33.1 Approaches to the Study of Behavior

2. 33.1 Approaches to theStudy of Behavior • Behavior can be defined as the way an organism responds to stimuli in its environment • The most complex behaviors are exhibited by animals with nervous systems • Proximate causation – How does it work? • Focus of the field of psychology • Ultimate causation – Why did it evolve? • Focus of the field of ethology (evolutionary behavior)

3. 33.1 Approaches to theStudy of Behavior • The study of behavior has had a long history of controversy • Is behavior the result of nature (instinct) or nurture (learning)? • This is no longer considered an “either-or” proposition • We now know that instinct and learning play significant roles

4. 33.2 Instinctive Behavioral Patterns • Early research in animal behavior focused on patterns that appeared to be instinctive or innate • These are the same in all individuals of a species • Appear to be based on preset paths in the nervous system • Ethology is the study of animal behavior in natural conditions • Its founders were Karl von Frisch, Konrad Lorenz, and Niko Tinbergen

5. Fig. 33.2a Examples of Innate Behavior • Egg retrieval by geese • Behavior is triggered by a sign stimulus • Egg out of nest • Innate releasing mechanism provides the neural instructions that detect stimulus • A fixed action pattern is triggered • Intricate egg retrieval behavior

6. Fig. 33.2b • Male stickleback fish develop red coloration on their undersides during breeding season • React aggressively to approach of other males • Sign stimuli are often not very specific • Redcolor is the sign stimulus • Fish displayed aggressive postures when challenged with unfishlike models with red strips!

7. 33.3 Gene Effects on Behavior • Behavioral genetics is the study of how genes influence behavior • Many behaviors are inherited in Mendelian fashion • Crosses of two species showing different behaviors yields hybrids with “intermediate” behavior • A study of human twins revealed the following • Identical twins separated at birth and raised apart developed many similarities in personality • Fraternal twins raised together had personalities no more similar than those raised apart

8. Normal mother Fig. 33.3 Mother with two mutant fosB alleles 33.3 Gene Effects on Behavior • In 1996, the fosB gene was discovered in mice • It seems to determine whether female mice will nurture their young

9. 33.4 How Animals Learn • Learning is the modification of animal behavior as a result of previous experiences • Non-associative learning • No requirement for an association between two stimuli or between a stimulus and a response • Sensitization • Repeating a stimulus produces greater response • Habituation • Decrease in response to a repeated stimulus • Learning not to respond to a particular stimulus

10. Associative learning • Involves formation of an association between two stimuli or between a stimulus and a response • The behavior isconditioned • Classical conditioning • Paired presentation of two stimuli causes an animal to create an association between them • Pavlovian conditioning • Operant conditioning • An animal learns to associate its behavioral response with a reward or punishment • Trial-and-error learning

11. Fig. 33.4 Imprinting • Social attachments to other individuals that will profoundly influence behavior later in life • Filial imprinting occurs between parents and offspring • Birds will follow the first object they see after hatching • They direct their social behavior toward that object as their mother Konrad Lorenz

12. 33.5 Instinct and Learning Interactto Determine Behavior • Some animals have innate predisposition toward forming certain associations • Pigeons learn to associate food with colors but not sounds • However, they associate danger with sounds not colors • This learning preparedness demonstrates that learning is possible only within the boundaries set by instinct (genes) • Knowledge of an animal’s ecology is key to understanding what an animal is capable of learning • Clark’s nutcracker have an extraordinary spatial memory • These birds have a large hippocampus

13. Fig. 33.5 • White-crowned sparrows that heard no song at all during rearing, had a poorly developed song as adults • Courtship songs sung by mature birds are species-specific • The same was true if they heard only the song of a different species, the song sparrow • However, birds that heard the song of their own species, sang a fully-developed “white-crowned” song as adults Thus, song development involves both instinct and learning

14. 33.6 Animal Cognition • A central question in animal behavior is whether non-human animals show cognitive behavior • Do they process information and respond in a manner that suggests thinking? • Some examples provide evidence of conscious planning • Japanese macaques can separate grain from sand • Chimpanzees use twigs to probe entrance to termite nest • Sea otters bash clams against rocks to break them open

15. Fig. 33.6 • There is also compelling evidence that animals can solve problems • Chimpanzees could not get to bananas by jumping • They ultimately got to it by placing boxes on top of each other and climbing on them! • Ravens figured out how to get to meat at the end of a string • They pulled up a bit of string and stepped on it • This process was repeated until the food was within reach!

16. 33.7 Behavioral Ecology • The study of animal behavior can be divided into • 1) A study of its development • 2) A study of its physiological basis • 3) A study of its function • Behavioral ecology is the study of how natural selection affects behavior • Focuses on the adaptive significance of behavior • How behavior may increase survival and reproductive success, or fitness

17. 33.7 Behavioral Ecology • Adaptive traits confer evolutionary advantages in different ways • Some behaviors reduce predation • Egg-shell removal by gulls reduce predation by crows • Other behaviors enhance energy intake • This allows more offspring to be supported • Other behaviors increase resistance to disease • Still others enhance the ability to acquire a mate

18. 33.8 A Cost-Benefit Analysisof Behavior • Every behavior that offers a survival advantage for an individual comes with an associated cost • Foraging behavior allows an animal to choose what food to select, and how far to go seeking it • Optimal foraging theory • Animals select foods that maximize their net energy intake per unit of foraging time • However, avoiding predators is an important consideration

19. Fig. 33.8 Territoriality is behavior in which individual members of a species maintain exclusive use of an area • Territories are defended by displays and overt aggression • Sunbirds increase nectar availability by defending flowers • However, a defensive cost is increased predation • Thus, for a behavior to be favored by natural selection, the benefits have to outweigh the costs

20. 33.9 Migratory Behavior • Many animals breed in one part of the world, and spend the rest of the year in another • Long-range two-way annual movements like this are called migrations • Migratory behavior is particularly common among birds • Ducks and geese • Warblers • Starlings

21. 33.9 Migratory Behavior • Compass sense – An innate ability to move in a particular direction (called follow a bearing) • Map sense – A learned ability to adjust a bearing depending on the animal’s location • Experiments on starlings indicate that inexperienced birds migrate with an innate compass sense • On the other hand, older experienced birds use a learned map sense to aid their navigation

22. Fig. 33.9 Starlings learn how to navigate Transport of captured birds Flight of experienced birds Flight of inexperienced birds

23. 33.9 Migratory Behavior • How is the compass sense achieved? • Migrating birds detect the earth’s magnetic field and orient themselves with respect to it • Sun and stars may also be used for orientation • How is the map sense achieved? • Recognition of certain cues, like the position of mountains and coastlines • Migration through featureless terrain presents more of a puzzle

24. 33.10 Reproductive Behaviors • Reproductive behaviors encompass a variety of animal behaviors, including courtship • Competition for mating opportunities has been termed sexual selection • Intrasexual selection • Competition between members of one sex (usually males) • Intersexual selection • Essentially, mate choice

25. Fig. 33.10 • Intrasexual selection leads to evolution of structures used in combat with other males • Deer’s antlers or ram’s horns • Intersexual selection leads to evolution of complex courtship behaviors and “ornamental” structures • Female peahens prefer to mate with males with greater number of eyespots in their tail feathers

26. The benefits of mate choice for the female • 1. The male that provides the best offspring care • 2. The male that provides the best territory • 3. The male that provides the best genes • The typical number of mates an animal has during its breeding season is called themating system • Monogamy – One male and one female • Polygyny – One male and many females • Polyandry – One female and many males • Polygyny is more common than polyandry

27. An animal’s reproductive strategy involves “decisions” regarding the following • The choice of mates • The number of mates • The time and energy to devote to rearing offspring (parenting) • The two sexes of a species often have different reproductive strategies • In most animal species, females exercise more mate choice and parental investment

28. Fire ants Fig. 33.11 33.11 Communication Within Social Groups Many insects, fish, birds and mammals live in social groups • Communicated information includes • Alarm calls indicate predators • Alarm pheromones trigger attack behavior • Trail pheromones organize cooperative foraging

29. Fig. 33.12 • European honeybees use a very complex dance language to direct hivemates to rich nectar sources • A scout returning from a foraging trip performs a waggle dance that resembles a figure eight • The direction of the food source relative to the direction of the sun is indicated by the angle of the straight run • The distance to the food source is indicated by the tempo, or degree of vigor, of the dance

30. Fig. 33.13 Primate language • Some primates have a “vocabulary” that allows individuals to communicate the predator identity • The vocalizations of African vervet monkeys distinguish between leopards and eagles • Each distinctive call elicits a different and adaptive escape behavior

31. All of the roughly 3,000 human languages draw from the same set of 40 consonant sounds • Language develops at an early age in humans • Individuals who have not heard certain consonant sounds as infants can only rarely produce them as adults • Language acquisition goes through several stages • “Babbling” • Vocabulary of thousands of words • Simple sentences that convey information • Learning the rules of grammar • Nonverbal communication includes “body language”

32. Fig. 33.14 Meerkat 33.12 Altruism and Group Living • Altruism is the performance of an action that benefits another individual at a cost to the actor • Helpers at the nest in some bird species • Sentinels that give predator-alarm calls in some mammalian species • The existence of altruism among animals is rather perplexing • Natural selection should operate against it

33. Altruistic behavior may not be truly altruistic after all • The actor may benefit • Nest helpers may get parenting experience or inherit territory • Sentinels may be able to escape predators in the confusion following the alarm call • Individuals may benefit directly if there is a mutual exchange of altruistic acts • In reciprocal altruism, “cheaters” (nonreciprocators) are discriminated against • These individuals are cut off from receiving future aid

34. Fig. 33.15 • An altruist compensates for the reduction in its own reproductive success by increasing that of relatives • Selection that favors altruism directed toward relatives is called kin selection • The more closely related two individuals are, the greater the potential genetic payoff • White-fronted bee-eaters • Helpers tend to be close relatives • Helpers’ assistance increases with genetic relatedness

35. 33.13 Vertebrate Societies • Vertebrate social groups are usually less rigidly organized and cohesive than insect societies • Some vertebrate complex social systems exhibit both reciprocal and kin-selected altruism • However, vertebrate societies tend to display more conflict among members than insect societies • Conflict (and aggression) center on access to food and mates

36. Fig. 33.16 The organization of vertebrate societies is influenced by ecological factors such as food and predation • African weaver birds • Savanna-dwelling species build colonial nests • Have a polygynous mating system • Forest-dwelling species build solitary nests • Monogamous pairs form and cooperate to find limited food resources

37. Fig. 33.17 Naked mole rats are rare among vertebrates in that they form large organized societies • These underground colonies have a true division of labor • A single female or “queen” does all the breeding • Workers, consisting of both sexes, keep the tunnels clear and forage for food

38. 33.14 Human Social Behavior • Sociobiology is the study of the evolution of social behavior in animals • Pioneered by Edward O. Wilson, this field has proven highly controversial • No animal exhibits cultural differences to the degree seen in human populations • Both genetics and learning play key roles in complex human social behavior • However, the extent of each is hotly-debated