Transcript 27.1 Adaptive Value of Behavior

27.1 Adaptive Value of Behavior
KEY CONCEPT
Behavior lets organisms respond rapidly and
adaptively to their environment.
27.1 Adaptive Value of Behavior
Behavioral responses to stimuli may be adaptive.
• Detecting and responding to stimuli is key to an individual’s
survival.
• Internal stimuli tell an animal what is occurring in its own
body.
– hunger
– thirst
– pain
27.1 Adaptive Value of Behavior
• External stimuli give an animal information about its
surroundings.
– sound
– sight
– changes in day length or temperature
Fig. When
threatened, a
pufferfish responds
by inflating itself with
water until its spines
stick out from its
rounded body.
27.1 Adaptive Value of Behavior
• Specialized cells that are sensitive to stimuli detect sensory
information.
– information is transferred to the nervous system
– nervous system may activate other systems in response
• Animal behaviors help to maintain homeostasis.
27.1 Adaptive Value of Behavior
• Kinesis and taxis are two types of movement-related
behaviors.
– Kinesis is an increase in random movement.
– Taxis is movement in a particular direction.
27.1 Adaptive Value of Behavior
Internal and external stimuli usually interact to trigger
specific behaviors.
• Most behaviors are a response to both internal and external
stimuli.
• External stimuli may trigger internal stimuli.
• Green anole reproductive behavior is triggered by internal
and external stimuli.
Fig. The extended red
dewlap of this male green
anole announces to females
that it is ready to mate. The
dewlap is also used in
territorial defense as a "keep
out" signal to other males.
27.1 Adaptive Value of Behavior
Some behaviors occur in cycles.
• A circadian rhythm is the daily cycle of activity.
– occurs over 24-hour period
– run by a biological clock
27.1 Adaptive Value of Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– During hibernation, an animal enters a seasonal
dormant state.
Fig. During
hibernation, the
dormouse's blood
temperature
drops from 36°C
(97°F) to just
above 0°C
(32°F).
27.1 Adaptive Value of Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– During hibernation, an animal enters a seasonal dormant
state.
– During migration, animals move seasonally from one
portion of their range to another.
27.1 Adaptive Value of Behavior
Innate behaviors are triggered by specific internal and
external stimuli.
• An instinct is a complex
inborn behavior.
• Instinctive behaviors
share
several characteristics.
– innate, born with the
ability or performed
correctly the first time
– relatively inflexible
27.1 Adaptive Value of Behavior
• Many innate behaviors are triggered by a releaser.
– releaser is a simple signal:
touch, sight, sound, scent
– herring gulls chicks and red
dot releaser
– environmental factors can
affect innate behaviors
27.1 Adaptive Value of Behavior
Many behaviors have both innate and learned
components.
• Learning takes many forms.
• Habituation occurs
when an animal
learns to ignore a
repeated stimulus.
• Imprinting is a rapid
and irreversible
learning process.
– critical period
– Konrad Lorenz
and graylag
geese
27.1 Adaptive Value of Behavior
• In imitation, animals learn by observing the behaviors of
others.
– young male songbirds
learn songs by listening
to adult males
– Snow monkeys learn to
wash their potatoes
before eating them by
imitating the behavior of
other individuals.
27.1 Adaptive Value of Behavior
Learning is adaptive.
• Animals that can learn can better adapt to new situations.
• In associative learning, a specific action is associated with
its consequences.
• Conditioning is one type of associative learning.
27.1 Adaptive Value of Behavior
• There are two types of conditioning.
– Classical conditioning: previously neutral stimulus
associated with behavior triggered by different stimulus
– Ivan Pavlov and salivating dog
27.1 Adaptive Value of Behavior
• There are two types of conditioning.
– Operant conditioning: behavior increased or
decreased by positive or negative reinforcement
– B.F. Skinner and “Skinner boxes”
27.1 Adaptive Value of Behavior
Even beneficial behaviors have associated costs.
• The benefits of a behavior are increased survivorship and
reproduction rates.
– both increase an individual’s fitness
– both have costs
27.1 Adaptive Value of Behavior
• Behavioral costs can be divided into three categories.
– energy costs
– opportunity costs
– risk costs
Fig. While mating with
the female, the smaller
male Australian redback
spider somersaults
directly over the female's
mouth, offering himself
as her next meal.
27.1 Adaptive Value of Behavior
Animals perform behaviors whose benefits outweigh their
costs.
• Behaviors evolve only if they improve fitness.
• Territoriality refers to the control of a specific area.
– benefits: control resources
– costs: energy and time
Fig. These male Siberian tigers
are very territorial. Fights over
territory can lead to serious
injury or even death.
27.1 Adaptive Value of Behavior
• Optimal foraging states that natural selection favors
behaviors that get animals the most calories for the cost.
– benefits: amount of energy gained
– costs: energy used to search for, catch, and eat food;
risk of capture; time
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Animal intelligence is difficult to define.
• Cognition is the mental process of knowing through
perception or reasoning.
– awareness
– ability to judge
– ability to solve complex
problems
• Other factors affecting an
animal’s behavior may seem
like cognition.
Fig. While considered to have fewer cognitive
abilities than other primates, studies have
shown that lemurs have the ability to
remember long sequences of images and can
place images in the correct order.
27.1 Adaptive Value of Behavior
Some animals can solve problems.
• Insight is the ability to solve a problem mentally without
repeated trial and error.
– observed in primates, dolphins, and corvids
– chimpanzee retrieving hanging bananas
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• Tool use helps an animal accomplish a task.
– some dolphins use sponges to protect and hunt
– crows and chimpanzees make probing sticks
– capuchin monkeys use rocks to crack nuts
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Cognitive ability may provide an adaptive advantage for
living in social groups.
• Intelligence in animals seems to be correlated with two
characteristics.
– relatively large brains for their body size
– live in complex social groups
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• Cultural behavior spreads through a population by learning,
not by selection.
– taught to one generation by another
– aided by living in close proximity