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33.1 Approaches to the Study 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 - PowerPoint PPT Presentation
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The Living WorldFourth Edition
GEORGE B. JOHNSON
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PowerPoint® Lectures prepared by Johnny El-Rady
33 Behavior and theEnvironment
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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)
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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
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33.2 Instinctive Behavioral PatternsEarly research in animal behavior focused on patterns that appeared to be instinctive or innate
These are the same in all individuals of a speciesAppear 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
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Egg retrieval by geese
Examples of Innate Behavior
Behavior is triggered by a sign stimulus
Egg out of nestInnate releasing mechanism provides the neural instructions that detect stimulusA fixed action pattern is triggered
Intricate egg retrieval behavior
Fig. 33.2a
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Sign stimuli are often not very specific
Red color is the sign stimulus
Fish displayed aggressive postures when challenged with unfishlike models with red strips!
Male stickleback fish develop red coloration on their undersides during breeding season
React aggressively to approach of other males
Fig. 33.2b
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33.3 Gene Effects on BehaviorBehavioral genetics is the study of how genes influence behavior
Many behaviors are inherited in Mendelian fashionCrosses of two species showing different behaviors yields hybrids with “intermediate” behavior
A study of human twins revealed the followingIdentical twins separated at birth and raised apart developed many similarities in personalityFraternal twins raised together had personalities no more similar than those raised apart
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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
Fig. 33.3
Normal mother
Mother with two mutant fosB alleles
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33.4 How Animals LearnLearning is the modification of animal behavior as a result of previous experiences
Non-associative learningNo requirement for an association between two stimuli or between a stimulus and a responseSensitization
Repeating a stimulus produces greater response
HabituationDecrease in response to a repeated stimulus
Learning not to respond to a particular stimulus
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Associative learningInvolves formation of an association between two stimuli or between a stimulus and a response
The behavior is conditionedClassical conditioning
Paired presentation of two stimuli causes an animal to create an association between them
Pavlovian conditioningOperant conditioning
An animal learns to associate its behavioral response with a reward or punishment
Trial-and-error learning
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Fig. 33.4
Social attachments to other individuals that will profoundly influence behavior later in life
Imprinting
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
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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 soundsHowever, 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 memoryThese birds have a large hippocampus
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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
White-crowned sparrows that heard no song at all during rearing, had a poorly developed song as adults
Thus, song development involves both instinct and learning
Fig. 33.5
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33.6 Animal CognitionA 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 sandChimpanzees use twigs to probe entrance to termite nestSea otters bash clams against rocks to break them open
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There is also compelling evidence that animals can solve problems
Chimpanzees could not get to bananas by jumpingThey 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 itThis process was repeated until the food was within reach!
Fig. 33.6
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33.7 Behavioral EcologyThe study of animal behavior can be divided into
1) A study of its development2) A study of its physiological basis3) A study of its function
Behavioral ecology is the study of how natural selection affects behavior
Focuses on the adaptive significance of behaviorHow behavior may increase survival and reproductive success, or fitness
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33.7 Behavioral EcologyAdaptive traits confer evolutionary advantages in different ways
Some behaviors reduce predationEgg-shell removal by gulls reduce predation by crows
Other behaviors enhance energy intakeThis allows more offspring to be supported
Other behaviors increase resistance to diseaseStill others enhance the ability to acquire a mate
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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
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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
Thus, for a behavior to be favored by natural selection, the benefits have to outweigh the costs
However, a defensive cost is increased predation
Fig. 33.8
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33.9 Migratory BehaviorMany 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 geeseWarblersStarlings
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33.9 Migratory BehaviorCompass 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
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Fig. 33.9 Starlings learn how to navigate
Transport of captured birds
Flight of experienced birds
Flight of inexperienced birds
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33.9 Migratory BehaviorHow is the compass sense achieved?
Migrating birds detect the earth’s magnetic field and orient themselves with respect to itSun and stars may also be used for orientation
How is the map sense achieved?Recognition of certain cues, like the position of mountains and coastlinesMigration through featureless terrain presents more of a puzzle
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33.10 Reproductive BehaviorsReproductive behaviors encompass a variety of animal behaviors, including courtship
Competition for mating opportunities has been termed sexual selection
Intrasexual selectionCompetition between members of one sex (usually males)
Intersexual selection Essentially, mate choice
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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
Fig. 33.10
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The benefits of mate choice for the female1. The male that provides the best offspring care2. The male that provides the best territory3. The male that provides the best genes
The typical number of mates an animal has during its breeding season is called the mating system
Monogamy – One male and one femalePolygyny – One male and many femalesPolyandry – One female and many males
Polygyny is more common than polyandry
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An animal’s reproductive strategy involves “decisions” regarding the following
The choice of matesThe number of matesThe 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
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33.11 Communication Within Social Groups
Many insects, fish, birds and mammals live in social groups Communicated information includes
Alarm calls indicate predatorsAlarm pheromones trigger attack behaviorTrail pheromones organize cooperative foraging
Fig. 33.11
Fire ants
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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 runThe distance to the food source is indicated by the tempo, or degree of vigor, of the dance
Fig. 33.12
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Some primates have a “vocabulary” that allows individuals to communicate the predator identity
The vocalizations of African vervet monkeys distinguish between leopards and eagles
Primate language
Each distinctive call elicits a different and adaptive escape behavior
Fig. 33.13
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All of the roughly 3,000 human languages draw from the same set of 40 consonant sounds
Language develops at an early age in humansIndividuals 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 wordsSimple sentences that convey informationLearning the rules of grammar
Nonverbal communication includes “body language”
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33.12 Altruism and Group LivingAltruism is the performance of an action that benefits another individual at a cost to the actor
Helpers at the nest in some bird speciesSentinels that give predator-alarm calls in some mammalian species
Fig. 33.14 Meerkat
The existence of altruism among animals is rather perplexing
Natural selection should operate against it
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Altruistic behavior may not be truly altruistic after allThe actor may benefit
Nest helpers may get parenting experience or inherit territorySentinels 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
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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
Fig. 33.15
White-fronted bee-eatersHelpers tend to be close relativesHelpers’ assistance increases with genetic relatedness
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33.13 Vertebrate SocietiesVertebrate social groups are usually less rigidly organized and cohesive than insect societies
Some vertebrate complex social systems exhibit both reciprocal and kin-selected altruismHowever, vertebrate societies tend to display more conflict among members than insect societies
Conflict (and aggression) center on access to food and mates
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The organization of vertebrate societies is influenced by ecological factors such as food and predationAfrican weaver birds
Savanna-dwelling species build colonial nests Have a polygynous mating system
Fig. 33.16
Forest-dwelling species build solitary nests
Monogamous pairs form and cooperate to find limited food resources
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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
Fig. 33.17
Workers, consisting of both sexes, keep the tunnels clear and forage for food
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33.14 Human Social BehaviorSociobiology 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