BEHAVIOR

• Is what an organism does, and why it does that (usually associated with animals)

• Is assumed to increase fitness (ultimate causation)

• Occurs in response to some stimulus (proximate causation)

Example 1: Bluegill behavior

• Bluegills breed in spring or early summer

• Ultimate causation: breeding is most successful when temperatures and food supplies are optimal

• Proximate: Breeding is triggered by the effect of the increased day length on the pineal gland

Example 2: Human sweet tooth

• Ultimate causation: sweet, high-energy foods were rare prior to mechanized agriculture

• Proximate: sweet taste buds increase the chance of eating high energy foods

NATURE VS. NURTURE

• THAT old argument! It’s finally been agreed that both contribute to behaviors

• The degree of each is still questioned by some, but the “smart scientist” (tee-hee) gives each about 50%

• Behaviors display a range of phenotypes which the genotypes expressed

(continued)

• Environmental factors affecting behavior: the chemical environment of the cell, hormonal and physical conditions, and interactions with other organisms, to name a few

INNATE BEHAVIOR

• Is present at birth but needs an environment in which to be expressed

• Is considered fixed if they are not influenced by environment or individual differences

• Ethology (1930s): study of animals in their environment (before behavior bio existed)

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• Was an attempt to understand now a variety of animals behaved in their natural habitats

Hosie’s question: What would be the single most difficult part of getting reliable observations in such a study?

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• Developed the concept of a fixed action pattern—a sequence of behaviors that are essentially unchangeable and usually carried to completion once initiated

• A FAP is triggered by an external sensory stimulus called a sign stimulus– In many cases, the sign stimulus is some feature

of another species

Examples:

• Some moths fold their wings and drop to the ground the (FAP) in response to the ultrasonic signal put out by bats (the sign stimulus)

• In the male three-spined stickleback fish, the males will attack (the FAP) other males that invade his territory if it has a red belly (the sign stimulus is the red belly)

BEHAVIORAL ECOLOGY

• Emphasizes evolutionary hypotheses, which is emphasized by the study of behavior in an ecological context

• Because natural selection works on genetic variation (tons of it in nature!), we expect organisms to possess features that maximize their genetic representation in the next generation (recombination, mutation aside)

(continued)

• In plain English, we expect animals to behave in ways that maximize their fitness in the environment– Sexual selection tends to maximize healthy

offspring– Feeding behavior is likely to optimize net energy

gain– This is pretty much the definition of behavioral

ecology

COST/BENEFIT ANALYSIS OF FORAGING BEHAVIOR

• Obviously, feeding is essential to survival and reproductive success

• Foraging (feeding behavior) is a favorite item of study at both the proximate and ultimate levels among behavioral biologists

• Foraging behaviors directly linked to morphology

• BE’s use cost/benefit analysis to study proximate and ultimate causes of diverse foraging strategies

(continued)

• Generalists feed on a wide variety of items (sea gulls, bears)– Most do not choose food randomly, though it

may concentrate on a specific item if it is in abundance

– Requires the organism to develop a search image (set of key characteristics that will lead it to the desired object)

(continued)

• Specialists feed on one specific source, and may starve even if other similar items are presented– Their morphology and behavior is highly

specific to their one source of energy

(continued…again)

• Search images enable an animal to combine efficient short-term specialization but with the flexibility of generalization

• Optimal foraging favors animals choosing foraging strategies that maximize benefit and minimize cost (time and energy spent foraging ISN’T being spent doing other things)

--Is experienced-based behavior modification

--are various forms

--can affect innate behaviors (efficiency)

LEARNING

HABITUATION• Loss of responsiveness to stimuli that conveys

little or no information

• Why crows wait until the last minute before leaving their flattened fauna behind…

MATURATION

1. CHANGES IN INNATE BEHAVIORS NOT ALWAYS DUE TO LEARNING

2. MATURATION: ONGOING DEVELOPMENTAL CHANGES (I.E., BIRDS LEARNING FLIGHT)

ARE YOU MY MOTHER?

• Limited to a specific time in life

• Lorenz mothered graylag geese raised in the lab

• They did not know their own mother!

• Adults need to imprint on children as well

• Critical period is when imprinting occurs

ASSOCIATIVE LEARNING

• CLASSICAL CONDITIONING WAS MADE FAMOUS BY PAVLOV (STIMULUS VS. REWARD OR PUNISHMENT)

• OPERANT CONDITION IS TRIAL-AND-ERROR LEARNING (HOW MANY TIMES WILL YOU KISS A PORCUPINE?)

PLAY

• HAS NO APPARENT EXTERNAL GOAL

• MOVEMENTS CLOSELY ASSOCIATED WITH GOAL-DIRECTED BEHAVIORS

• “PRACTICE HYPOTHESIS”

• CHILDREN “HORSING AROUND” RESULTS IN SAME TYPE INJURIES SEEN IN OTHER SPECIES

ANIMAL COGNITION

• IS THE ABILITY OF THE NERVOUS SYSTEM TO PERCEIVE, STORE, PROCESS, AND USE INFORMATION GATHERED BY THE SENSORY RECEPTORS

• STUDIED BY COGNITIVE ETHOLOGISTS (STUDY OF AWARENESS, CONSCIOUSNESS)

COGNITIVE MAPS

• SOME ANIMALS FORMULATE INTERNAL REPRESENTATIONS (SPATIAL RELATIONSHIPS)

• ANIMALS HAVE AN “IMAGE” OF THEIR OF THEIR FORAGING AREAS

• TAXIS AND KINESIS MAY OCCUR WITHOUT INTERNAL REPRESENTATION

KINESIS

MOVEMENT WHICH INVOLVES A SIMPLE CHANGE IN ACTIVITY RATE IN RESPONSE TO A STIMULUS (SOWBUGS, WOODLICE)

DON’T MOVE TOWARD/AWAY, JUST STAY BECAUSE THEY SLOW DOWN THERE

TAXIS

MORE OR LESS AUTOMATIC MOVEMENT, TOWARD A POSITIVE OR AWAY FROM A NEGATIVE STIMULUS

MIGRATION BEHAVIORS

--REGULAR MOVEMENT OVER RELATIVELY LONG DISTANCES

MIGRATION (CONT.)

• ORIENTATION: ANIMAL DETECTS COMPASS POINTS, TRAVELS IN STRAIGHT LINE

• NAVIGATION: PRESENT LOCATION RELATIVE TO ELSEWHERE

Social Behavior & Sociobiology

• Sociobiology places social behavior in an evolutionary context– Social behavior: broadly defined as any kind of

interaction between 2 or more animals, usually the same species

– Aggression, courtship, cooperation and deception are part of the behavioral landscape of social behavior

– Has both costs and benefits to members of species that interact

SOCIOBIOLOGY

• Relatively new discipline which applies evolution as a foundation for interpretation of behavior

• Members of the same niche (among a population) have strong potential for conflict– This is especially true for species who maintain

pops. near the carrying capacity

• Behavior is considered cooperative when more individuals perform work more efficiently than an individual

• Most animals will still act in a way for maximum benefit of self (even at cost to other participant)

COMPETITIVE SOCIAL BEHAVIORS OFTEN REPRESENT CONTESTS FOR RESOURCES

Agonistic behavior: involves both threatening & submissive behaviors;determines the “winner”

Threat is often exaggerated, but no always

Includes much “ritual” (symbolic activity)

DOMINANCE HEIRARCHIES occur in groups maintained by agonistic behavior

Chickens are a prime example—pecking order (unfamiliar chickens respond w/ pecks)

An alpha is the highest ranked animal, omega the least

Wolves are another example-only alphas mate

Territoriality

Territory=an area an individual defends (usually excludes members of own species)

Used for feeding, mating, rearing young, or combinations of these

Is usually a fixed location, but size varies by species

Home range is not territory, and is usually not defended

Are established and defended through agonistic behavior

Natural selection does not always favor territoriality; it takes energy to defend one’s territory

Is usually directed at conspecifics (mating, resources)

“fair shares” often result in population crashes

Mating behavior relates directly to fitness

• Courtship– Most animals are not conscious of reproduction– Mating interactions are very complex in the

animal kingdom

• Courtship allows animals to chose mates from potential candidates– Females more discriminating than males– Females have greater parental investment

(continued)

• Eggs more costly to produce than sperm• Females expend more energy producing offspring• Sexual selection is a mechanism of natural selection

– Assessment helps animals select a mating partner

• Based on ability of mate to help rear or provide for offspring, usually

• May be based on genetic quality– Birds, some insects display in “leks” where females visit

to choose a mate most fit

o Basis for assessment is difficult to determine

o sometimes may simply be male-male com-petition

o sometimes certain males may display best qualities (secondary sex characteristics, showiness, etc)

Ritualized behavior

• may have evolved from something more direct

• male dance flies carry silk balloons carrying food

•Copulation occurs after female accepts balloon

Interactions depend on communication

• Displays (songs, dances, etc.)

• Pheremones (chemical [olfactory] signals)

• Honeybee “waggle” dance (which some scientists question evidence of the pattern)

ALTRUISTIC BEHAVIOR

• Altruism: decreases individual fitness but increases fitness of recipient– “unselfish” behavior– Ex: Belding ground squirrels warn of

predators, allowing others to escape, but identifying its own position; worker bees kill intruders to defend the queen, which results in their deaths

Inclusive Fitness

• The total effect an individual has on proliferating its genes by reproducing and by aiding other close relatives

• Coefficient of relatedness quantifies inclusive fitness

• Is a proportion of genes that are identical in 2 individuals due to common ancestors

• COR is 0.5 in siblings (50% match); 0.125 for cousins

• Higher COR is more likely to receive aid (kin selection)

Reciprocal Altruism

• Rare in all animals but humans• Some say altruism only occurs in humans• Debate rages about influence of biological

evolution vs. culture in humans• Avoidance of incest is the specific context

of this debate– Is adaptive, as inbreeding increases defective

allele frequencies

• humans as wells as many bird and mammal species avoid incest

• Is the aversion innate?

• Is it acquired by socialization?

• Can culture escape biology?

“Behavioral characteristics are expressions of genes favored by natural selection.”

--sparked the debate about the connection between biological evolution and culture

CULTURAL TABOOS ON INCEST

• Incest avoidance is adaptive because “inbreeding” may increase the frequency of genetic disorders

• Many species avoid it, and most human cultures forbid it

• So: is this an innate aversion or an acquired behavior

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• “Nurture” (learned) says that cultural taboo is unnecessary if the behavior is innate

• “Nature” (genetic) says that taboos are proximate mechanisms reinforcing avoidance behaviors that ultimately evolved because of its effect on fitness

• For additional test preparation, visit www.biology.com/campbell. Take the student practice test! Be sure to select a chapter before selecting multiple choice.