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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.