Transcript Adaptive Value of Behavior

Adaptive Value of Behavior
KEY CONCEPT
Behavior lets organisms respond rapidly and
adaptively to their environment.
Adaptive Value of Behavior
Behavioral responses to stimuli may be adaptive.
• Behavior – any action that an individual carries out in
response to a stimulus or to the environment
• Internal stimuli tell an animal what is occurring in its own
body.
– hunger
– thirst
– pain
Adaptive Value of Behavior
• External stimuli give an animal information about its
surroundings.
– sound
– sight
– changes in day length or temperature
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.
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.
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.
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
Adaptive Value of Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– Hibernation - an animal enters a seasonal dormant
state.
• Estivation – Animal dormancy during times of heat & dryness
– Migration - animals move seasonally from one portion
of their range to another.
Instinct and Learning
KEY CONCEPT
Both genes and environment affect an animal’s
behavior.
Instinct and Learning
Innate behaviors are triggered by specific internal and
external stimuli.
• An instinct is a complex inborn behavior.
• Instinctive behaviors share
several characteristics.
– innate, or performed
correctly the first time
– relatively inflexible
Instinct and Learning
• 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
Instinct and Learning
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
Instinct and Learning
• In imitation, animals learn by observing the behaviors of
others.
– young male songbirds
learn songs by listening
to adult males
– snow monkeys and
potato-washing
behavior
Instinct and Learning
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.
Instinct and Learning
• There are two types of conditioning.
– Classical conditioning: previously neutral stimulus
associated with behavior triggered by different stimulus
– Ivan Pavlov and salivating dog
– Operant
conditioning:
behavior increased or
decreased by
positive or negative
reinforcement
– B.F. Skinner and
“Skinner boxes”
Evolution of Behavior
KEY CONCEPT
Every behavior has costs and benefits.
Evolution 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
Evolution of Behavior
• Behavioral costs can be divided into three categories.
– energy costs
– opportunity costs
– risk costs
Evolution 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
Evolution 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
Social Behavior
KEY CONCEPT
Social behaviors enhance the benefits of living in a
group.
Social Behavior
Living in groups also has benefits and costs.
• Social behaviors evolve when the benefits of group living
outweigh its costs.
– benefits: improved
foraging, reproductive
assistance, reduced
chance of predation
– costs: increased
visibility, competition,
disease contraction
• Group living requires learning social structure and
membership.
Social Behavior
Social behaviors are interactions between members of the
same or different species.
• Animals use communication to keep in contact.
– visual
– sound
– touch
– chemical
Social Behavior
• Courtship displays are used to evaluate the fitness of a
potential mate.
• Defensive behaviors are used to protect the individual
and/or the group.
Social Behavior
Some behaviors benefit other group members at a cost to
the individual performing them.
• There are many types of helpful social behavior.
– cooperation
– reciprocity
– altruism
Social Behavior
• In altruism, an individual reduces its own fitness to help
other members of its social group.
– inclusive fitness
– kin selection
Social Behavior
Eusocial behavior is an example of extreme altruism.
• Eusocial species live in large groups of mostly
nonreproductive individuals.
– haplodiploid species: social insects (wasps, bees, ants)
Queen
Minor worker
Major worker
– diploid species: termites, snapping shrimp, naked mole
rats
• Eusocial behaviors likely evolve by kin selection.