behavior
• Red-sided garter snakes range farther north than
  any other reptile in the Western Hemisphere
• The mating opportunity lasts 1 to 4 weeks
• Male courtship behavior is activated by increased
  ambient temperature following winter dormancy
• Not by testicular hormones

53

• The Garter snake is a Colubrid snake genus common
  across North America, ranging from Alaska and
  Canada to Central America. It is the single most
  widely distributed genus of reptile in North
  America.

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Hormones do not control red-sided garter snake
courtship

• Testicular activity is minimal in male snakes
  during the period between emerging from
  hibernation and mating
• Five to ten weeks after males have left the den
  site and no longer court females
• The testes grow and androgen levels increase
• Sperm produced is stored for use the next spring
• Males use environmental cues, not sex hormones,
  to determine mating season
• In females, changes in sexual attractivity and
  receptivity are mediated by physiological changes
  that occur as a consequence of mating

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Constant (opportunistic) reproductive pattern

• Characteristic of species in harsh environments
  (i.e. deserts)
• Suitable breeding conditions occur suddenly and
  unpredictably
• In desert-dwelling animals, reproduction is
  initiated by rainfall

• While waiting for breeding conditions
• Species maintain large gonads, mature gametes,
  and high circulating levels of sex steroids

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Zebra finches show a constant reproductive pattern

• Zebra finches live in the deserts of Australia
• Droughts last for years, so males and females
  maintain their reproductive systems in a constant
  state of readiness
• Rainfall produces flushes of grass seeds - food
  for young
• Courtship begins shortly after the rain starts to
  fall
• Copulation occurs within hours
• Nest building begins the next day
• Breeding readiness also varies with habitat
  predictability
• Birds in arid rangelands with unpredictable
  rainfall patterns keep high levels of
  reproductive readiness

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Onlookers(???) in the social environment

• Male Siamese fighting fish are spectacularly
  colorful
• They build mucus-covered bubble nests at the
  water surface
• Nests attract females and are home for eggs and
  hatched fry
• Males defend territories centered on their nest
• Social environment (presence/absence of an
  audience) and territory status (presence/absence
  of a nest) (onlookers)
• Influence aggressive behavior and hormone levels
  in males

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Evidence of hormone-mediated aggression

• Aggressive behavior and levels of 11KT (an
  androgen in fish that mediates aggressive
  behavior) in male Siamese fighting fish were
  influenced by male territory status and audience
• Males without a nest were less aggressive
• And had lower 11KT levels, when a female audience
  or no audience was present
• In the presence of another male, males were less
  aggressive
• And had lower 11KT hormone levels, when both had
  nests

60
Male Siamese fighting fish behavior

• Experimental setup for testing the response of
  male Siamese fighting fish to presence and type
  of audience.

61
Male Siamese fighting fish behavior

• In males, 11KT levels are influenced by the
  presence of a nest and an audience

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The hormonal basis of helping at the nest

• Helpers nonbreeding animals that assist the
  breeding pair in rearing young
• Providing food and protecting the young
• The evolutionary causes of helping helpers get
  some of their genes into the population even
  though they dont breed
• Florida scrub jays live in small groups in south
  central Florida scrub oaks
• Helpers offspring of the breeding pair from a
  previous year who remain on the territory and
  help raise siblings

63
Florida Scrub-Jay

• The Florida Scrub-Jay (Aphelocoma coerulescens)
  is one of the species of scrub-jay native to
  North America.
• It is the only species of bird endemic to the
  U.S. state of Florida.

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The physiological basis of helping behavior

• Helpers are physiologically capable of
  reproduction
• Their testes and ovaries produce hormones
• They can gather enough food to breed successfully
• Levels of the stress hormone corticosterone
  (suppresses production of reproductive hormones)
  equal breeders
• Prolactin levels increase through the breeding
  season, initiating parental care
• Females produce more prolactin than males
• Cues from the nest, eggs, and nestlings stimulate
  production
• Helpers have low prolactin levels because
  breeders wont allow them near the nest until the
  young have hatched

65
Prolactin levels are lower in helpers

• There is a relationship between a helpers level
  of prolactin and the feeding score (a measure of
  how much a bird fed the nestlings)
• Feeding score 0 helpers didnt help
• Prolactin levels of the helpers that did help are
  much higher

66
Scent-marking

• Scent-marking the act of strategically placing a
  chemical mark in the environment
• Many mammals apply urine, feces, or secretions
  from special scent glands on the digits, legs,
  chest, belly, head, or in the anal canal
• Many mammals have scent glands at multiple
  locations
• Scent marks convey information about individual
  identification, age, and reproductive state
• Establish and maintain territories and breeding
  relationship

67
Urine-marking by domestic dogs

• Urinary behavior is sexually dimorphic
• Adult males urinate more frequently than adult
  females
• And are more likely to urine-mark
• Urinary posture is sexually dimorphic males lift
  a leg to urinate, females squat
• Sex differences in urinary posture are organized
  by sex steroids (testosterone) around the time of
  birth
• But testosterone is not needed for the
  leg-lifting posture
• A neutered male still lifts his leg to urinate

68
Urine marking in female dogs

• Urine marking is more common than previously
  described for female dogs
• The propensity to mark with urine varies across
  the estrous cycle
• Most common just before and during estrus
• Conveys information about her reproductive state

69
Hormones affect salmon migration

• Adult Atlantic salmon leave the ocean and return
  to their natal stream to spawn in the fall
• Laying thousands of large, fertilized eggs in a
  gravel depression called a redd
• Parr very young salmon, 5 cm long, with vertical
  marks on their sides for camouflage
• Smolt 15 cm long fish that undergoes
  smoltification, which prepares them for migration
  to the ocean
• Dramatic changes in physiology, morphology, and
  behavior occur during changes from parr to smolt
• To prepare for migration

70
Atlantic salmon

• Salmon is the common name for several species of
  the family Salmonidae.
• Several other fish in the family are called
  trout the difference is often said to be that
  salmon migrate and trout are resident, a
  distinction that holds true for the Salmo genus.
• Salmon live along the coasts of both the North
  Atlantic (one migratory species Salmo salar) and
  Pacific Oceans (approximately a dozen species of
  the genus Oncorhynchus), as well as having been
  introduced into the Great Lakes of North America.

71
Young salmon change dramatically

• Parr marks are replaced by silver in smolt to
  evade (??) predators
• Young salmon change their position in the current
  
• Parr face into the current (positive rheotaxis)
  to see food coming
• Smolts face downstream (negative rheotaxis) for
  their impending migration to the sea
• Social behavior also changes
• Parr aggressively defend individual feeding
  territories
• Smolts exhibit decreased territorial and
  agonistic behavior and eventually form schools

72
Environmental factors initiate and hormones
mediate changes

• Environmental factors (i.e. high water flow and
  increasing photoperiod and temperature) prompt
  smoltification
• Hormones mediate physiological and morphological
  changes
• Prolactin decreases during smoltification
• Growth hormone increases and increases tolerance
  for saltwater
• Cortisol promotes acclimation to a particular
  environment
• Thyroid hormones replace parr marks with silver
  coloration

73
Summary

• Transfer of internal information by the endocrine
  system occurs slowly, with general, long-lasting
  effects
• Communication occurs through hormones and
  neurohormones that produce changes at the
  cellular level
• That ultimately influence behavior
• Two types of hormones are peptide and steroid
  hormones
• Hormones influence behavior by affecting
  sensation, the central nervous system, or muscles
  responsible for the execution of behavior
• Effects of steroid hormones on behavior have been
  divided into organizational and activational
  effects

74
Summary

• Hormonal effects on behavior can be studied by
  interventional studies or correlational studies
• Hormones initiate changes in behavior
• And behavior can causes changes in levels of
  hormones
• Interactions between hormones and behavior are
  sensitive to the physical and social environment
• Behaviors mediated by hormones include
• Aggression, courtship, mating, caring for young,
  scent-marking, and migrating

75
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• Ayo ?? NUTN ? http//myweb.nutn.edu.tw/hycheng/