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Animal Behavior

What is Behavior? Behavior

• everything an animal does & how it does it

• response to stimuli in its environment

Why Study Behavior?

Evolutionary perspective…

• part of phenotype

• acted upon by natural selection

• lead to greater fitness?

• lead to greater survival?

• lead to greater reproductive success?

Understanding Behavior

Causes of Behavior

Proximate cause:

“how” a behavior occurs or is modified based on its immediate interactions with the environment

Ultimate cause:

“why” a behavior occurs in context of natural selection

- how does behavior contribute to survival and reproduction

Male songbird what triggers singing? how does he sing? why does he sing?

Courtship behaviors in cranes how does day length influence breeding? why do cranes breed in spring?

BEHAVIOR: A male stickleback fish attacks other male

sticklebacks that invade its nesting territory.

PROXIMATE CAUSE: The red belly of the intruding male acts as

a sign stimulus that releases aggression in a male stickleback.

ULTIMATE CAUSE: By chasing away other male sticklebacks,

a male decreases the chance that eggs laid in his nesting

territory will be fertilized by another male.

Types of Behavior

Is it nature or nurture?

•Innate behavior: behavior performed correctly and in the same way by all individuals of a species, without previous experience (genetic cause)

- “built in”, not learned,

•Fixed Action Pattern (FAP): innate behavior that occurs as an unchangeable sequence of actions

- triggered by sign stimulus

- conducted to completion once started - ensures that activities essential to survival are performed correctly and without practice

The graylag goose responds to an egg outside her nest with a set of specific actions. Even when the egg is removed, the goose will continue to push at the air with her beak until she completes the FAP

Types of Behavior

Innate Behavior

Fixed Action Pattern

Sign Stimuli-

Attack on red belly stimulus

Court on swollen belly stimulus

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Types of Behavior Innate: Directed movements

Taxis

- change in direction

- automatic movement toward (positive taxis) or away from

(negative taxis) a stimulus

- phototaxis

-chemotaxis

Kinesis

- change in rate of movement in

response to a stimulus

Positive rheotaxis keeps trout facing into the current, the direction from which most food comes. Kinesis increases the chance that a sow bugs will encounter and stay in a moist environment.

Types of Behavior

Innate: Migration

•Regular, long-distance change in location

•Environmental cues: sun, stars, earth’s magnetic field, landmarks

monarchs

Circadian rhythm:

•Internal biological clock

• follows an approximately 24- hour natural cycle

The Suprachiasmatic nuclei (SCN) region is located in the hypothalamus of the brain. The SCN sends signals throughout the body in response to dark and light.

The circadian clock in the hamster brain signals a change in coat color according to season by releasing the hormone melatonin.

Plants can have two internal clocks: one sensitive to light and the other sensitive to temperature

Signal: stimulus that causes a change in behavior;

basis of animal communication

Pheromones – chemicals emitted by members of one species that affect other members of the species (eg. Queen bee, fruit fly, fish, termites, trees, humans)

• Visual signals – Warning flash of white of a mockingbird's wing

• Tactile (touch) – Male fruit fly taps female fly

• Auditory signals – screech of blue jay or song of warbler

Honeybee dance language

•bee returning from the field performs a dance to communicate information about the distance and direction of a food source

Minnows after alarm

Minnows before alarm

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Types of Behavior

Learned behaviors

• modified by experience

• variable, changeable

• flexible with a complex & changing environment

Interaction of Genes

and Experience

How does inheritance and experience form a particular behavior?

Biologists mated two different

species to form a hybrid species

Conclusion: hybrid offspring could alter inherited behavior based on experience.

Types of Learning

Learning: a change in an animal's behavior resulting from specific experiences

Types of learning:

1. Habituation: type of learning in which an animal stops responding to a repeated stimulus that conveys little or no important information

ex: ticking of a clock

2. Imprinting: learning that is limited to a specific time period in an animal's life and that is usually irreversible

learning + innate components

critical learning period : time period in which imprinting takes place

Lorenz: Greylag goose experiment

Control: mother rears young in nest

Experimental: Lorenz rears young in incubator

Result:

Control group: normal imprinting, followed mother, had normal goose relationships

Experimental group: imprinted on Lorenz, followed him, preferred human relationships to geese

BEHAVIOR: Young geese follow and imprint on their mother.

PROXIMATE CAUSE: During an early, critical developmental stage, the

young geese observe their mother moving away from them and calling.

ULTIMATE CAUSE: On average, geese that follow and imprint on their

mother receive more care and learn necessary skills, and thus have a

greater chance of surviving than those that do not follow their mother.

Types of Learning

3. Spatial Learning

• Cognitive Map: internal representation of spatial relationship among objects in an animal’s surroundings

Birds use spatial maps to relocate nut caches

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Some organisms move in response to a recognized object or environmental cue, a landmark.

t

No nest

Nest

4. Associative learning: learning to associate a stimulus with a consequence

•Classical conditioning - learning that a particular stimulus or a particular response is linked to a reward or punishment

- rat will push a level if it receives

food for pushing the level - predator avoids specific prey

associated with a painful experience

•Operant conditioning - trial & error learning - associate behavior with reward or punishment ex: learning what to eat

Pavlov’s dogs

Insight: the ability to respond appropriately to a new situation without previous experience

5. Cognition: process of knowing that involves awareness, reasoning, recollection, judgment

• Problem-solving behavior relies on cognition

6. Social learning: learning by observing others

Monkeys learn correct use of alarm calls

Selection for individual survival and reproductive success can explain most behaviors

Foraging: food-obtaining behavior • Recognize, search for, capturing, and consuming food

• Minimize costs / Maximize benefits

• Costs- energy expenditure and the risk of being eaten

• Crow will drop a whelk (a mollusc) from a height to break its shell

• Trade-off between the height and the number of times it must drop

• Researchers determined total flight height (energy) was minimized at 5 m Average crow flight height: 5.23 m

Mating Behavior & Mate Choice

Sexual selection: seeking and attracting mates, choosing and competing for mates

paternal care by male jawfish

Monogamous species

Polygynous species

Polyandrous species

Promiscuous Monogamous Polygamous (polygynous)

Polyandry

Partners Many One 1 M + many F 1F + many M

Structure Showy Similar Showy male Showy female

Care None Much Male = little Male = none

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Sexual seletion: ornaments correlate in general with health

and vitality

Courtship ritual: elaborate behavior of individuals of the same species before mating

Mate Choice

Males

Agonistic behavior: threats, rituals, and sometimes combat; settles disputes over resources

Females

Mate Choice Copying: copy the mate choice of others

Social Behaviors Competitive Behaviors (pack animals)

• Aggressive behavior: symbolic threat display or a physical struggle between individuals of the same species

• Dominance hierarchy : ranking of individuals in a group based on aggressive behavior

• Territorial behavior: behavior that protects territorial rights

ex: chatting squirrels

marking areas with urine

Genetic Basis of Behavior

• Certain behaviors in prairie voles are under relatively strong genetic control

• ADH (vasopressin) triggers pair-bond formation and aggression by male voles

Differences in oxytocin (a hormone) receptors in 2 species of voles

High oxytocin levels in

prairie voles

(monogomous)

Low oxytocin levels in

montane voles

(promiscuous)

Altruistic Social Behavior

Altruism : selfless behavior

Reduce individual fitness but increase fitness of others in population

i.e. bee societies; naked mole rats

• Inclusive fitness: total effect of producing own offspring (pass on genes) + helping close relatives

• Kin selection: type of natural selection; altruistic behavior enhances reproductive success of relatives

Altruism can be explained by inclusive fitness

Hamilton’s Rule and Kin Selection: quantitative measure for predicting when natural selection would favor altruistic

acts among related individuals

Benefit to the recipient (B)

Cost to the altruistic (C)

Coefficient of relatedness: fraction of genes shared; r

Hamilton’s rule: rB > C

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Example:

Assume the average individual has two children.

As a result of the sister’s action:

• The brother can now father two children, so B 2

• The sister has a 25% chance of dying and not being able to have two children, so C 0.25 2 0.5

• The brother and sister share half their genes on average, so r 0.5

If the sister saves her brother rB ( 1) C ( 0.5)

Game Theory (tit for tat strategy)

- Individuals always cooperate on first encounter

- An individual treats another the same way it was treated the last time they met

• individuals will always cooperate, unless their opponent cheated them the last time they met

• reciprocal altruism

Individuals who engage in a tit-for-tat strategy

have a higher fitness than individuals

who are always selfish

Evolution and Human Culture

• No other species comes close to matching the social learning and cultural transmission that occur among humans

• Human culture is related to evolutionary theory in the distinct discipline of sociobiology

• Human behavior, like that of other species, results from interaction between genes and environment

• However, our social and cultural institutions may provide the only feature in which there is no continuum between humans and other animals

Study for the test!