unit 27 behavioral biology
Post on 11-May-2015
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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
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.
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.
27.1 Adaptive Value of Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– During migration, animals move seasonally from one portion of their range to another.
– During hibernation, an animal enters a seasonal dormant state.
27.2 Instinct and Learning
KEY CONCEPT Both genes and environment affect an animal’s behavior.
27.2 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
27.2 Instinct and Learning
– releaser is a simple signal: touch, sight, sound, scent
– herring gulls chicks and red dot releaser
– environmental factors can affect innate behaviors
• Many innate behaviors are triggered by a releaser.
27.2 Instinct and Learning
Many behaviors have both innate and learned components.
• Learning takes many forms.• Habituation occurs
when an animallearns to ignore arepeated stimulus.
• Imprinting is a rapidand irreversiblelearning process.– critical period– Konrad Lorenz
and graylaggeese
27.2 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
27.2 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.
27.2 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
27.2 Instinct and Learning
• There are two types of conditioning.– Operant conditioning: behavior increased or decreased
by positive or negative reinforcement– B.F. Skinner and “Skinner boxes”
27.3 Evolution of Behavior
KEY CONCEPT Every behavior has costs and benefits.
27.3 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
27.3 Evolution of Behavior
• Behavioral costs can be divided into three categories.– energy costs– opportunity costs– risk costs
27.3 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
27.3 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
27.4 Social Behavior
KEY CONCEPT Social behaviors enhance the benefits of living in a group.
27.4 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.
27.4 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
27.4 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.
27.4 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
27.4 Social Behavior
• In altruism, an individual reduces its own fitness to help other members of its social group.– inclusive fitness– kin selection
27.4 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.
27.5 Animal Cognition
KEY CONCEPT Some animals other than humans exhibit behaviors requiring complex cognitive abilities.
27.5 Animal Cognition
Animal intelligence is difficult to define.
• Cognition is the mental process of knowing through perception or reasoning.
• Other factors affecting an animal’s behavior may seem like cognition.
– awareness– ability to judge– ability to solve complex problems
27.5 Animal Cognition
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
27.5 Animal Cognition
• 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
27.5 Animal Cognition
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
27.5 Animal Cognition
• Cultural behavior spreads through a population by learning, not by selection.– taught to one generation by another– aided by living in close proximity
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