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Chapter 59: Animal Behavior


Chapter Outline

Chapter 59: Animal Behavior

59.0 Introduction
  1. Animal Behavior Allows Animals to Adaptively Respond to Environment
    1. Behavior Develops in Individuals fig 59.1
    2. Environment Influences Biological Processes that Mediate Animal Behavior
59.1 Ethology focuses on how neural units influence behavior
  1. Approaches to the Study of Behavior
    1. Behavior Bridges Several Biological Disciplines
      1. Linked with evolution, ecology, physiology, genetics, psychology
        1. Each has different perspective
        2. Addresses slightly different questions
      2. Behavioral studies have contributed to understanding other areas
        1. Includes nervous system organization, child development, human communication
        2. Also process of speciation, community organization, mechanism of natural selection
      3. Study of nonhuman behavior extrapolated to humans
    2. Aspects of Behavior
      1. Behavior: Way an organism responds to stimuli in its environment
      2. Patterns of behavior may be simple or complex
      3. Depends on organism and its environment
        1. Nervous system and behavior became more complex along with one another
        2. Nervous systems perceive and process information, trigger adaptive motor responses that are patterns of behavior
    3. Explanation of Behavior
      1. Proximate causation
        1. Explains how behavior works, internal state provides physiological basis
        2. Study by measuring physiological events
          1. Measure hormone levels
          2. Record nerve impulse activity
        3. Example: Male songbird sings during mating season
          1. Due to level of sex hormone, testosterone
          2. Binds to receptors in brain, triggers production of song
      2. Ultimate causation
        1. Explains why a behavior evolved
        2. Study by measuring influence on survival or reproduction
        3. Example: Defend territory or attract females by singing bird song
      3. Influences that shape behavior
        1. Nature: Instinct and genes determine behavior
        2. Nurture: Experience and learning influence behavior
        3. Two extremes are not mutually exclusive, but work together to influence behavior
    4. Ethology
      1. Study of the natural history of behavior
      2. Founding fathers had formal training in zoology and evolution fig 59.2
      3. Ideas explained stereotyped behavior
        1. Behavior is instinctive or innate, product of natural selection
        2. Appeared in same form in different individuals of a species
        3. Based on pre-programmed neural circuits from genetic blueprints
      4. Example: Goose returning egg to nest
        1. Will complete behavior even if egg is removed during retrieval
        2. Sign stimulus (key stimulus): Triggers behavior = egg out of nest
        3. Innate releasing mechanism: Provides neural instructions for motor program
        4. Fixed action pattern: Motor program for behavior fig 59.3
    5. Behavior as a Response to Stimuli in the Environment
      1. Egg retrieval behavior requires perception of egg out of nest
        1. Convert light energy of photons to energy form of nervous system
        2. Visual input converted to electrical nerve impulse
      2. Animals must respond to other environmental stimuli
        1. Orient from food source back to nest, rely on sun position
        2. Finding a mate, use particular chemical scent
      3. Transduction
        1. Electromagnetic and light energies converted to nerve impulse energy
        2. Conversion of energy in environment to an action potential
        3. First step in processing information perceived by senses
      4. Example: Transduction of visual stimuli
        1. Rhodopsin made from cis-retinal and opsin protein
        2. Cis-retinal absorbs light energy, changes shape to trans-retinal
        3. In turn changes shape of opsin, starts cascade of molecular events
        4. Eventually triggers nerve impulse
      5. Sound, odor, taste also transduced to nerve impulses
  2. The Neural Basis of Behavior
    1. Perception of Environment Dependent on Sensory Systems
      1. Sensory structures are specific
        1. Hearing limited to certain frequencies
        2. Vision limited to certain wavelengths of light
        3. Smell dependent on certain chemicals in air or water
      2. Senses monitor environment with sensory neurons that detect specific stimuli
      3. Neuroethology: Study of neural basis of behavior
    2. Neuroethology in Action
      1. Example: Prey capture in frogs and toads
        1. Catches insects with sticky tongues
        2. Image of insect enters lens, focused on retina
          1. Light-sensitive cells in retina relay information about position fig 59.4
          2. With movement, image passes over different groups of cells
        3. Object size and movement are important
          1. Brain identifies insect as prey object
          2. Insect detector cells respond to sign stimulus (insect)
          3. Triggers releasing mechanism in brain
          4. Initiates fixed action pattern of ejecting tongue toward prey
      2. Example: Nudibranch escape response fig 59.6
        1. Model system, has simple nervous system, behaviors easy to record
        2. Mollusk nervous system has few, but large neurons
        3. Behavior occurs in response to presence of predator, sea star
          1. Response is alternating dorsal-ventral flexions of body
          2. Move animal through water
        4. Motor patterns associated with firing of three groups of neurons in brain
          1. Dorsal flexion neurons stimulate dorsal flexion muscles
          2. Ventral flexion neurons stimulate ventral flexion muscles
          3. Third neuron group causes alternation of impulse activity in other two groups
      3. Example: Cockroach air-sensitive mechanoreceptors
        1. Sensory hairs located on abdominal cerci
          1. Hairs moved by air microcurrents produced by approaching predator
          2. Sensory neurons generate impulses when hairs move
          3. Impulses conducted across single synapse
          4. Excite giant neuron, transmits impulses to ganglion in thorax
          5. Excite motor neurons that cause escape locomotion
        2. Response is extremely fast, 60 microseconds between detection and action
  3. Behavioral Genetics
    1. Studies Examine Genetic Basis for Behavior
      1. Example: Tryon's rat maze breeding experiments fig 59.5
        1. Rats trained to run a complex maze
        2. Maze-bright rats bred to each other, progeny were fast learners
        3. Maze-dull bred to each other, progeny were slow learners
        4. Ability to learn is genetically determined to some degree
        5. Intelligence related only to performance in that certain maze
        6. Fast learners may have advantage to increase survival and/or reproduction
      2. Example: Hybrid love-bird nesting experiments fig 59.6
        1. Two species differ in carrying materials used to build nest
          1. A. personata holds materials in beak
          2. A. roseicollis tucks materials under flank feathers
        2. Hybrids carry materials in intermediate manner, shift between two locations
        3. Similar hybrid intermediate behaviors in courtship songs of crickets, tree frogs
      3. Example: Mutant behavioral abnormalities in mice and Drosophila
        1. Three "personality" marker genes in mice
        2. Genetically engineered mice can't synthesize nitric oxide, show aggressive behavior
        3. Gene fosB associated with female mice nurturing of young
59.2 Comparative physiology focuses on how learning influences behavior
  1. Learning
    1. Psychology and the Study of Animal Behavior
      1. Examined by comparative psychologists
        1. Worked primarily on rats in laboratory settings
        2. Identified ways by which animals learn
      2. Learning is modification of behavior from experience not maturation
      3. Nonassociative learning
        1. No connection formed between stimulus and response
        2. Habituation
          1. Decrease in response with repeated stimulation
          2. Stimulus without reinforcement
          3. Initially evokes strong response, magnitude declines with repeated exposure
          4. Learning to not respond to a stimulus
          5. Example: Bird response to falling objects
        3. Sensitization
          1. Animal shows increased response with subsequent stimulation
          2. Opposite of habituation
      4. Associative learning fig 59.7
        1. Connection between two stimuli or between stimulus and response
        2. Behavior modified or conditioned through association
        3. More complex than habituation or sensitization
      5. Types of associative behavior
        1. Classical conditioning = Pavlovian conditioning
          1. Repeated presentation of stimulus in conjunction with response causes formation of
            association between them
          2. Example: Pavlov's dog salivation experiments
            1. Repetition of unconditioned stimulus (meat) associated with unconditioned response (salivation)
            2. Association made with unrelated repeated conditioned stimulus (bell)
            3. >
        2. Operant conditioning
          1. Reward or punishment follows only desired behavioral response
          2. Association must be made for reinforcing stimulus (reward/punishment) to occur
          3. Example: Skinner's conditioned rat experiments fig 59.8
            1. Rats learned to press a lever behavioral response) to obtain food (reward)
            2. Trial-and-error learning of importance to most vertebrates
        3. No longer thought that any stimulus can be conditioned in these ways
          1. Not true that any two stimuli can be linked in classical conditioning
          2. Not true that animals can be taught any behavior via operant conditioning
          3. Instinct guides learning, determines information learned by conditioning
    2. Instinct
      1. Some animals have innate predisposition to form certain associations
        1. Example: Rats, injury and food pellets
          1. Food pellets !’ x-rays (future injury) !’ remember taste, not size of pellet
          2. Food pellets !’ electric shock (immediate injury) !’ remember size, not taste
        2. Example: Pigeons
          1. Learn to associate color and food, but not sound and food
          2. Learn to associate sound and danger, but not color and danger
      2. Learning preparedness
        1. What can be learned is biologically influenced
        2. Learning possible within boundaries set by instincts
      3. Innate programs evolve since they support adaptive responses
        1. Rats forage at night, identify food by odor, not size or color
        2. Pigeon seeds have distinctive color to see, doesn't make sound to hear
      4. Study of learning expanded to include ecological significance
        1. Ecology is key to limit of what animal can learn
        2. Example: Clark's nutcracker and seed caches
          1. Store seeds when they are plentiful, eat during winter
          2. Thousands of caches buried and later recovered
          3. Birds expected to have excellent spatial memory fig 59.9
          4. Have large hippocampus, center for memory storage in the brain
  2. The Development of Behavior
    1. Behavior Has Genetic and Learned Components
      1. Ethology and psychology less polarized
      2. Both factors interact in development to shape behavior
    2. Parent Offspring Interactions
      1. Imprinting
        1. Animal forms social attachments during process of maturation
        2. Filial imprinting: Social attachment between parents and offspring
          1. Young birds follow mother within hours of hatching, bond forms
          2. Example: Lorenz imprinting with geese fig 59.10
          3. Other objects can be effective in imprinting as well fig 59.11
        3. Occurs during sensitive phase or critical period after birth
      2. Social interaction during critical period are needed to learn normal behavior
        1. Example: Harlow's monkey baby/surrogate mother experiments
        2. Orphaned baby monkeys form social attachments with cloth or wire mothers
      3. Physical contact needed for proper growth and well-being
        1. Deprivation results in abnormal development, future social behavior
        2. Constant mother figure needed for normal growth and development
      4. Biological need for parent-offspring interactions
        1. Female rats lick pups after birth
          1. Stimulation inhibits release of endorphin that blocks normal growth
          2. Licked pups have more brain receptors for glucocorticoid hormones
          3. Have longer-lived brain neurons,greater tolerance for stress
        2. Massaged premature babies gain weight rapidly
        3. Touch and contact important for physical and behavioral development
      5. Sexual imprinting
        1. Individual learns to direct sexual behavior at member of its own species
        2. Cross-fostering studies
          1. Individuals raised by another species
          2. Recognizes foster species as its own
          3. When sexually mature, will attempt to mate with foster species
    3. Interaction Between Instinct and Learning
      1. Interaction of instinct and experience develops behavior
      2. Example: Marler's courtship song experiments fig 59.12
        1. Song sung by mature males, is species-specific
        2. Control song young male hears, record song produced as adult
        3. Sang poorly as adult if no song or other species song when young
        4. Sang well with own song, even along with another species song when young
      3. Birds have genetic template, instinctive program, for song
        1. Template accepts correct song as model
        2. Song acquisition depends on learning, can learn only correct song
        3. Genetic template is selective
      4. Practice and experience needed to perfect song
        1. Bird deafened after learning its species song
        2. Still sings poorly due to lack of hearing self practice
      5. Recent contradictory research
        1. Male white-crowned sparrow caged next to another species male learned that species' song
        2. Social stimuli are important to override innate program
      6. Brood parasite bird songs are completely genetically set fig 59.13
        1. Males would hear song of foster species, not own species
        2. No correct song models available
  3. The Physiology of Behavior
    1. Many Internal Factors Influence Behavior
      1. Reproductive behaviors controlled by hormones
        1. Courtship behaviors occur only during breeding season
          1. Changes in day length triggers secretion of gonadotropin-releasing factors
          2. Stimulates release of gonadotropins FSH and LH by anterior pituitary
          3. Hormones cause development of reproductive tissues involved in breeding
          4. Also stimulate secretion of steroid sex hormones
          5. Act on brain to initiate behaviors associated with reproduction
        2. Hormones have organizational and activational effects
          1. Estrogen in male causes development of song system
          2. In mature male testosterone activates song
      2. Interaction among hormones, behavior and stimuli in physical and social environment
        1. Example: Lehrman's ring dove experiments fig 59.14
          1. Androgens stimulate male courtship behavior
          2. Male's behavior causes release of FSH in female
          3. FSH stimulates growth of ovaries, development of follicles
          4. Follicles release estrogen
          5. Estrogen initiates nest construction
          6. Nesting behavior stimulates release of progesterone
          7. Progesterone initiates incubating behavior in female and male
        2. Led to additional studies in behavioral endocrinology
        3. Example: Anole lizards
          1. Males begin courtship after seasonal rise in temperature
          2. Male courtship needed to stimulate follicle growth in female
      3. Reproductive behavior involves physical environment, behavior of mate and release of hormones
        1. Hormones are a proximate cause of behavior
        2. Must be released when conditions most favorable for growth of young
      4. Territoriality and dominance behavior have hormonal influences
        1. Hormones may interact with neurotransmitters
        2. Estrogen affects serotonin in mice, associated with mood swings in human females
  4. Behavioral Rhythms
    1. Animals Exhibit Behaviors Regularly Associated with Time
      1. Some behaviors coincide with lunar or tidal cycles fig 59.15
      2. Based on both endogenous (internal) rhythms and exogenous (external) timers
      3. Most behavioral rhythms are keyed to daily cycles
        1. Circadian rhythms occur at 24 hour intervals
        2. Have strong endogenous component, appear to be driven by biological clock
        3. Free-running rhythms: Occur at regular cycles even in absence of external cues
          1. Example: Fruit fly pupa hatch in morning
          2. Keep track of time with internal clock
          3. Pattern determined by single per gene
          4. Mutations shorten or lengthen daily rhythm
          5. Gene produces protein in brain in regular 24-hour cycle
          6. Serves as fly's pacemaker of activity, affects expression of other genes
          7. Accumulation of protein turns gene off
      4. External exogenous cues realign timing when biological clock does not match environmental clock
        1. Rhythm drifts out of phase without external cues
        2. Exposure to environmental cue resets clock, synchronizes behavior
        3. Light is most common cue in circadian rhythms
      5. Human sleep/activity pattern is example of circadian rhythm
        1. Timing averages 24 hours, varies significantly with individuals
        2. Day/night cycle resets free-running clock to 24 hour cycle
      6. Biological clock associated with optic lobe of brain
        1. Suprachiasmatic nuclei (SCN) in hypothalamus of mammals
          1. SCN is self-sustaining oscillator, spontaneous cyclic changes in activity
          2. Acts as pacemaker for circadian rhythms
          3. SCN influenced by light, direct and indirect neural projections from retina
        2. SCN regulates melatonin production by pineal gland
          1. More melatonin is secreted with short day length
          2. Variation in melatonin is an indicator of seasons
          3. May be associated with "jet lag" with day/night travel
      7. Circannual behaviors are cycles based on annual variations
        1. Include breeding, hibernation, migration
        2. Timed by hormonal and physiological changes
        3. Keyed to exogenous factors like day length

59.3 Communication is a key element of many animal behaviors

  1. Courtship
    1. Nature of Communication Signals
      1. Animals produce signals to communicate with potential mates
      2. Stimulus/response chain
        1. One behavior by one partner releases another behavior fig 59.16
    2. Courtship Signalling
      1. Stickleback fish behaviors
        1. Male attacks conspecific (same species) males approaching his nest
        2. Male recognizes competing male by red underside
          1. Shape and resemblance to fish unimportant
          2. Tinbergen constructed simple clay models
        3. Male recognizes female by egg-swollen abdomen
      2. Courtship signals are often species-specific
        1. Limit communication to a species, enhance reproductive isolation
        2. Example: Firefly flash patterns fig 59.17
          1. Females recognize conspecific males by flash pattern
          2. Males recognize conspecific females by flash response
          3. Reciprocal responses ensures species identity
      3. Visual courtship displays may have more than one component
        1. Example: Anolis lizards fig 59.18
          1. Movement: Extension of dewlap, pushup activity
          2. Color: Of dewlap
        2. Color may not be important in some anole species
    3. Pheromones
      1. Chemical communication between individuals of same species
        1. Human egg attracts sperm with chemicals
        2. Example: Silk moths
          1. Produce sex pheromone bombykol
          2. Male antennae have specific sensory receptors
          3. Receptors are extraordinarily sensitive
      2. Acoustical communication used to attract mate
        1. Example: Bullfrogs distinguish species-specific calls
        2. Example: Bird song identifies species and individual
    4. Levels of Specificity
      1. Level relates to function of signal
        1. Courtship signals are species-specific to reduce inviable hybrids
        2. Bird song is specific to allow his individual presence to be recognized
          1. Song and attacks used to establish territories
          2. Both are costly to continue once territories are established
          3. Lower energy costs by identifying selves to neighbors
        3. Mammals mark territory with pheromones
          1. Also signal individual identity
          2. Encoded as blend of chemicals
        4. Other signals are anonymous, don't convey identity of sender
          1. Include mobbing and alarm calls of birds
          2. Communicate presence of predator common to many species
  2. Communication in Social Groups
    1. Information Communicated Among Group Members
      1. Mammalian societies have guards that give alarm calls to warn of predators
      2. Social insects release alarm pheromones that trigger attack behavior
      3. Ants deposit trail pheromone between food and nest fig 59.19
      4. Honey bees exhibit complex dance language
    2. Dance Language of the Honeybee
      1. Honeybee colony composed of thousands of individuals
        1. Workers forage for miles around nest, collect nectar and pollen
        2. Switch between plant species depending on energy provided by plant
        3. Food sources occur in patches, exploited by entire colony
        4. Scout bees locate patches and communicate location to workers
      2. Communication via dance language
        1. Behavior pattern called waggle dance on vertical comb 54.20
        2. Path resembles figure-eight, waggles abdomen on straight part
        3. May stop to allow workers to taste sample of nectar
        4. Direction of food indicated
          1. Represent angle between food and hive in reference to sun
          2. Angle equals straight part of dance to vertical in hive
        5. Distance of food indicated by tempo, degree of vigor, of dance
      3. Dance language elucidated by use of robot bees
        1. Researchers completely control information of dance
        2. Determine location bees travel to
    3. Primate Language
      1. Animals vocalize to identify specific predators
        1. Vocalizations in vervet monkeys distinguishes eagles, leopards, snakes fig 59.21
        2. Chimpanzees, gorillas recognize and use symbols to communicate abstract concepts
        3. Human language is most complex
      2. Human languages are structurally similar
        1. Share basic similarities, same 40 consonant sounds
        2. May reflect how brains handle abstract information
        3. Shows a shared genetic characteristic
      3. Language in humans develops at an early age
        1. Infants recognize consonant sounds
        2. Adults rarely pronounce sounds not heard when young
        3. Go through neurally programmed babbling phase
        4. Children quickly learn vocabulary of thousands of words
        5. Next stage forms words into simple sentences that convey meaning
        6. Final stage composed of learning rules of grammar
      4. Non-verbal communication is also important
        1. Includes odor and body language
        2. Humans produce composite signals

59.4 Migratory behavior presents many puzzles

  1. Orientation and Migration
    1. Orientation
      1. Requires tracking stimuli in the environment
      2. Taxis: Movement towards or away from stimulus
        1. Flying insects are positively phototactic, attracted to light
        2. Cockroaches are negatively phototactic, avoid light
      3. Responses may not involve orientation, just change in activity
      4. Kinesis: Changes in activity levels that depend on stimulus intensity
    2. Migration
      1. Long-range, two-way movements
      2. Examples: Ducks, geese, monarch butterflies fig 59.22
        1. Butterflies migrate southward each August
        2. Return flight next spring, but with different individuals
        3. Two to five generations occur during flight north
      3. Patterns may be instinctive
        1. Changing patterns of bobolinks in new range
        2. New flight pattern to old range, then old flight pattern fig 59.23
    3. How Migrating Animals Navigate
      1. Migration orientation versus navigation
        1. Orientation: Simple ability to follow a bearing
        2. Navigation: Complex ability to set a bearing and then follow it fig 59.24
      2. Migrations achieved via navigation by sun and stars
        1. Some birds use sun as guide, reset and compensate for sun's movement by checking pole star position at night
        2. Other birds compensate for sun's movement via internal clock
      3. Many migrating birds use internal compass
        1. Have ability to detect earth's magnetic field
        2. Alter direction of movement with magnets
        3. Some possess magnetite in heads
      4. Birds first migration guided by celestial and magnetic cues
        1. Celestial cues dominate when the two give contradicting information
        2. Celestial cues inform birds to travel south
        3. Magnetic cues identify specific migratory pathway
      5. Turtle migrations may utilize ocean wave action as cue

59.5 To what degree animals "think" is a subject of lively dispute

  1. Animal Cognition
    1. Existence of Most Behaviors Are Anecdotal, Not Scientific
      1. Many researchers deny conscious though possible in animals
      2. Animal behaviors treated as though solely reflexive actions
    2. Animal Awareness fig 59.25
      1. Examples of cognitive thought
        1. Birds remove milk bottle foil caps
        2. Macaques wash sand from potatoes and grain
        3. Chimpanzees probe for termites with twigs
        4. Vervet monkeys identify predators with vocalizations
      2. Few experiments currently exist
        1. Some animals give false information to manipulate behavior of others
        2. Deception may occur in baboons and chimpanzees
        3. Difficult to field test this type of research
      3. Should not categorically deny the possibility of animal consciousness

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