Chapter 51

CHAPTER 51
BEHAVIORAL BIOLOGY
Lecture Outline
• Proximate and ultimate causes of behavior
• Genes and Environmental factors
• Innate Behavior
• Classical Ethology
• Behavioral Ecology
• Learning
• Experience-based modification of behavior
• The bird song model and other examples
• Animal cognition
• Social behavior and sociobiology

What is Behavior?
• activities that an organism undertakes during life processes
• muscular or non-muscular
• motions
• songs
• secretion of hormones
• marking territory

Questions in behavioral biology
What? How? Why?
• Proximate questions
- mechanistic
- concerned with the environmental stimuli that trigger a behavior
- concerned with the underlying genetic and physiological mechanisms

Questions in behavioral biology
What? How? Why?
• Ultimate questions
- address the evolutionary significance for a behavior
and why natural selection favors this behavior

--> proximate and ultimate causes are related

Nature or nurture?
-->
• In biology, the nature-versus-nurture issue is not about whether genes or environment influence behavior, but that both are involved.

Fig. 51.1 Case study: nest-building behavior in lovebirds

Innate behavior
• innate behavior is …
• occurs due to …
• environmental differences among individuals does not appear to alter the behavior

Classical ethology
Ethology = …

• Karl von Frisch
• Konrad Lorenz
• Niko Tinbergen

- focused on proximate mechanisms
- suggested links to genetic mechanisms and adaptation
- presaged an evolutionary approach to behavioral biology

Fig. 51.2 Nico Tinbergen’s experiments about use of landmarks in wasps

• Fixed action pattern (FAP)
= …

• FAP is triggered by an external sensory stimulus known as a sign stimulus
• FAP usually occurs in a series of actions the same way every time
• many animals tend to use a relatively small subset of the sensory information available to them and behave stereotypically

Fig. 51.3 Innate behavior of male three-spined stickleback fish

Behavioral ecology
-- >
• Behavioral ecology:
views behavior as an evolutionary adaptation to the natural ecological conditions of animals

• animals behave in ways that maximize their fitness
• genes influence behavior

Behavioral ecology: examples
• song bird repertoires:
• many birds have multiple-song repertoires

• cost-benefit analysis of foraging behavior:
• foraging is …
• optimal foraging theory:
--> natural selection will benefit animals …

• Example crows: energy required to break mollusk shells?

Learning
= …
• Learning is the modification of behavior resulting from specific experiences
e.g. human language
alarm calls
predator avoidance

• Learning versus maturation
• Maturation: a behavior may improve because of ongoing developmental changes in neuromuscular systems
• e.g. flight in birds

• Habituation: loss of responsiveness to unimportant stimuli or stimuli that do not provide appropriate feedback
• e.g. animals stop responding to ‘false alarm’
--> saves energy & nerves

• Imprinting:
= recognition, response, and attachment of young to a particular adult or object
--> imprinting is …

The bird song model
-- > ...
• two kinds of bird-song development:

Associative learning
= …
• Classical conditioning: learning to associate an arbitrary stimulus with a reward or punishment
• ring a bell upon feeding repeatedly ? dogs may begin to salivate without food being present
• Operant Conditioning:
= …
• associations of
own behavior with
reward or punishment
e.g. animal training

Play
• common among mammals and birds
• no apparent external goal
• may facilitate social development or practice of certain behaviors and provide exercise

Animal cognition
= …
• Cognition = ability of an
animal’s nervous system to
perceive, store, process, and
use information gathered
by sensory receptors

--> the study of cognition connects nervous system function with behavior

Cognitive mechanisms
• Kinesis = change in activity rate in response to
a stimulus

• Taxis = automatic, oriented movement to or
away from a stimulus

• phototaxis
• chemotaxis
• geotaxis

Use of landmarks within a familiar area:
landmark = a recognized object or environmental cue
--> used to …

• Cognitive maps:
= internal codes of spatial relationships of objects in the environment
--> used to …

Figure 51.14 Electronic surveillance of honeybees

• Migration Behavior:
Migration = …

Piloting: an animal
moves from one
familiar landmark
to another until it
reaches its destination.

• Orientation: animals can detect directions and travel in particular paths until reaching destination
• Navigation involves determining one’s present location relative to other locations in
addition to detecting
compass directions
cues used:
- earth’s magnetic field
- sun
- stars

Consciousness and science
• Are nonhuman animals consciously aware of themselves and their surroundings?
• Do animals behave in ways we associate with conscious processing?

-->many scientists feel
there is no way to
answer such questions
scientifically

Social behavior
= …
• Individuals within a population usually have a common niche and experience limiting resources

• Cooperative behavior:
allows a group to carry
out an activity more
efficiently

• Agonistic behavior is a contest involving threats:
• submissive behavior
• ritual = the use of symbolic activity
• generally, no harm is done
--> one individual will …
(mates, food, space)

• Reconciliation behavior:
happens between conflicting individuals in animals that live in rather stable social groups

• Dominance hierarchies:
involve a ranking of individuals in a group
-->“pecking order”
• alpha dominates over beta, beta over all others
• alpha organisms control the behavior of others

--> resources are distributed according to rank

examples:

• Territoriality: behavior where an individual defends a particular area, called the territory
• territories for feeding, mating, and rearing young
• are fixed in location
• marked by singing, spraying, aggressive behavior
--> disadvantage: …

Figure 51.22 Staking out territory with chemical markers

Reproductive behavior
• Courtship behavior:
- consists of behavior patterns that lead to copulation
or external fertilization
- includes a series of displays and movements by the
male or female
--> dual purpose:
- …
- …

Figure 51.23 Courtship behavior in the three-spined stickleback

• Mating systems:
--> differ considerably among species
• …………………….: no strong pair bonds between males and females
• ……………………: longer term relationship; a male and a female maintain a pairing
• ……………………: an individual of one sex mating with several of the other sex
Polygyny is a specific example of polygamy, where a single male mates with many females.
Polyandry occurs in some species where one female mates with several males (honeybee queen mates with several drones)

• Mate choice: females are usually more discriminating
-->……………………………………………. (i.e. better genes)

• Parental investment: refers to the time and resources expended for raising of offspring
• generally lower in males --> …
• females invest more time & energy --> …

Social interactions & communication
• Signal: behavior that causes a change in the behavior of another animal
• Communication: transmission of, reception of, and response to signals
• Examples:
- displays such as …
- transmission of information by …

• Pheromones: chemicals released by an individual that bring about mating and other behaviors in individuals of the same species
--> chemical communication
• e.g. most insects (bees, ants, moths …)
• many vertebrates

• The Dance of the
Honeybee:
• bees forage to maximize their food intake
• successful individual will communicate
the location to other bees through a dance

Altruistic behavior
• Altruism: …

• Alarm calls
- identify the location of the individual
- warns others of the same species within earshot

Altruistic behavior
• Honeybee societies:
• one queen --> offspring
• thousands of sterile workers

• Naked mole rat colonies:
• only one reproductive female (‘queen’)
• up to 250 nonreproductive males and females

-- > …

WHY ??

Inclusive Fitness
• How can a naked mole rat or a worker bee enhance its fitness by helping other members of the colony?
--> if related individuals help each other, …
--> inclusive fitness is defined as …

--> relatedness must be high for this to be beneficial

Darwinian fitness: contribution an individual makes to the gene pool of the next generation, measured as production of fertile offspring

Hamilton’s Rule and kin selection
• Hamilton’s rule: for natural selection to favor an altruistic act, the benefit (reproduction) x the coefficient of relatedness must exceed the cost
rB > C
r = relatedness
B = benefit to recipient
C = cost to the altruist
-- > …..

• Example:
Two brothers are surfing, one is drowning; the other dives in to save him
cost: 5 % chance to drown x two lost offspring
C = 0.05 x 2 = 0.1
relatedness: r = 0.5
potential benefit: ~2 potential children per brother
rB = 0.5 x 2 = 1
C = 0.1
--> in this case altruistic behavior is favored

Kin Selection
• Kin selection: …

--> animals that show ‘unselfish’ behavior are often closely related

Key terms 51
Behavior
Ethology
Fixed action pattern (FAP)
Sign stimulus
Behavioral ecology
Foraging
Optimal foraging theory
Learning
Maturation
Habituation
Imprinting
Sensitive period
Associative learning
Classical conditioning
Operant conditioning
play
cognition
cognitive ethology
kinesis
taxis
landmark
migration
cognitive map
social behavior
agonistic behavior
ritual
dominance hierarchy
territory
courtship
reconciliation behavior
parental investment
promiscuous
monogamous
polygamous
polygyny
polyandry
signal
communication
pheromone
altruism
inclusive fitness
coefficient of relatedness
Hamilton’s rule
kin selection