22.1. Behavior Has a
Genetic Basis (p.
367)
A. Behavior Can be Observed and Described
1. Behavior is coordinated response to environmental stimuli.
2. Mechanistic questions are answered by describing how an animal is
biologically equipped to behave.
3. Survival value questions ask how behavior helps exploit resources,
avoid predators, or secure a mate.
B. Inheritance of Migratory Behavior in Birds
1. Migratory birds that are caged and prevented from migrating exhibit migratory restlessness.
2. Peter Berthold noted German blackcap warblers migrate to Africa; those from Cape Verde do not migrate.
a. If migratory behavior was inherited, crossbred birds might show intermediate behavior.
b. Hybrids of German and Cape Verde birds perch-hopped while the Cape Verde birds did not.
3. Andreas Helbig studied the same warbler species for migration patterns.
a. German blackcaps fly southeast to Spain and Africa; Austrian blackcaps fly southwest to Israel and Africa.
b. Hybrids left in a funnel cage left directional marks showing they were intermediate in flight paths.
4. The results of such studies support the hypothesis that behavior has a genetic basis.
C. Feeding Behavior of Garter Snakes
1. Steven Arnold tests the garter snake (Thamnophis elegans) for food preference. (Fig. 22.2)
2. Inland populations are more aquatic and feed on frogs and fish; they refused to feed on slugs.
3. Coastal populations are more terrestrial and feed on slugs.
4. Hybrid newborn garter snakes had an intermediate acceptance of slugs.
5. Work with smell receptors and tongue flicks showed physiological
differences underlie the behavior.
D. Egg-laying Behavior of the Sea Slug Aplysia
1. Behavior shows endocrine involvement.
2. Following copulation, the slug extrudes long strings of eggs and uses head movements to attach eggs to rocks.
3. Scientists isolated an egg-laying hormone (ELH) that causes the animal to lay eggs even if not mated.
4. ELH was identified as a small protein of 36 amino acids that excites reproductive tract causing egg expulsion.
5. Results from recombinant DNA (deoxyribonucleic acid) studies, the ELH gene was isolated and shown to control the egg-laying behavior.
22.2. Behavior Undergoes Development (p. 370)
A. Fixed action patterns (FAPs)
1. Always performed the same way and are elicited by a sign stimulus.
2. Increasingly, investigators find behaviors, formerly thought to be fixed action patterns, develop after practice.
3. Jack Hailman found that the environment is influential in the development of behavioral responses.
a. Gull chicks beg food from parents by pecking at parents' beaks; their accuracy improves with practice.
b. The chicks peck originally at any beak model but soon only peck at models resembling parents. (Fig. 22.3)
c. Interaction between chicks and parents is learning; this interaction was specifically operant condition.
1) Learning is a durable change in behavior brought about by experience.
2) Operant conditioning is a gradual strengthening of stimulus-response connections, resulting from reinforcing a particular behavior; B. F. Skinner was famous for studies in operant conditioning.
4. Imprinting, another form of learning, involves a sensitive period.
a. Chicks, ducklings, and goslings follow first moving object they see after hatching (usually their mother).
b. Douglas Spaulding first observed imprinting; Konrad Lorenz did more extensive work.
c. A sensitive period is the only period during which a particular behavior, including imprinting, develops.
d. Eckhard Hess found that mallard ducks could switch imprinting from humans to female mallards.
B. Birds That Learn to Sing
1. Work by Peter Marler shows young birds learn to sing in part from older birds.
2. Song learning in birds involves a sensitive period when an animal is primed to learn.
3. Neurons critical to song production fire when a song of the same bird dialect is heard.
4. Birds can learn other species' songs; social influence is very strong. (Fig. 22.4)
22.3. Behavior Is Adaptive (p. 372)
A. Behavioral Traits Evolve
1. Behavior has genetic basis.
2. Behavior evolves to adapt individual to reproduce, capture resources, avoid predators.
3. Reproductive behavior of males and females is related to their anatomy and physiology.
a. Males produce sperm in great quantity; compete with other males to inseminate as many females as possible.
b. Females who produce few eggs are selective about their mates; this is called sexual selection.
B. Females Choose
1. Courtship rituals prepare sexes for mating; they allow recognition and help a female choose a mate.
2. Gerald Borgia studied the reproductive behavior in satin bowerbirds (Ptilonorhynchus violaceus).
a. The good genes hypothesis contends females choose mates based on traits that improve male's survival.
b. The run-away hypothesis states females chose mates on basis of traits that attract them to females.
c. More aggressive males kept their bowers in better condition and were chosen as mates by more females.
3. Bruce Beehler
studied raggiana birds of paradise (Paradisaea raggiana) for sexual
selection.
(Fig. 22.5)
a. Males gather in a lek, an assembly area where males display courtship behavior.
b. The male raggiana is polygymous (has more than one mate) and does not help raise the offspring.
c. Since healthy raggiana are parasite free, selection for more feathery males may be related to health.
d. Another experiment showed that barn swallow males reared in nests sprayed with mite-killer had longer tails, and females prefer them.
e. Female choice explains why male birds are so much more showy than females.
C. Males Compete
1. A benefit/cost analysis can be applied to competition between males for mates.
2. Baboons have a dominance hierarchy (Figs. 22.6 and 22.7)
a. Dominance hierarchy is ranking within a group where higher-ranking individuals acquire more resources.
b. Dominance is determined by confrontation where one animal gives way to the other.
c. Male baboons are larger and have large canine teeth; they decide when the troop moves, and they defend it.
d. Females mate with dominant males when ovulation is near.
e. The drawbacks to being large and in danger are outweighed by chance of fathering young.
3. Red deer stake out a territory (Fig. 22.8)
a. Territoriality involves marking or defending a particular area for feeding, mating, and caring for young.
b. T. H. Clutton-Brock studied reproductive success among red deer on the Scottish island of Rhum.
c. Stags compete for females that form a harem that mates only with him.
d. A stag remains at peak fighting ability for a short time; one stag can only father two dozen offspring.
22.4. Animals Are Social (p. 376)
A. Degrees of Sociality
1. There is a wide variety of social behavior among animals.
2. Some animals are largely solitary and join with a member of the opposite sex only to reproduce.
3. Others pair, bond, and cooperate in raising offspring.
4. In a society, members are organized in a cooperative manner, extending beyond sexual and parental behavior.
B. Communication is Varied
1. Communication is an action (signal) by a sender that influences the behavior of a receiver.
2. When the sender and receiver are members of the same species, signals will benefit both sender and receiver.
3. Chemical communication
a. These signals are chemicals (e.g., pheromones, urine, and feces). (Fig. 22.9)
b. A pheromone is a chemical released that causes a predictable reaction of another member of the species.
c. Chemical signals have the advantage of working both night and day.
4. Auditory Communication
a. In auditory communication, the signals are sounds.
b. It has some advantages over other kinds of communication: it is faster than chemical communication, it is effective both night and day, and it can be modified by loudness, pattern, duration, and repetition.
c. Male crickets have calls for reproduction.
d. Birds have various songs for distress, courting and marking territories.
5. Language is the ultimate auditory communication.
a. Only humans have ability to produce many different sounds and put them together in many different ways.
b. Nonhuman primates are limited to about 40 distinct vocalizations with limited meaning.
c. Chimpanzees using artificial language cannot advance beyond the level of a 2-year-old child.
d. It is not proven that chimps are capable of using language to reason or of using grammar.
6. Visual Communication
a. Visual communication is a form of communication that relies on sight as the means of receiving signals.
b. Visual signals are most often used by species that are active during the day.
c. Contests between
males make use of threat postures and possibly prevent outright fighting.
(Fig. 22.6)
d. Defense and courtship displays are exaggerated and always performed same way so that meaning is clear.
7. Tactile Communication
a. Tactile communication occurs when one animal touches another.
b. Gull chicks peck at the parent's beak in order to induce the parent to feed them. (Fig. 22.3)
c. A male leopard nuzzles the female's neck to calm her and to stimulate her willingness to mate.
d. In primates, grooming (one animal cleaning the coat and skin of another) helps cement social bonds.
8. Honeybees combine tactile and auditory signals to communicate direction of a food source. (Fig. 22.11)
a. A bee that has located a good source of pollen returns to the hive and conducts a waggle dance.
b. The dance consists of a figure-8 pattern with body waggles where the loops join.
c. The number of waggles indicates the distance from the hive.
d. The angle of the middle run of the dance indicates the angle to fly relative to the sun.
22.5. Sociobiology and Animal Behavior (p. 378)
A. Sociobiology
1. Sociobiology is application of evolutionary biology principles to the study of social behavior in animals.
B. Social Group Living
1. There are both benefits and costs to living in a social group.
2. Only if benefits, in terms of reproductive success, outweigh the disadvantages will societies evolve.
a. Advantages to living in a social group might include help to avoid predators, raise young, and find food.
1) A herd or flock has more eyes to see approaching predators, etc.
2) The trumpet manucode (a bird) pair bonds for life and both sexes are needed to raise the young.
3) Weaver birds form giant colonies to protect them from predators.
4) Primate members signal the group when they find a bountiful fruit tree.
5) Lions working together can capture a large prey such as a zebra or buffalo.
b. Disadvantages to living in a social group include tension between members, spread of illness and parasites, and reduced reproductive potential.
1) Among red deer, subordinate females are at a disadvantage in producing more prolific sons.
2) Primate grooming may be necessary to keep them healthy since parasites spread easily in groups.
C. Altruism Versus Self-Interest
1. Altruism may decrease reproductive success while benefiting reproductive success of another member of group.
2. Altruism is unexpected because individuals act to increase their own reproductive success.
3. The benefit to altruism involves inclusive fitness---the relative reproductive success of an individual plus that of relatives
a. In social insects, altruism is extreme and is explained on basis that it helps reproducing siblings survive.
1) Only queen among an army ant colony reproduces; three castes of ants have given up reproducing.
2) In social bees and wasps, queen is diploid but drone is haploid; they are 75 percent related to their nestmates but only 50 percent related to their own offspring if they reproduced; thus, it is an advantage to care for the queen and her offspring.
3) In chimpanzees in Africa, males did not interfere with each other's matings because they shared genes.
4. Helpers at the nest
a. Bird offspring from one clutch of eggs may stay at the nest to help parents rear and feed the next batch of offspring.
b. For Florida scrub jays, the number of fledglings produced by an adult pair doubled when they had helpers.
c. Mammal offspring also help their parents; African jackals raise 1.4 pups alone; with helpers they raise 3.6.
d. Green wood-hoopoes (Phoeniculus purpurens) stay at nest to help
5. Helper contributes to survival of its kin.
6. Helper may inherit a parental territory.
7. Helping involves a short-term sacrifice to maximize reproductive potential.