Animal Behavior (Ch. 51)

Behavioral Ecology

Two types of questions:

Proximate questions: Focus on environmental stimuli that trigger behavior and physiology behind response

“How?”

Ultimate questions: Focus on evolutionary significance of the behaviors

Why?”

Proximate Questions

Proximate questions address the mechanisms that produce a behavior.

The environmental stimuli, the genetic and physiological mechanisms that make it possible

Example- How does an animal carry out a particular behavior?

Red-crowned cranes breed in spring and early summer. Choose the proximate explanation:

A. Breeding is most likely to be successful in spring and early summer.

B. Increasing day length triggers the release of breeding hormones.

C. Ample food is available for chicks at this time.

Ultimate Questions

Ultimate questions address the evolutionary significance of a behavior

How a behavior increases the evolutionary fitness of the animal demonstrating it, helping it to survive and reproduce in its environment.

Example- Why does the animal show this behavior?

What is evolutionary fitness?

Adaptive behavior

An adaptive behavior increases an individual’s evolutionary fitness relative to other individuals in the population. (Similar to a physical adaptation)

Red-crowned cranes breed in spring and early summer. Choose an ultimate

explanation:

A. Breeding is most likely to be successful in spring and early summer.

B. Hormonal changes in the spring trigger breeding behaviors.

C. Breeding is triggered by the effect of increased day length on the birds’ photoreceptors.

Sexual cannibalism

In some species, one sex (usually the female) consumes the other during sexual reproduction.

Australian redback spiderPraying mantis Scorpion

Australian Redback Spider

Praying Mantis

Choose a proximate explanation for female cannibalism:

A. The female eats the male as he dangles his abdomen in front of her jaws.

B. The female can produce a larger egg sac if she eats the male.

C. The female gains nutrients by eating her mate.

Choose an ultimate explanation for female cannabilism:

A. The female eats the male because he dangles his abdomen in front of her jaws.

B. The female gains nutrients from eating the male.

C. The female copulates longer while eating her mate.

Choose a proximate explanation for male self-sacrifice:

A. The male’s somersault in front of the female’s jaws is triggered when he inserts a palp in the female’s sperm receptor.

B. The male is providing nutrients to his offspring.

C. A male that is cannibalized fathers twice as many offspring.

Choose an ultimate explanation for male self-sacrifice:

A. The male increases the length of copulation by sacrificing himself.

B. The male’s self-sacrifice is an innate, genetically programmed behavior.

C. The male is providing nutrients to his hungry mate.

Further testing…

- What experiment might you conduct that would narrow down the ultimate cause choices above?

Behavioral Ecology

Behavior= What an animal does and how the animal does it

Ethology= Study of how animals behave, particularly in their natural environment

Behavioral Basics

Behavioral Ecology

Based on idea that animals behave in such a way as to maximize fitness

Idea only works because genes influence behavior (nature)

Fitness= Passing on genes to offspring

Animals modify behavior to keep ratio of energy intake to energy expenditure high

Ex. chipmunks

Review: Optimal Foraging

Amount of food taken in will be in proportion to amount of energy spent

What is the relationship to fitness?

Scientific Research

EthologistsNikolaas Tinbergen

Nobel Prize- Eliciting behavior patterns in animals

Four Questions

Mechanical- How does the behavior occur?

Developmental- How has the behavior changed?

Evolution- How did this behavior come about?

Fitness- Why is this behavior beneficial?

EthologistsKarl von Frisch

Discovered the communication dance of bees

Round dance meant food was close

“Waggle” dance showed distance and direction of food

Dance of the Bees

Konrad LorenzWorked with greylag geese and discovered imprinting

https://www.youtube.com/watch?v=ihh1xBXwt_0

Ethnologists

Innate Behaviors

Fixed Action Pattern (FAP)

Sequence of unlearned, unchangeable behaviors

Usually carried to completion once started

Triggered by external event = sign stimulus

Ex. Stickleback fish- Tinbergen

Fixed Action Patterns

Tinbergen's Experiment

Fixed Action Patterns (FAP)

Egg rolling experiment

Directed MovementsTaxis

Change in direction

Automatic movement toward (positive taxis) or away from (negative taxis) a stimulus

Phototaxis

Chemotaxis

Geotaxis

Kinesis

Change in rate of movement in response to a stimulus

Complex Innate BehaviorsMigration

“Migratory restlessness” seen in birds bred & raised in captivity

Navigate by sun, stars, Earth’s magnetic fields

Imprinting- Innate & Learned

Learning to form social attachments at a specific critical period

Both learned and innate components

ImprintingGenerally irreversible

Has critical period/sensitive period = limited time when behavior can be learned

Ex. geese- Konrad Lorenz

Review• Optimal foraging• Scientists - Von Frisch, Lorenz, Tinbergen• Innate Behaviors

• FAP• Directed movements• Migration• Imprinting

Learned Behaviors

LearningModification of behavior based on experiences

Habituation= Lack of response to stimuli that give no information

Spacial Learning= Based on experience with structure of environment

Associative Learning= Connecting one event with another

Classical Conditioning

Operant Conditioning

Learning: Habituation“Cry wolf ” effect

Decrease in response to repeated occurrences of stimulus

Enables animals to disregard unimportant stimuli

Why?

Ex. falling leaves not triggering a response in baby birds

Spatial Learning • Memory reflected by environment’s spatial

structure • Ex. Digger wasps, hidden food sources, etc.

Associative Learning • Classical conditioning- Unconnected stimulus

associated with specific outcome • Ex. Pavlov’s salivating dogs and a bell

• Operant conditioning- Trial and error; behavior associated with specific outcome • Ex. Skinner’s mouse and food lever

Operant Conditioning

https://www.youtube.com/watch?v=H6LEcM0E0io

Social Behaviors

Social BehaviorsInteractions between individuals

develop as evolutionary adaptations

communication/language, agonistic behaviors, dominance hierarchy, cooperation, altruistic behavior

Agonistic BehaviorsThreatening & submissive rituals

symbiotic, usually no harm done

ex. territoriality, competitor aggression

Dominance HierarchySocial ranking with a group

pecking order

Cooperation

Working together in coordination

Ex. pack of African dogs hunting a wildebeest, white pelicans herding fish

Altruistic behavior

Reduces individual fitness, but increases fitness of recipient

Increasing survival of close relatives passes familial genes on to the next generation

Animal Signals

Visual

Auditory

Chemical

Tactile/touch