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CHAPTER 32: ANIMAL BEHAVIOR LECTURE OUTLINE 32.1 Nature versus Nurture: Genetic Influences The “nature versus nurture” question asks to what degree our genes (nature) and environmental influences (nurture) affect behavior. Behavior encompasses any action that can be observed and described. Experiments with Lovebirds, Snakes, and Snails Experiments with nest building behavior in Fischer lovebirds suggested this behavior has a genetic basis. Similar results were found with garter snakes and food preference. All of the egg-laying behavior of the marine snail Aplysia is controlled by an egg-laying hormone. Experiments with Humans Human behavior studies have been conducted on twins separated at birth and raised under different environmental conditions. 32.2 Nature versus Nurture: Environmental Influences Environmental influences also affect behavior. Learning is defined as a durable change in behavior brought about by experience. Learning in Birds Laughing gull chicks’ begging behavior appears to be a fixed action pattern behavior, but it is subject to learning. Imprinting Imprinting was first observed in birds when chicks, ducklings, and goslings followed the first moving object they saw after hatching. The behavior develops only during a certain sensitive period. Song Learning White-crowned sparrows sing a species-specific song, but males of a particular region have their own dialect. Social interactions apparently assist learning in birds. Associative Learning A change in behavior that involves an association between two events is termed associative learning. Classical Conditioning In classical conditioning, the presentation of two different types of stimuli at the same time causes an animal to form an association between them. Operant Conditioning During operant conditioning, a stimulus-response connection is strengthened. 32.3 Adaptive Mating Behavior Sexual selection refers to adaptive changes in males and females that lead to an increased ability to secure a mate. Female Choice Two hypotheses regarding female choice are termed the good genes hypothesis and the run-away hypothesis. Male Competition We expect males to compete in order to inseminate as many females as possible. Costbenefit analyses have been done to determine if the benefit of access to mating is worth the cost of competition among males. Dominance hierarchies and territoriality are forms of male competition. Mating in Humans A study of human mating behavior shows that the concepts of female choice and male competition apply to humans as well as animals. Human Males Compete Like many other animals, humans are dimorphic. Males have to compete for the privilege of mating. Females Choose A study suggests that the number one trait females prefer in a male mate is his ability to obtain resources. Men Also Have a Choice Men prefer youthfulness and attractiveness in females, signs that their partner can provide them with children. 32.4 Sociobiology and Animal Behavior Sociobiology applies the principles of evolutionary biology to the study of social behavior in animals. Sociobiologists hypothesize that living in a society has a greater reproductive benefit than reproductive cost. Sociobiology and Human Culture The culture of a human society involves a wide spectrum of customs. It is proposed that human societies originated because of the need for cooperation, communication, and tools in hunting large animals. Altruism versus Self-Interest Altruism can be generally described as a self-sacrificing behavior for the good of another member of the society. In general, altruistic behavior in animals is explained by the concept of kin selection. Helpers at the Nest A helper is contributing to the survival of its own kin when it helps at the nest to raise a relative’s offspring. 32.5 Animal Communication Social behavior in animals requires that they communicate with one another. Communicative Behavior Communication is a signal by a sender that influences the behavior of a receiver. Chemical Communication The term pheromone designates chemical signals in low concentration that are passed between members of the same species. Auditory Communication Auditory communication is faster than chemical communication and it is effective both night and day. Language is the ultimate auditory communication. Visual Communication Visual signals are most often used by species that are active during the day. Tactile Communication Tactile communication occurs when one animal touches another.