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Behavioral Ecology
Chapter 37
Nature vs. Nurture
 Behavior
 To what degree do our
genes (nature) and
influences (nurture)
affect behavior?
Nature versus Nurture:
Genetic Influences
 Lovebird Nesting Behavior
 Genetic role in nest
Fischer lovebirds,
Agapornis fischeri
lovebirds, Agapornis
Hybrid lovebirds
exhibit intermediate
Nature versus Nurture:
Genetic Influences
 Garter Snake Experiments
Genetic role in food
In the wild:
 Inland populations of
garter snakes are
 Coastal populations are
In the laboratory:
 Inland snakes refused
 Coastal snakes readily
accepted them
 Hybrid snakes exhibited
acceptance of slugs as
Nature versus Nurture:
Genetic Influences
 Garter Snake Experiments
Sensory receptors are
specific for prey
 Presented baby snakes
with slug extract on
cotton swabs
 Coastal
 Inland
Genetic difference –
physiological difference
Nature versus Nurture:
Genetic Influences
 Experiments with Humans
Twin Studies
Look at characteristics
of twins raised apart
Many share common
preferences in food,
activity patterns, and
mate selection
Nature versus Nurture:
Environmental Influences
 Fixed Action Patterns (FAP)
Specific behaviors
elicited by a sign stimulus
 Learning
 A durable change in
behavior brought about
by experience
Nature versus Nurture:
Environmental Influences
 Learning in Birds
Imprinting: a simple
form of learning
 Sensitive period
 Social interactions
between parent and
offspring during the
sensitive period are
Nature versus Nurture:
Environmental Influences
 Learning in Birds
Song Learning
 White-crowned sparrows
 Species-specific song with different dialects
Three groups:
 Birds that heard no songs
 Sang an undeveloped song as adults
 Birds that heard White-crowned sparrows
 Sang in that dialect as long as tape was played
during a sensitive period
 Birds that had adult tutor
 Sang the tutor’s song even if a different species
and no matter when tutoring began
Nature versus Nurture:
Environmental Influences
 Associative learning
1. Classical Conditioning
The presentation of two
different types of stimuli at the
same time
Causes an animal to form an
association between them
2. Operant Conditioning
 A stimulus-response
connection is strengthened
 Training an animal by
rewarding it
Other means of learning….
 Animals may learn through
insight, imitation, and
 Insight learning
 An animal suddenly
solves a problem
without any prior
experience with the
 Habituation
 An animal no longer
responds to a repeated
Mating Behaviors
 Sexual Selection
Adaptive changes that increase ability to
attract a mate
Influences fitness
 Three influences on mating:
Female Choice
Male Competition
Human Mating
1. Female Choice
 Two Hypotheses:
Good Genes Hypothesis
Females choose mates on
basis of traits that improve
Run-away Hypothesis
Females choose mates on
basis of traits that improve
2. Male Competition
 Males can produce many offspring because
continuously produce sperm in large numbers
Less time and energy invested in reproduction
Males compete to inseminate as many
females as possible
 Cost-benefit analyses
Is the benefit of access to mating worth the
cost of competition among males??
2. Male Competition
 Males and females have
separate dominance
 Higher-ranking animal
has greater access to
resources than a
lower-ranking animal
 Dominance is decided
by confrontations
3. Mating in Humans
 Human Males Compete
 Humans are dimorphic
 Men are larger and stronger likely as result of
past selection by females
 Males pay a price - the average life span is
seven years less than females!
 Applies the principles of evolutionary biology to the
study of social behavior in animals
 Hypothesis
Living in a society has a greater reproductive benefit
than reproductive cost
 Benefits of Group Living
 Helps an animal avoid predators, rear offspring, and
find food
 Disadvantages to Group Living
 Competition among members of the group for
 Exposes group members to illnesses and parasites
 Helpers at the Nest
Minimal short-term
reproductive sacrifice made
to maximize future
reproductive potential
Helper contributes to survival
of kin
Sociobiology and Human Culture
 Humans live in organized societies
 Culture of a human society involves a wide
spectrum of customs
 Earliest organized societies may have been
the “hunters-gatherers”
Predatory lifestyle likely encouraged the
evolution of intelligence and the development
of language
Animal Communication
 Communication
 4 types communication signals:
 Chemical
 Auditory
 Visual
 Tactile
Animal Communication
 Chemical
Powerful chemical signals
passed in low
May be released into the
air or used in territory
Animal Communication
 Auditory
Very rapid and can be
modified for specific
Animal Communication
 Visual
Most used by diurnal
species-must be able
to be seen
Plumage, courtship
“dances”, aggressive
displays, etc
Animal Communication
 Tactile
Occurs when one
individual touches