27 1 Adaptive Value of Behavior KEY CONCEPT
27. 1 Adaptive Value of Behavior KEY CONCEPT Behavior lets organisms respond rapidly and adaptively to their environment.
27. 1 Adaptive Value of 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 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 KEY CONCEPT 27. 2 Both genes and environment affect an animal’s behavior.
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, 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 and potato-washing behavior
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 KEY CONCEPT 27. 3 Every behavior has costs and benefits.
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
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
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
27. 1 Adaptive Value of Behavior KEY CONCEPT 27. 4 Social behaviors enhance the benefits of living in a group.
27. 1 Adaptive Value of 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. 1 Adaptive Value of 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. 1 Adaptive Value of 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. 1 Adaptive Value of 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. 1 Adaptive Value of Behavior • In altruism, an individual reduces its own fitness to help other members of its social group. – inclusive fitness – kin selection
27. 1 Adaptive Value of 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. 1 Adaptive Value of Behavior KEY CONCEPT 27. 5 Some animals other than humans exhibit behaviors requiring complex cognitive abilities.
27. 1 Adaptive Value of Behavior 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.
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
27. 1 Adaptive Value of Behavior • 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. 1 Adaptive Value of Behavior 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. 1 Adaptive Value of Behavior • 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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