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 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
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. 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
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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