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 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 • What external stimulus would cause a dormouse to enter hibernation?
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. 3 Evolution of Behavior • Name an example of optimal foraging? • What behaviors are favored by natural selection? • What is the opportunity cost of a spider's web-spinning behavior? • What is a benefit of territorial behavior? • What are the costs of foraging behavior?
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. 4 Social Behavior • How are male offspring produced in eusocial insect species? • Name a benefit to living in a social group? • How is a pheromone a kind of communication? • Name a social behavior? • Which term describes behavior in which an animal reduces its own fitness to help others?
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