Animal Behavior

Mader: Biology 8th Ed.

Animal Behavior

Chapter 45


Outline• Genetic Basis

– Nature versus Nurture• Learning• Female Choice• Male Competition• Dominance Hierarchy• Territoriality• Communicative Behavior• Sociobiology and Animal Behavior• Altruism versus Self-Interest


Genetic Basis

• Two basic types of behavioral questions:– Mechanistic– Survival Value

• Both recognize behavior, observable and coordinated responses to environmental stimuli, has at least a partial genetic basis.– Genes influence development of neural

and hormonal mechanisms controlling behavior.


Nature or Nurture

• Nature (inherited) versus nurture (environmental) questions have been, and are still, constantly debated.– Studies on identical twins can be used to

determine extent of inherited behavior.Genetically identical twins raised

separately are sometimes remarkably similar.


Behavior Undergoes Development

• Some behaviors seem to be stereotyped.– Fixed Action Patterns (FAP’s)

Originally assumed to be elicited by a sign stimulus.

Increasingly thought to develop after practice.


Pecking Behavior of Laughing Gull Chicks


The Phenomenon of Learning

• Operant Conditioning– Gradual strengthening of stimulus-

response corrections.Trick-training in birds.

• Imprinting– Imitate behavior observed during sensitive

period.Goslings follow any moving object after

birth.


The Phenomenon of Learning

• Song Learning in Birds– Brain of a bird seems to be especially

primed to respond to acoustical stimuli during a sensitive period.

Social experience appears to have an even stronger influence over development of singing.


Behavior Is Adaptive

• Sexual selection refers to changes in females and males, often due to differential reproductive success, caused by mate choice and competition for mates.


Female Choice

• Courtship displays help males and females recognize each other for successful mating.– Good Genes Hypothesis

Females benefit from selective choice by securing sperm with good genes.

– Run-Away HypothesisFemales choose mates on the basis of

traits that make them attractive to females.


Male Competition

• Cost-benefit analyses have been conducted to determine if the benefit of access to mating is worth the cost of competition among males.– Positive effects (benefits) must outweigh

negative effects (costs) if the behavior is to continue.


Dominance Hierarchy

• Males and females have separate dominance hierarchies.– Higher-ranking individuals have greater

access to resources.Baboons form temporary consort pairs

with females. Males may monopolize estrous

females. Or may assist females or form

friendship groups to secure future matings.


Female Choice and Baboon Male Dominance


Territoriality

• Territoriality is protecting an area against other individuals.– Red Deer Stags (males) compete for

groups of hinds (females).Hinds only mate with one stag.

Harem Master must be large and powerful to fight off challengers.

Less body fat, thus may be more likely to starve in bad times, and have shorter life span.


Competition Between Red Deer Stags


Animal Societies

• Members of a society are organized in a cooperative manner that extends beyond sexual and parental behavior.

• Communicative Behavior– Chemical

Pheromones designate chemical signals that are passed between members of the same species.


Communicative Behavior

• Auditory– Faster than chemical communication.– Can be modified by loudness, pattern,

repetition, and duration.• Visual

– Used by species active during the day.Contests between males make use of

threat postures. Save energy by avoiding fighting.


Communicative Behavior

• Tactile– Occurs when one animal touches

another.Gull chicks peck at the parent’s beak in

order to induce the parent to feed them.Foraging honeybees return to the hive

and perform a waggle dance that indicates the distance and direction of a food source.


Communication Among Bees


Sociobiology and Animal Behavior

• Sociobiology applies the principles of evolutionary biology to the study of behavior in animals.– Assume individuals derive more

reproductive benefits than costs from living in a society.

Other advantages include predator avoidance, assistance in rearing offspring, and finding food.


Sociobiology and Animal Behavior

• Societal Disadvantages– Crowding

Resource allocation.Spread of disease.


Altruism versus Self-Interest

• Altruism is behavior that involves a reduction in direct fitness that may be compensated by an increase in indirect fitness.– Inclusive Fitness includes both personal

reproduction and reproduction of relatives.Genetic relatedness may underlie

many/most acts of apparent altruism.


Nest Helpers

• Green Wood-hoopoes– One breeding pair per flock.

Other sexually mature members may help feed and protect fledglings and protect the home territory.

Helper is contributing to survival of its own kin.

Helper is more likely than nonhelper to inherit parental territory.


Migratory Behavior in Blackcap Warblers


Feeding Behavior of Garter Snakes


Review• Genetic Basis

– Nature versus Nurture• Learning• Female Choice• Male Competition• Dominance Hierarchy• Territoriality• Communicative Behavior• Sociobiology and Animal Behavior• Altruism versus Self-Interest

Animal Behavior

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