Transcript Behavior

The Living World
Fifth Edition
George B. Johnson
Jonathan B. Losos
Chapter 39
Behavior and the Environment
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
39.1 Approaches to the Study of
Behavior
• Behavior can be defined as the way an
animal responds to stimuli in its
environment
 proximate causation deals with how the
behavior works
• the field of psychology often focuses on this
 ultimate causation deals with why the
behavior evolved
• the field of ethology (evolutionary behavior)
typically focuses on this
Figure 39.1 Two ways to look at a
behavior
39.1 Approaches to the Study of
Behavior
• The study of behavior has a long history of
controversy
 one issue has been the question of whether
an animal’s behavior is determined more by
an individual’s genes, or by its learning and
experience
 in other words, is behavior the result of nature
(instinct) or nurture (learning)?
39.2 Instinctive Behavioral Patterns
• Ethology is the study of animal behavior in
natural conditions
 ethologists study the instinctive nature of animal
behavior
 behavior in animals is often stereotyped and based
on preset paths in the nervous system
• the trigger for the behavior is a sign stimulus
• the animal responds to this stimulus via the innate releasing
mechanisms that provides the neural instructions
• the response is called the fixed action pattern
Figure 39.2 Sign stimulus and fixed
action pattern
39.3 Genetic Effects on Behavior
• Many animal behaviors are strongly
influenced by genes passed from parent to
offspring
 behavioral genetics investigates the
inheritance of genes connected to behavior
• for example, identical twins reared in different
environments show many similarities, indicating
that genes play a key role in determining human
behavior
39.3 Genetic Effects on Behavior
• In mice, the fosB
gene determines
whether or not female
mice will nurture
young
• When a female lacks
the fosB allele, she
will ignore her
newborn babies
Figure 39.3 A gene alters maternal care
39.4 How Animals Learn
• In many cases, animals alter their behavior as a
result of previous experiences
 this is called learning
• nonassociative learning
– this is the simplest type of learning
– it does not require an animal to form associations between two
stimuli or between a stimulus and a response
» sensitization occurs when repeating a stimulus produces
a greater response
» habituation is a decreased response to a repeated
stimulus
39.4 How Animals Learn
• Associative learning is a form of learning
in which behavior is modified, or
conditioned, because of an association
 classical conditioning occurs when paired
stimuli are presented, causing the animal to
form an association between the stimuli
• for example, Ivan Pavlov’s work with dogs
– unconditioned stimulus is meat powder, which
produces salivating
– conditioned stimulus is the sound of a bell, which the
dog associates with the meat powder
39.4 How Animals Learn
• Operant conditioning is a form of
learning in which an animal learns to
associate its behavioral response with a
reward or punishment
 B. F. Skinner’s worked with rats exposed to an
experimental cage called a “Skinner box”
• the rats learned through trial-and-error to depress
a lever in order to be fed
39.4 How Animals Learn
• As an animal matures, it may form
preferences or social attachments to other
individuals
 this process is called imprinting and is
sometimes considered a type of learning
• in filial imprinting, social attachments form
between parents and offspring
– for example, young birds of some species begin to follow
their mother or the first object they see after hatching
Figure 39.4 An unlikely parent
39.5 Instinct and Learning Interact
to Determine Behavior
• Some animals have innate predispositions
toward forming certain associations
 learning preparedness means that learning
is only possible within the boundaries set by
instinct
 for example, song development in birds is
based on a genetic template that guides
learning the appropriate song
• only the song of the correct species can be learned
Figure 39.5 Song development in birds
involves both instinct and learning
39.6 Animal Cognition
• In recent years, serious attention has been
given by researchers to the topic of animal
awareness
 do animals other than humans show
cognitive behavior—that is, do the process
information and respond in a manner that
suggesting thinking?
• for example, problem solving
Figure 39.6 Problem solving by a
raven
39.7 Behavioral Ecology
• The investigation of animal behavior can
be conveniently divided into three areas
 the study of its development
 the study of its physiological basis
 the study of its function
• Behavioral ecology is the study of how
natural selection shapes behavior
Figure 39.7 The adaptive value of
eggshell removal
39.8 A Cost-Benefit Analysis of
Behavior
• Behavioral ecologists examine the
evolutionary advantage of behavior by
asking if it provides an evolutionary benefit
greater than its cost
• Optimal foraging theory predicts that
animals will select food items that
maximize their net energy intake per unit
of foraging time
39.8 A Cost-Benefit Analysis of
Behavior
• Territoriality is a behavior in which an
individual defends a portion of its home
range and uses it exclusively
 territories are defended by displays that
advertise that the territories are occupied and
by overt aggression
 the adaptive value of territoriality depends on
the trade-off between the benefits and the
costs
Figure 39.8 The benefit of territoriality
39.9 Migratory Behavior
• Many animals breed in one part of the
world and spend the rest of the year in
another
 migrations are long-range two-way annual
movements
• compass sense is an innate ability to move in a
particular direction or bearing
• map sense is learned ability to adjust a bearing
depending on the animal’s location
Figure 39.9 Starlings learn how
to navigate
39.10 Reproductive Behaviors
• Sexual selection is competition for mating
opportunities
 intrasexual selection
• occurs between members of the same sex
• leads to the evolution of structures used in combat,
such as antlers
 intersexual selection
• is also called mate choice and occurs between
members of the opposite sex
• leads to the evolution of complex courtship
behaviors and of ornaments
Figure 39.10 The male peacock’s
feather is a product of sexual selection
39.10 Reproductive Behaviors
• The mating system is the typical number
of mates an animal has during its breeding
season
 monogamy is when one male mates with one
female
 polygyny is when one males mates with
more than one female
 polyandry is when one female mates with
more than one male
39.11 Communication Within Social
Groups
• In animals living in groups, information is
communicated between group members
 alarm call is given by an animal acting as a
“guard” and warns the group of a predator
 alarm pheromone is secreted by social
insects and triggers attack behavior by the
group
 trail pheromone is secreted by social insects
to lead colony members to a food source
Figure 39.11 The chemical control
of fire ant foraging
39.11 Communication Within Social
Groups
• Honeybees have an extremely complex
dance language that directs nestmates to
rich nectar sources
 Karl von Frisch unraveled the details of the
communication system
• a waggle dance is performed by a scout upon its
return to the hive
– the dance traces figure-eight and conveys information
about the direction and distance of the food source
Figure 39.12 The waggle dance of
honeybees
39.11 Communication Within Social
Groups
• Some primates have a “vocabulary” that
allows individuals to communicate the
identity of specific predators
• Language is the primary channel of human
communication
 but nonverbal signals may also convey
information
Figure 39.13 Primate semantics
39.12 Altruism and Group Living
• Altruism is the performance of an action that
benefits another individual at a cost to the actor
 for example, helpers at the nest assist parent birds in
raising young
 at first glance, altruistic behavior appears to be
counter-selective for an individual but the evolution of
this behavior may be explained by
• reciprocity
– mutual exchanges of altruistic behaviors benefit both
participants, provided there are no cheaters
• kin selection
– selection that favors altruism towards relatives
Figure 39.14 An altruistic act—or is it?
Figure 39.15 Kin selection is
common among vertebrates
39.13 Vertebrate Societies
• For the most part, vertebrate social groups
are less rigidly organized and cohesive
than insect societies
 the organization of the group is most
influenced by ecological factors
• Naked mole rats are an exception to the
rule and have a highly organized social
structure with a reproductive division of
labor
Vertebrate Societies
Figure 39.16 Savanna-dwelling
African weaver birds
Figure 39.17 Naked mole rats live
in structured colonies
Figure 39.18 A chimpanzee family
group
39.14 Human Social Behavior
• Sociobiology is the idea that complex
social behaviors of animals, including
humans, should evolve
 human populations exhibit a wide variety of
cultural differences with respect to behavior
 human cultural diversity is no doubt largely
determined by learning and experience
Figure 39.19 A New York City street
scene
Inquiry & Analysis
• What is the most
energetically optimal
mussel size for the
crabs to eat, in mm?
• Do shore crabs tend
to feed on those
mussels that provide
the most energy?
Graph of Energy Budget of a
Shorecrab Mussel Diet