Behavioral Biology

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Behavioral Biology

• Chapter 52
• Biology Raven and Johnson 7th Ed.

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Outline

• Behavioral Genetics
• Learning
• The Development of Behavior
• Animal Cognition
• Migratory Behavior
• Courtship
• Communication in Social Groups

• Behavioral Ecology
• Foraging Behavior
• Territorial Behavior
• Reproductive Strategies
• Sexual Selection
• Mating Systems
• Altruism
• Kin Selection
• Social Systems

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Approaches to the Study of Behavior

• Behavior can be defined as the way an organism
  responds to stimuli in its environment.

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Behavioral Genetics

• Recent studies have shown identical human twins,
  separated at birth, develop many similarities,
  even though they were raised in very different
  environments.
• Behavior may be controlled by one, or many, genes.

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Learning Influences Behavior

• Comparative psychologists focus on learning as
  the major element that shapes behavior.
• nonassociative learning
• Animal is not required to form association
  between a stimulus and a response.
• examples
• habituation - decrease in response to a repeated
  stimulus with no positive or negative
  consequences
• sensitization - increased responsiveness to a
  stimulus

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Learning

• Associative learning
• Association between two stimuli or between a
  stimulus and a response.
• Classical conditioning - Paired presentation of
  two different stimuli creates an association
  between the stimuli (Pavlovian conditioning).
• Operant conditioning - Animal learns to associate
  its behavioral response with a reward or
  punishment.
• trial and error
• Skinner Box- mice learn to push a lever to
  release food.
• (They will push a lever to get cocaine and
  ignore food, sex, and play, until they die.)

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Learning

• Instinct
• Investigations have shown some animals have
  innate predispositions toward forming certain
  associations.
• Learning preparedness demonstrates that what an
  animal can learn is biologically influenced.
• An animals ecology is key to understanding what
  an animal is capable of learning.

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The Development of Behavior

• Parent-offspring interactions
• imprinting - social attachments to other
  individuals that will influence behavior later in
  life (Konrad Lorenz)
• sensitive phase or critical period

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Fig. 52.09
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The Development of Behavior

• Interaction between instinct and learning
• Genetic templates may guide young birds to learn
  appropriate song.
• During critical period, the template will accept
  the correct song as a model.
• Template is selective, and leaning plays a role.

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Animal Cognition

• What does thinking mean?

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Animal Cognition

• Central question in animal behavior is whether
  animals show cognitive behavior.
• Do they process information and respond in a
  manner that suggests thinking ?
• Some examples are compelling
• chimpanzees
• ravens

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Fig. 52.15
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Orientation and Migration

• Taxis - movement toward or away from a stimulus
• positive (toward) and negative (away)
• Kineses - increase in general activity level due
  to increased stimulus intensity
• Migrations - long-range, two-way movements
• monarch butterflies

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Orientation and Migration

• Navigation
• navigation - ability to set or adjust a bearing
  and follow it
• orientation - ability to follow a bearing
• Inexperienced starlings appear to migrate by
  orientation, while older birds use true
  navigation.
• magnetic field
• celestial clues

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Courtship

• Stimulus - response chain in which behavior of
  one individual in turn releases behavior of
  another individual
• Courtship signaling
• Signals are often species-specific .
• Reciprocal responses provide a continuous check
  on species identity.
• Stickleback- see next slide

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Stimulus-Response Chain
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Courtship

• Pheromones and acoustic signals
• Pheromones are chemical messengers used for
  communication between individuals, and often
  serve as sex attractants. (in humans egg and
  spermthey are from two individuals, right?)
• Silk moths are the most famous example.
• Many insects, amphibians, and birds produce
  species-specific acoustic signals to attract
  mates.

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Communication in Social Groups

• Communicated information
• alarm calls
• alarm pheromones
• trail pheromones
• dance language
• Waggle dance of European honeybee relays
  direction and distance of a located food source.
• primate vocalizations

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Waggle Dance of Honeybees
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Behavioral Ecology

• Behavioral ecology is the study of how natural
  selection shapes behavior.
• examines adaptive significance and survival value
  of behavior
• effect on fitness

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Foraging Behavior

• Optimal foraging theory - Natural selection
  favors individuals feeding on prey that maximize
  net energy intake efficiency.
• two assumptions
• Natural selection will only favor behavior
  maximizing energy acquisition if increased energy
  reserves lead to increases in reproductive
  success.
• Optimal foraging has resulted from natural
  selection.

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Territorial Behavior

• Territoriality is behavior in which individual
  members of a species maintain exclusive use of an
  area containing a limited resource.
• defense against intrusion
• made on costbenefit basis centered around fitness

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Competition for Space
6 birds species removed (R) were replaced by
existing species and by 4 new species (N).
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Parental Investment and Mate Choice

• Mate choice occurs when individuals do not mate
  at random, but appear to make decisions on mates
  base on quality.
• common in females, usually they have a larger
  reproductive investment
• Parental investment refers to contributions each
  sex makes in producing and rearing offspring.
• usually higher in females
• In mormon crickets, the male invests in a high
  energy sperm, and the males are more selective.

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Reproductive Competition and Sexual Selection

• Sexual selection occurs when individuals compete
  for mating opportunities.
• involves both intrasexual and intersexual
  selection
• leads to evolution of secondary sexual
  characteristics

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Products of Sexual Selection
In many species, the boys dress up for the girls
)
a. African paradise whydah b. Peacock c.
Eyespots/ Mates
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Reproductive Competition and Sexual Selection

• Intrasexual selection
• Individuals of one sex compete for the
  opportunity to mate with individuals of the other
  sex.
• Selection will strongly favor sexual dimorphism.
• sperm competition

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Intersexual Selection

• Intersexual selection
• benefits of mate choice
• Males may help rear young, gather food, defend
  nest, etc..
• Indirect benefits
• Females may choose healthiest or oldest males.
• overall genetic or physiological health
• more vigorous offspring

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Intersexual Selection

• Handicap hypothesis
• Only genetically-superior males can survive with
  a handicap.
• Sensory exploitation involves evolution in males
  of an attractive signal that exploits preexisting
  biases.

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Mating Systems

• Number of mates
• monogamy - one male and one female
• polygyny - one male and many females
• polyandry - one female and several males
• Needs of offspring
• altricial - require extensive, prolonged care
  (ex. Humans)
• precocial - require little parental care

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Mating Systems

• Extra-pair copulations -- (cheating)
• Researchers found that in one study, 20 of
  red-winged blackbird offspring were a result of
  extra-pair copulations.
• may be very pervasive
• Males benefit by increased mating success.
• Females may benefit by increased rearing
  assistance.

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Factors Favoring Altruism and Group Learning

• Altruism - performance of an action that benefits
  another individual at a cost to the actor (nest
  helpers)
• Natural selection would seem to argue against
  altruism.
• Such acts may not be truly altruistic, and may be
  benefiting the actor.
• Nest helpers may gain parenting experience or
  inherit territory.

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Factors Favoring Altruism and Group Learning

• Reciprocity - Individuals may form partnerships
  in which mutual exchanges of altruistic acts
  occur. Ex Vampire bats will share blood with
  those who have shared with them in the past.
• Kin selection - By directing aid toward close
  genetic relatives, an altruist may increase
  reproductive success of its relatives enough to
  compensate for the reduction in its own fitness.
• The more closely related the individuals, the
  more likely the potential genetic gain.

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Altruism

• Hamiltons Rule- Altruistic acts (acts that
  benefit another member of the same species) are
  favored when rb gt c
• r relatedness proportion of shared alleles
• b benefit
• c cost

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Examples of Kin Selection

• Beldings ground squirrel
• sound alarm calls when spot predators
• Females are more likely to call than males
  because colony is mostly her relatives.

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Group Living - Evolution of Social Systems

• Society - group of organisms of the same species
  organized in a cooperative manner
• Insects
• All ants, some bees, some wasps, and all termites
  are eusocial.
• Eusocial colonies are composed of different
  castes of workers that differ in size and
  morphology and have different tasks to perform.

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Vertebrate Societies

• Vertebrate social groups are usually less rigidly
  organized and cohesive.
• Some complex systems exhibit both reciprocity and
  kin-selected altruism.
• also display higher levels of conflict and
  aggression among group members

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Summary

• Behavioral Genetics
• Learning
• The Development of Behavior
• Animal Cognition
• Migratory Behavior
• Courtship
• Communication in Social Groups

• Behavioral Ecology
• Foraging Behavior
• Territorial Behavior
• Reproductive Strategies
• Sexual Selection
• Mating Systems
• Altruism
• Kin Selection
• Social Systems

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