Some Behavior Is Genetically Determined (p. 772)
37.1
37.2
37.3
Approaches to the Study of Behavior (p. 772; Fig. 37.1)
A. Animals respond to their environment in many ways.
B. Behavior encompasses the way an animal responds to stimuli in its environment.
C. Animals with nervous systems have far more complex behaviors.
1. A variety of sense organs enable the perception of environmental stimuli.
D. Explaining Behavior
1. Proximate causation is analyzed by measuring hormone levels or recording the impulse
activity of certain neurons.
2. Ultimate (evolutionary) causation is used to determine how an animal’s behavior
influences survival or reproductive success.
E. A Controversial Field of Biology
1. Whether behavior is a result of nature (instinct) or nurture (learning) has been
controversial.
2. We now know that both instinct and learning play a part in behavior.
Instinctive Behavioral Patterns (p. 773; Fig. 37.2)
A. Ethology is the study of animal behavior in natural conditions.
1. Karl von Frisch, Konrad Lorenz, and Niko Tinbergen won the Nobel Prize in Physiology
or Medicine for their contribution to ethology.
B. An Example of Innate Behavior
1. Konrad Lorenz studied egg retrieval in geese.
a. According to his research, egg retrieval behavior is triggered by a sign stimulus
which is the appearance of an egg outside of the nest.
b. The innate releasing mechanism in the goose’s brain responds to the sign stimulus by
triggering a fixed action pattern.
2. Niko Tinbergen studied sign stimuli in the mating behavior of male stickleback fish.
a. He was able to produce the aggressive display in males by challenging them with
unfish-like models, so long as the sign-stimulus was present.
Gene Effects on Behavior (p. 774; Fig. 37.3)
A. Behavioral genetics is the investigation of behavior by studying genetics.
B. Studies of Genetic Hybrids
1. William Dilger found that a hybrid species of lovebird exhibited the behavior of carrying
nest material that is intermediate between the parents.
C. Studies of Twins
1. A study of 50 sets of human twins revealed many similarities in behavior even though the
twins were raised in different environments.
2. These results show that genes play a key role in behavior.
D. A Detailed Look at How One Gene Affects Behavior
1. In 1996, a new gene in mice was discovered that determines whether or not female mice
nurture their young.
Behavior Can Also Be Influenced By Learning (p. 775)
37.4
How Animals Learn (p. 775; Fig. 37.4)
A. Animals can alter their behavior as a result of learning.
B. Nonassociative learning is the simplest.
1. One form is sensitization in which repeating a stimulus produces a greater response.
2. Another form is habituation in which a decrease in response to a repeated stimulus
occurs.
a. Being able to ignore unimportant stimuli is critical to confronting a barrage of
stimuli.
C. Associative learning involves a change in behavior that involves an association between two
stimuli.
1. The two major types are classical conditioning and operant conditioning.
D. Classical Conditioning
1. The paired presentation of two stimuli causes an animal to form an association.
2. Pavlov caused a dog to salivate when hearing a bell by classical conditioning.
37.5
37.6
E. Operant Conditioning
1. The animal learns to associate its behavior response with reward or punishment.
2. B.F. Skinner conditioned a rat to touch a lever for food reward.
F. Imprinting
1. Imprinting forms preferences to other individuals that will influence behavior later in life.
2. In filial imprinting, social attachments form between parents and offspring.
Instinct and Learning Interact (p. 776; Fig. 37.5)
A. Learning preparedness demonstrates that learning is possible only within the boundaries set
by instinct.
1. Pigeons can learn to associate food with colors but not with sounds.
B. Innate programs [instincts] have evolved because each of them reinforces an adaptive
response.
1. The seed a pigeon eats has a distinct color but makes no sound whereas the approach of a
predator generates noise but involves no distinctive color.
C. Behavior Often Reflects Ecological Factors
1. The genetic component of behaviors has evolved to match an animal to its habitat.
D. The Interaction Between Instinct and Learning
1. Peter Marler’s study in song birds suggests that birds have a genetic template that guides
them to learn the appropriate song.
a. Song acquisition depends on learning, but only the song of the correct species can be
learned.
Animal Cognition (p. 777; Fig. 37.6)
A. Evidence of Conscious Planning
1. Birds in urban areas remove foil caps from milk bottles to get at the cream.
2. Macaques learn to float grain on water to separate it from sand.
3. Chimpanzees strip a twig of its leaves to use as a tool.
4. Sea otters use rocks to break open clams.
B. Problem Solving
1. A chimp figured out how to stack boxes to reach a banana during a 1920s experiment.
2. In Bernard Heinrich’s experiment with a raven, the raven had devised a solution when
presented with a novel problem.
Evolutionary Forces Shape Behavior (p. 778)
37.7
37.8
Behavioral Ecology (p. 778; Fig. 37.7)
A. Investigation of animal behavior is divided into three sorts of questions: the study of its
development, the study of its physiological basis, and the study of its function.
B. Behavioral ecology is the study of how natural selection shapes behavior.
C. All genetic differences need not have survival value.
D. Niko Tinbergen observed that after gull nestlings hatched, the parents quickly removed the
shells.
1. He concluded through experimentation that eggshell removal reduces predation of
unhatched eggs and increases the survival of offspring.
E. Other behaviors enhance energy intake, reduce exposure or increase resistance to disease,
enhance the ability to acquire a mate or in some other way, increase an individual’s fitness.
A Cost-Benefit Analysis of Behavior (p. 779; Figs. 37.8, 37.9)
A. Behavioral ecologists examine the evolutionary advantage of a behavior by asking if it
provides an evolutionary benefit greater than its cost.
B. Foraging Behavior
1. The choice of what food to select and how far to go to seek it is called foraging behavior.
2. It involves a tradeoff between a food’s energy content and the cost of obtaining it.
3. The optimal foraging theory predicts that animals will select food items that maximize
their net energy intake per unit of foraging time.
4. Many animals alter their foraging behavior when predators are present.
C. Territorial Behavior
1. Animals often move over a home range during the day.
Territoriality is the behavior exhibited to defend an individual’s portion of the home
range.
3. Territories are defended by displays that advertise occupation and by overt aggression.
4. An animal is territorial if there is an adaptive value to this behavior.
Migratory Behavior (p. 780; Figs. 37.10, 37.11)
A. Long-range two-way annual movements are called migrations.
1. Migratory is particularly common in birds.
B. The Compass Sense
1. Migrating birds have the ability to detect the earth’s magnetic field and to orient
themselves accordingly.
2. Experiments have indicated that inexperienced starlings migrate using compass sense.
C. The Map Sense
1. Not much is known about map sense.
2. Young birds move with a flock of experienced older birds and learn to recognize cues.
Reproductive Behaviors (p. 782; Fig. 37.12; Table 37.1))
A. Reproductive success is influenced by a number of factors that in turn are directly affected by
an animal’s behavior.
B. Sexual Selection is the competition for mating opportunities.
1. Intrasexual selection leads to evolution of structures used in combat with other males.
a. Combat for mates is a form of agonistic behavior.
2. Intersexual selection or mate choice leads to the evolution of complex courtship
behaviors.
C. The Benefits of Mate Choice
1. Females can benefit by choosing the male that can best care for offspring.
2. In other species, females choose males with the best territories to maximize reproductive
success.
3. Or, females may select vigorous males for their good genetic makeup.
D. Mating Systems
1. The typical number of mates an animal has during its breeding season is called the
mating system.
2. There are three principal mating systems: monogamy, polygyny, and polyandry.
3. Mating systems have evolved to maximize reproductive fitness.
E. Reproductive Strategies
1. A set of behaviors can evolve to maximize the reproductive success of a particular
species.
2.
37.9
37.10
Social Behavior (p. 784)
37.11
Communication Within Social Groups (p. 784; Figs. 37.13, 37.14, 37.15)
A. Many animals live in social groups in which information is communicated between group
members.
1. In some mammalian societies, “guards” give an alarm call when a predator appears.
2. Social insects secrete alarm pheromones that trigger attack behavior.
3. Ants deposit trail pheromones between the nest and a food source.
4. Honeybees have an extremely complex dance language which directs nest mates to
nectar.
B. The Dance Language of the Honeybee
1. A scout bee performs a behavior pattern (waggle dance) on a vertical comb.
2. The path during the dance resembles a figure eight.
3.
37.12
37.13
On the straight part of the path, the bee vibrates or waggles her abdomen.
a. The scout bee indicates the direction of food by representing the angle between the
food, hive, and sun.
b. The distance is indicated by the tempo of the dance.
C. Primate Language
1. Vocalizations of African vervet monkeys distinguish eagles, leopards, and snakes.
2. Chimps and gorillas learn to recognize a large number of symbols and use them to
communicate abstract concepts.
3. All human languages share basic structural similarities.
Altruism and Group Living (p. 786; Figs.37.16, 37.17)
A. Altruism is the performance of an action that benefits another individual at a cost to the actor.
B. One would expect alleles for altruism to be a disadvantage.
1. Some have proposed that a particular trait evolved for the good of the species.
a. But, natural selection operates on individuals, not on the species.
2. Group selection can occur but is rare.
C. It may be that seemingly altruistic acts are also helpful to the individual.
D. Reciprocity
1. Reciprocal altruism occurs when “partnerships” form in which mutual exchanges of
altruistic acts occur because it benefits both.
a. Cheaters (non-reciprocators) are discriminated against and are cut off from receiving
future aid.
E. Kin Selection
1. Natural selection will favor any strategy that increases the net flow of an individual’s
alleles to the next generation.
2. Selection that favors altruism directed toward relatives is called kin selection.
F. Examples of Kin Selection
1. Ground squirrels give alarm calls when they spot a predator.
a. Researchers found that females who have relatives nearby are more likely to give
alarm calls than females with no kin nearby.
2. The white-fronted bee-eater lives in colonies of 100–200 birds.
a. Kin selection is important in determining helping behavior.
b. Helpers are usually males which are related to other birds in the colony.
c. When birds have the choice of helping different parents, they usually choose the
parents to which they are most closely related.
Animal Societies (p. 788; Fig. 37.18)
A. A society is a group of organisms of the same species that are organized in a cooperative
manner.
B. Insect societies have evolved mainly in two groups of insects: Hymenoptera (ants, bees, and
wasps) and Isoptera (termites).
C. Insect societies contain different worker classes, or castes.
D. In honeybees, a queen bee suppresses the reproduction of other females, and male bees are
produced only for the purpose of mating.
E. Vertebrate social groups are usually less rigidly organized and cohesive compared to insect
societies.
F. Vertebrate societies, like insect societies, have particular types of organization.
G. African weaver birds exemplify the relationship between ecology and social organization.
1. One set of species lives in the forest and builds camouflaged, solitary nests.
a. Males and females are monogamous.
b. They forage for insects to feed their young.
2. Another group nests in colonies in trees on the savanna.
a. They are polygynous and feed in flocks on seeds.
3. The feeding and nesting habits of these two sets of species are correlated with their
mating systems.
37.14
Human Social Behavior (p. 789; Fig. 37.19)
A. One of the most profound lessons of biology is that we humans are animals, close relatives of
the chimpanzee.
B. Genes and Human Behavior
1. Ethology has provided much evidence that behaviors do indeed evolve.
2. Sociobiology is the study of social behavior and was pioneered by E.O. Wilson of
Harvard University.
a. Human facial expressions, similar the world over, have deep genetic basis as infants
born blind still smile and frown.
b. Learning also has a huge impact on how humans behave.
4. Diversity is the Hallmark of Human Culture
a. The variation in social behavior of other species is small compared to the enormous
diversity of human cultures.
b. Both heredity and learning play key roles in determining how we behave.