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Chapter 51
Behavioral Biology
What is Behavior?
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Movement
Noise
Learning
Secretions
Behavior: what an animal does and how it
does it
Proximate and Ultimate Causes
• Proximate questions are mechanistic,
concerned with the environmental stimuli, if
any, that trigger a behavior, as well as the
genetic and physiological mechanisms
underlying a behavioral act
• Ultimate questions address the evolutionary
significance of a behavior
Proximate and Ultimate Causes
• Ex: Magnolia warbler breeds in spring and
early summer
– Proximate: breeding is triggered by the effect of
increased day length on an animal’s
photoreceptors
– Ultimate: why did natural selection favor this
behavior and not a different one?
Nature Versus Nurture
• It is not an “either-or” debate
• It includes both when it comes to behavior
• There have been genes linked to certain behavior
– Dg2 gene in fruit flies
• Gene influences the level of a protein that functions in signaling
within cells
– One allele causes low levels of the protein, and the fly is lazy
– One allele causes high levels of the protein, and the fly buzzes
around like crazy
– Genetic claims for human behaviors is still being
investigated
Innate Behavior
• Developmentally fixed
• Behaviors that are genetically programmed
without any environmental influence
– All individuals exhibit virtually the same behavior
despite environmental differences within and
outside their bodies during development and
throughout life
• Ex: blind newborn birds open their mouths
and chirp to get parents to feed them
Ethology
• Originated in the 1930’s with naturalists that
tried to understand how a variety of animals
behave in their natural habitat
– Was the “mother” of modern behavioral biology
• von Frisch, Lorenz, Tinbergen won Nobel Prize
in 1973
– Focused on proximate mechanisms, but with an
eye toward the genetic links to behavior and the
adaptive nature of behavior
Ethology
• Fixed Action Pattern (FAP): a sequence of behavioral
acts that is essentially unchangeable and usually
carried to completion once initiated
– Triggered by an external sensory stimulus known as a sign
stimulus
• Usually some feature of another species
– Some moths fold their wings and drop instantly in response to the
ultrasonic signals sent out by predatory bats
– Male Three-Spined Stickleback Fish: attacks other males that invades
its territory just at the sight of the red belly of the intruder
» Can fish using red lures
» Red triggers either aggressive or sexual behavior in many
species that have color vision
– Mayflies swarm and mate on the water surface and detect the water
by the light reflected from it
» Roads can produce the same reflection
– FAP’s triggered by simple cues prevent an animal from
wasting time processing or integrating a wide variety of
inputs
Behavioral Ecology
• Research field that views behavior as an
evolutionary adaptation to the natural
ecological conditions of animals
• Natural selection will favor behavioral patterns
that enhance survival and reproductive
success
Behavioral Ecology
• Songbird Repertoires
– Many songbirds have a repertoire of songs that
are different across species
– Increases fitness because the older a male gets,
the more songs he knows and females prefer
males with more tunes to sing
• So they don’t get too bored
Behavioral Ecology
• Cost-Benefit Analysis of Foraging Behavior
– Natural selection refines behaviors that enhance
the efficiency of feeding
– Food obtaining behaviors include recognizing,
searching for, capturing, and eating food
• Foraging encompasses all of these behaviors
– Optimal foraging theory views foraging behavior
as a compromise between feeding costs and
feeding benefits
– Crow Experiment
• Opportunistic feeders that avail themselves a variety of
foods
• In British Columbia (where they did the experiment)
crows pick up crustaceans off the beach with their
beak, fly upward and drop them on a rock to break
their shells and will continue until the shell breaks
– The higher they fly, the less they have to retry
» Energy Cost
• Predicted the crow would fly to a height that provided
the most food relative to the amount of total energy
required to break the shell
– Prediction was proven true
– Bluegill Sunfish Experiment
• Feed on Daphnia, generally selecting larger individuals
that provide the most energy
• Smaller prey will be selected if larger prey is too far
away
• Predicts that the proportion of small to large prey eaten
will also vary with the overall density of prey
– Foraging behavior tends to minimize the risk of
the predator becoming prey while foraging
Learning
• Modification of behavior resulting from specific experiences
• Most innate behaviors improve with performance as animals
learn to carry them out more efficiently
• Ex: Alarm calls of vervet monkeys
– Give distinct alarms when they see leopards (bark), eagles (doublecough), or snakes (chutter)
– Behave in the appropriate way depending on the call
– Infant’s calls are indiscriminate, give an “eagle call” when they see any
bird
– As adults, they only give a call when they see one of two species of
eagles that are proven vervet eaters
– Social confirmation speeds up the process
– Have the innate behavior to make a call upon seeing danger, but learn
to fine-tune it with age
Learning versus Maturation
• Maturation: ongoing developmental changes
in neuromuscular systems
– We think of birds “learning to fly” but some have
been raised in an environment where they could
not flap their wings, and then when they reached
an age where flying is normal, they picked it up
immediately
Habituation
• Simple type of learning that involves a loss of
responsiveness to stimuli that convey little or
not information
– Hydra retracts upon touch, but stops responding
to repeated stimuli
– “Little Boy Who Cried Wolf”
• May increase fitness by allowing an animals’
nervous system to focus on stimuli that signal
food, mates, or real danger instead of wasting
time or energy on other irrelevant stimuli
Imprinting
• Learning that is limited to a specific time period in an
animals life and that is generally irreversible
• Mother-offspring bonding: if bonding fails to happen,
the parent will not initiate care of the infant
• Lorenz’s Geese Experiment
– Half a clutch with mother and half with Lorenz
• Lorenz’s clutch showed no recognition to mother or others of the
same species
– Some initiated courtship with humans as adults
– Imprinting stimulus
• Found that anything that moved, and especially made sound was
“Mother”
– A ticking clock was once used to imprint on
Imprinting
• Sensitive Period: a limited phase in an animal’s
development when learning of particular behaviors
can take place
– Geese imprinting is the first 2 days of life
– Young birds must imprint to know parents, and parents
must imprint to know young
– Two species of finches were reared separately and initially
imprinted with their own species (first sensitive period)
• When they were becoming sexually mature, they were put with
members of the opposite species and sexually imprinted on them
(second period)
• Were placed back with their own species and were reluctant to
mate, but when placed with other species they mated, even if it
was up to 8 years since they had seen the other species
Bird Song
• First 50 days they just listen to others’ songs
and form a template
• Sings tentative notes called a subsong
– Hears its own singing and compares it to others
and modifies it as needed
• It then crystallizes its adult song
Human Sensitive Periods
• Foreign languages are learned most easily up
until the teen years
Learn to Associate
• Associative Learning: ability of many animals
to learn to associate one stimulus with
another
– Pavlov
• Classical conditioning: involves learning to associate an
arbitrary stimulus with a reward or punishment
• Operant Conditioning: trial-and-error learning
– Learns to associate one of its own behaviors with
a reward or punishment and then tends to repeat
or avoid that behavior
– Skinner
• Mouse and lever
Playing
• No apparent internal goal but involves movements
closely related to goal-directed behaviors
– Stalk-and-attack playing
• The “Practice-Hypothesis” suggests that play is a
type of learning that allows animals to perfect
behaviors needed in functional circumstances
• The “Exercise Hypothesis” suggests that play is
adaptive because it keeps the muscular and
cardiovascular systems in top condition
Animal Cognition
• Cognition: ability of an animal’s nervous
system to perceive, store, process, and use
information gathered by sensory receptors
• Cognitive ethology: examines the connection
between an animals’ nervous system and its
behavior
– Animal consciousness and awareness
– What calculations does a dog make to determine
where a Frisbee will land?
Kinesis and Taxis
• Kinesis: simple change in activity or turning
rate in response to a stimulus
– Roly Polies become more active in dry areas and
less active in humid areas, a behavior that keeps
these in moist environments
• Don’t move toward or away, buy slow down in
favorable environments
• Taxis: automatic, oriented movement toward
or away from some stimulus
Use of Landmarks
• Go towards a stimulus that is an arbitrary
landmark the animal must learn
• Honeybees:
– Keep track of the nectar supplies from their local
flowers and concentrate their foraging on the
flowers that are most nectar-rich
• Use landmarks along the way
• Know where they are going and make a “bee-line”
because they learned certain landmarks as young
Migration Behavior
• Migration: regular movement over relatively
long distances
• Generally make one round trip between two
regions each year
• Notable examples: birds, whales, butterflies,
and oceangoing fish
– Golden Plover: from arctic breeding grounds to
South America, or even Hawaii
• Use one of three mechanisms:
1. Piloting: animal moves from one familiar landmark
to another until it reaches its destination
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Short-distance migrations
2. Orientation: detects compass directions and
travels in a particular straight line path for a certain
distance until it reaches its destination
3. Navigation: animal determines its present location
relative to other locations in addition to detecting
compass direction
• Cues:
– Earth’s magnetic field
– Sun
– Star
• Some fix on the North Star or use an internal
clock
Social Behavior
• Social Behavior: any kind of interaction
between two or more animals, usually of the
same species
– Most sexually reproducing species must be social
for part of their life cycle in order to reproduce
• Sociobiology: applies evolutionary theory to
the study and interpretation of social behavior
Competitive Social Behaviors
• Sometimes involves cooperation, as when a
group carries out behavior more efficiently
than is possible for a single individual
• Although they may be cooperating, each
individual acts in a way that will maximize its
own benefits, even if this is at a cost to the
other participant
Agonistic Behavior
• A contest involving both threatening and submissive behavior
determines which competitor gains access to some resource
• Sometimes involves a test of strength, more often the engage
in threat displays that make them look large and fierce
– Severity depends on the amount, type, and availability of
the resource
• Male ground squirrels kill others for females because
they are only in heat for a few hours each year
• Usually only occurs with individuals of the same species, and
can be completely symbolic in nature
• Reconciliation Behavior: a kind of friendly
relation between the conflicting individuals
following the conflict itself
Dominance Hierarchies
• Chickens that are unfamiliar with each other
will sit and peck at each other until the clear
dominant one is found
– Pecking Order
Territoriality
• Territory: an area that an individual defends,
usually excluding other members of its own
species
• Typically used for feeding, mating, and rearing
young
• Established and defended by agnostic
behavior
• Range in size from very large (hundreds of
square kilometers) to very small
Courtship
• Behavior patterns that lead up to copulation
or gamete release
• Consists of a series of displays and
movements, either by the male, female, or
both
• Enables animals to identify potential mates of
the same species
Parental Investment
• The time and resources an individual must
spend to produce and nurture offspring
• The mate who has the highest parental
investment is generally the more choosy of
the two when it comes to picking a mate
Mating Systems
• Promiscuous: no strong pair-bonds or lasting
relationships
• Monogamous: one male mating with one
female
• Polygamous: an individual of one sex mating
with several of the other sex
– Most often one male and several females
• Polygyny
– Sometimes it is one female and several males
• Polyandry
• Parental investment has a lot to do with
mating systems
– Birds who need a lot of attention require both
parents foraging for food for them
• Monogamy
– Animals who are relatively independent from birth
can make it on their own
• Polygamy
Defining Signals and Communication
• Signal: behavior that causes a change in
behavior in another animal
• Transmission of, reception of, and response to
signals makes up communication
– Visual, auditory, chemical, tactile, and electrical
signals
Pheromones
• Odors emit chemical signals for
communication
– Trail of Ants
• Bees
http://youtu.be/-7ijI-g4jHg
– Maintain the social order of honeybee colonies
– Convey the location of good food sources
– Dances
• Tells what and where new food resources are, and how
far away
Nature is Selfish
• Most animals act in a way that benefits them, and
they do not care if it harms others
• Altruism: unselfish behavior
– Reduce their individual fitness and increase the fitness of
the recipient of the behavior
– Ex: Belding Ground Squirrel’s cry
– Ex: bee societies where workers are sterile and sting
intruders
– Ex: Mole Rat colonies have one reproducing female who
mates with three males
Inclusive Fitness
• Describes the total effect an individual has on
proliferating its genes by producing its own
offspring and by providing aid that enables
other close relatives to increase the
production of their offspring
– Prairie Dogs
Hamilton’s Rule
• Benefit to the recipient (B)
• Cost to the altruist (C)
• Coefficient of relatedness (r)
– Equals the probability that a particular gene present in one
individual will also be inherited from a common parent or
ancestor in a second individual
• B is the average number of EXTRA offspring that the
beneficiary of an altruistic act produces
• C is the average number of FEWER offspring the
altruist produces
• For natural selection to favor an altruistic act,
the benefit to the recipient multiplied by the
coefficient of relatedness must exceed the
cost to the altruist
• Kin selection: natural selection that favors
altruistic behavior by enhancing reproductive
success of relatives