33.1 Approaches to the Study of Behavior

The Living WorldFourth Edition

GEORGE B. JOHNSON

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

PowerPoint® Lectures prepared by Johnny El-Rady

33 Behavior and theEnvironment


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)


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


Fig. 33.9 Starlings learn how to navigate

Transport of captured birds

Flight of experienced birds

Flight of inexperienced birds


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


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


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


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


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


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


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


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


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”


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


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


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


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


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


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


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

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33.1 Approaches to the Study of Behavior