Transcript Ch 32 Notes

Chapter 32
Behavioral
Ecology
Lecture Outline
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32.1 Nature versus Nurture:
Genetic Influences
• Behavior
– Any action that can be observed and
described
– Genes, to a degree, control behavior
32.1 Nature versus Nurture:
Genetic Influences
• Experiments with Lovebirds, Snakes, and Snails
– Lovebird Nesting Behavior
• Fischer lovebirds, Agapornis fischeri, cut strips
from leaves and carry them to their nest site
• Peach-face lovebirds, Agapornis roseicollis, also
cut strips but tuck them into their rump feather and
carry them that way
• Hybrid lovebirds exhibit intermediate behavior.
They cut strips and try to tuck them into feathers,
but are unsuccessful
• These studies support the hypothesis that behavior
has a genetic basis
Nest Building Behavior in Lovebirds
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a. Fischer lovebird with nesting material in its beak
b. Peach-faced lovebird with nesting material in its rump feathers.
© Joe McDonald, Courtesy Jeff and Wendy Martin, Refuge for Saving the Wildlife, Inc.
32.1 Nature versus Nurture:
Genetic Influences
• Experiments with Lovebirds, Snakes, and Snails
– Garter Snake Experiments
• Genetic role in food preference
– Inland populations of garter snakes are aquatic and feed
in the water on fish and frogs
– Coastal populations are terrestrial and feed on slugs
– In the laboratory, inland snakes refused slugs, while
coastal snakes readily accepted them
• Hybrid snakes exhibited intermediate acceptance of
slugs as food
• This study suggests a genetic basis for feeding
preference
32.1 Nature versus Nurture:
Genetic Influences
• Experiments with Lovebirds, Snakes, and Snails
– Garter Snake Experiments
• Determined that sensory receptors are specific for prey
– Researchers presented baby snakes with slug extract on
cotton swabs and then counted the number of tongue
flicks
• Coastal snakes had a higher number of tongue flicks
than inland snakes
• Apparently, coastal snakes have many receptors on
their tongues for taste and smell of slugs, inland
snakes do not
• A genetic difference between the two populations results in a
physiological difference in nervous systems.
Feeding Behavior in Garter Snakes
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inland
coastal
Inland garter snake does not eat slugs.
Percentage of Snakes
20
15
10
5
0
0.5
Coastal garter snake eats slugs.
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Tongue Flicks per Minute
(coastal): © John Sullivan/Monica Rua/Ribbitt Photography; (inland): © R. Andrew Odum/Peter Arnold
4.5
5.0
5.5
6.0
32.1 Nature versus Nurture:
Genetic Influences
• Experiments with Lovebirds, Snakes, and
Snails
– Snail experiments
• Show role of endocrine system in behavior
• ELH - egg-laying hormone was isolated in Aplysia
snails
• ELH controls all aspects of egg laying behavior
– After mating, snail pulls egg string with mouth, winds it in
a loose ball, and attaches it to an object
– When given ELH, snail exhibits all behaviors even
without mating
32.1 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
• Lend support to the hypothesis that at least certain
types of behavior are primarily influenced by
nature (i.e., genes)
32.2 Nature versus Nurture:
Environmental Influences
• Environmental influences (nutire) also
affect behavior
• Fixed Action Patterns (FAP): specific
behaviors elicited by a sign stimulus
• Learning: A durable change in behavior
brought about by experience
32.2 Nature versus Nurture:
Environmental Influences
• Learning in Birds
– Appears to be a FAP but involves learning
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Pecking
accuracy of
two-day old
Pecking
accuracy
of newborn
b.
Mean accuracy of pecking model for all chicks tested
Hits (percent)
100
a. Laughing gull adult and chick, Leucophaeus atricilla
75
50
25
0
0
c.
1
2
Days in Nest
3
4
32.2 Nature versus Nurture:
Environmental Influences
• Learning in Birds
– Imprinting: a simple form of learning
• Young birds follow the first moving object they see
– Sensitive period: time during which imprinting
may occur
• Social interactions between parent and offspring
during the sensitive period are important
– Young birds are sensitive to parents
vocalization even before hatching
32.2 Nature versus Nurture:
Environmental Influences
• Learning in Birds
– Song Learning
• White-crowned sparrows: species-specific song with
different dialects; experiments show learning plays a role
• Birds that heard no songs: sang an undeveloped song as
adults
• Birds that heard species song: 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
32.2 Nature versus Nurture:
Environmental Influences
• Associative Learning
– A change in behavior that involves an association
between two events
– Classical Conditioning
• The presentation of two different types of stimuli at
the same time causes an animal to form an
association between them
– Operant Conditioning
• A stimulus-response connection is strengthened
• Training an animal by rewarding it
Classical Conditioning
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saliva at
sight of food
(unconditioned
response)
saliva at
sound of bell only
(conditioned response)
sound of bell
(conditioned
stimulus)
food
(unconditioned
stimulus)
apparatus to
measure saliva
32.3 Animal Communication
• Communication
– An action by a sender that influences the
behavior of the receiver
– Chemical Communication: Pheromones
• Powerful chemical signals passed in low
concentration
• May be released into the air or used in territory
marking
– Auditory Communication
• Very rapid and can be modified for specific
situations
Use of a Pheromone
(Chemical Communication)
8
7
6
5
4
3
2
1
Frequency (kilocycles
per second)
Frequency (kilocycles
per second)
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0
0
0.5 Seconds
Eagle
a.
8
7
6
5
4
3
2
1
b.
(main): © Arco Images/GmbH/Alamy; (inset): © Fritz Polking/Visuals Unlimited
0.5 Seconds
Leopard
32.3 Animal Communication
• Communication
– Visual Communication
• Most used by diurnal species - must be able to be
seen
• Plumage, courtship “dances”, aggressive displays,
firefly flashes
– Tactile Communication
• Occurs when one individual touches another
• Laughing gull chicks peck at the parent’s beak to
induce the parent to feed them
• Waggle dance of honeybees
A Male Baboon Displaying Full Threat
Communication Among Bees
(Tactile Communication)
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xº
xº
a.
b.
a: © OSF/Animals Animals
32.4 Behaviors that Affect Fitness
• Assume that most behavior is subject to
natural selection
• Much of the behavior we observe must
have adaptive value
• Territoriality
– Defending a portion of the home range
– More likely during reproductive time period
– Cost – takes energy to sing and fight
– Benefits outweigh the cost
32.4 Behaviors that Affect Fitness
• Foraging For Food
– Animals need to ingest food that will provide
more energy than the effort expended
acquiring the food
– Optimal foraging theory
– Animals face trade-off of foraging for food or
avoiding predators
Energy Gain (J/s)
6.0
6
5
4.0
4
3
2.0
2
1
0
0
10
20
30
40
Length of Mussel (mm)
50
Number of Mussels Eaten per Day
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32.4 Behaviors that Affect Fitness
• Reproductive Strategies and Fitness
– Usually, primates are polygamous
• Males monopolize multiple females
• Females invest more in offspring
– Adaptive for females to be concerned with good food
source – clump around food source
• Males are expected to compete with other males
for the limited number of receptive females
available
32.4 Behaviors that Affect Fitness
• Sexual Selection
– Form of natural selection that favors features
that increase an animal’s chances of mating
– Features are adaptive in the sense that they
lead to increased fitness
– Often results in:
• Female choice – limited number of eggs to fertilize
• Male competition – fertilize as many eggs as
possible
32.4 Behaviors that Affect Fitness
• Mating in Humans
– Human Males Compete
• Women invest more time and energy in a child biologically
– Nine month pregnancy and then lactation
• Men only need to contribute sperm during sex act
• Result: men are more available for reproduction than women
– Because more men are available, they must compete
• Humans are dimorphic: men are larger and stronger perhaps
as a result of past selection by females
– Males pay a price. The average life span is seven years
less than females
32.4 Behaviors that Affect Fitness
• Mating in Humans
– Females Choose
• In one study, the ability to achieve financial success was
found to be the most preferred trait by females
• Other studies have shown that facial body symmetry is
important
– Men Also Have a Choice
• Men prefer youthfulness and attractiveness in females, signs
that their partner can provide them with children.
• By choosing younger women, older men can increase their
fitness.
32.4 Behaviors that Affect Fitness
• Societies and Fitness
– Sociobiologists hypothesize that societies
form when living in a society has a greater
reproductive benefit than reproductive cost
– Group living does have its benefits
• Avoid predators, rear offspring, find food
– Group living also has its disadvantages
• Disputes, illness
32.4 Behaviors that Affect Fitness
• Sociobiology and Human Culture
– Humans live in organized societies
– The culture of a human society involves a wide
spectrum of customs
– The earliest organized societies may have been the
“hunters-gatherers”
– A predatory lifestyle likely encouraged the evolution of
intelligence and the development of language
32.4 Behaviors that Affect Fitness
• Altruisms versus Self-Interest
– Self-sacrificing behavior for the good of another
member of the society
– Kin selection
• Close relatives share many of your genes, it may
make sense to self-sacrifice to save them
– Inclusive fitness
• An individual’s personal reproductive success, as
well as that of his or her relatives, and thus to an
individual’s total genetic contribution to the next
generation
32.4 Behaviors that Affect Fitness
• Reciprocal Altruism
– Minimal short-term reproductive sacrifice
made to maximize future reproductive
potential
– Benefits
• Helper contributes to survival of kin
• Helper more likely to inherit territory
Inclusive Fitness
A meerkat acts as
a babysitter
for its siblings.