Animal Behavior

What is behavioral ecology? Behavioral ecology studies how

behavior is controlled and how it develops, evolves, and contributes to survival

Behavior is everything an animal does and how it does it

Ethology is the scientific study of how animals behave, especially in natural environments

Understanding Behavior Questions that must be asked to understand

any behavior: What is the mechanistic basis of the

behavior (chemical, anatomical, and physiological mechanisms)?

How does development of the animal, from zygote to mature individual, influence behavior?

What is the evolutionary history of the behavior?

How does the behavior contribute to survival and reproduction (fitness)?

Fixed Action Patterns One type of behavior studied by ethologists is the fixed

action pattern (FAP) An FAP is a sequence of unlearned behavioral acts that is

essentially unchangeable and, once started, is usually carried to completion Triggered by a sign stimulus (some external sensory

stimuli that triggers the behavior Example: Aggressive behavior in male stickleback fish in

response to the red underside of an intruder fish

The following models were used to induce aggressive behavior. The realistic model did nothing, but the shapes with red bottoms caused aggressive behavior

Imprinting Imprinting is a type of

behavior that includes both learning and innate components and is irreversible There is a limited phase in an

animal’s development which is the only time when certain behaviors can be learned (sensitive period)

Incubator-hatched goslings imprinted on scientist (Konrad Lorenz) during first few hours of life and followed him

Nature vs. Nurture? In biology, it’s not an either/or scenario Genes and the environment both influence

behavior Some behaviors can be altered based on the

environment (still set behavior, but the behavior changes based on changing external conditions)

Other behaviors are virtually identical in a population . . . regardless of external stimuli

Innate behavior is behavior that is developmentally fixed, regardless of the environment

Directed MovementsAnimal movements can have

substantial genetic influence (directed movements)Examples:

KinesisTaxisMigration

Directed MovementsKinesis: a simple change in

activity or turning rate in response to a stimulusExample: pillbugs live best in

moist conditions; they move around more in dry areas and less in moist/humid areasMore movement increases

likelihood they will encounter a moist area

Directed MovementsTaxis = a more or less

automatic, oriented movement toward or away from a stimulusExample: fish swimming

against the currentMigration

Animal Signals & Communication

Many interactions between organisms are a result of sending and receiving information that alters behavior

A signal is a behavior that causes a change in another animal’s behavior

Communication involves the transmission of, reception of, and response to signals between animals

Types of Communication Chemical Communication:

Pheromones – chemically emitted odors that may attract organisms from several kilometers away. Particularly important in reproduction behavior

Auditory Communication: Bird songs and insect songs are also

important in reproductionDrosophila males produce a

characteristic “song” by beating their wings

Environment & Genetics Environmental factors,

such as the quality of the diet, the nature of social interactions, and opportunities for learning can influence the development of behaviors in every group of animals Example: Variations in diet

led to rejection of mates in Drosophila

Learning (start here) Learning is the modification of behavior based on

specific experiences Learning has a large range of expression

From simple imprinting to “learn” to recognize a parent to extremely complex . . . i.e. AP Biology

Habituation: loss of responsiveness to stimuli that convey little or no information If you poke a hydra, it will contract into itself.

Yet, if you keep poking the hydra (not very nice), eventually it will ignore the stimuli if it is not harmed

Evolutionarily it is believed this prevents organisms from wasting energy on stimuli that are not pertinent to survival or reproduction

Learning Spatial Learning: the modification of

behavior based on experience with the spatial structure of the environment, including the location of nest sites, hazards, food, and prospective matesExample: Organisms being able to recognize

landmarksThis is a much more sophisticated form of

learning because it involves “learning” stimulus that may vary in an environment

Learning By putting together several landmarks in a spatial

learning scheme, organisms could traverse to a variety of different environmental locations

Another possibility is the use of cognitive maps, an internal representation of the surrounding environment with spatial relations to each other (a mental map) Sometimes it is difficult to determine if an

organism is using spatial learning or relying on a cognitive map

Associative Learning

Another type of learning has to do with an organism learning behaviors based on experiential factors

Associative learning is the ability of many animals to associate one feature of the environment with another Example: Associating eating one type of

insect with a bad taste

Types of Associative Learning Classical Conditioning

an arbitrary stimulus is associated with a reward or punishmentExample: Pavlov’s Experiment

Operant Conditioning “trial-and-error learning”

Example: Mouse eating distasteful caterpillar OR a coyote getting a face full of quills from a porcupine

Cognition & Problem Solving Some behaviors show more sophisticated levels

of learning Cognition is the ability of an animal’s nervous

system to perceive, store, process, and use information gathered by sensory receptors Cognitive ethology studies how an animal’s

nervous system and behavior interactExample: chimpanzees cracking open oil

palm nuts by observing an experienced chimpanzee performing the task

Natural Selection & Behaviorism The genetic components of behavior evolve

through natural selection Natural selection favors behaviors that increase

survival and reproductive success Foraging behavior – Balance between

benefits of nutrition and cost of finding food (predation, energy, etc.)Cost-benefit analysis

Mating systems and parental careMost animals are promiscuous (no strong pair-

bonding relationship)MonogamousPolygamous (usually single male with many

females)

Reasons for mating systems Finding mates, caring for young, and passing on

genetic traits are strong determining factors in mate selection

Monogamy is important in birds. It takes a lot of work to feed and care for young that are relatively helpless. Both male and female are needed to provide for young, so they stick together

Polygamy occurs when the young can care for themselves at a young age. Males seek to maximize reproductive success

There are many other factors that influence behavior

Sexual selection Reminder:

Intersexual selection: one sex chooses a mate based on some characteristic of the other sex (female usually makes the selection and males vie for selection)

Intrasexual selection: competition of one sex for mates (males fight each other to “win” a female)

Evolutionary impact A lot of male behaviors, or anatomical features, may be

due to intersexual selection Females choose traits and those traits become

selected forPeacock feathers, birdsong, long eyestalks in male

stalk-eyed flies Male behaviors, or anatomical features, may also be

due to intrasexual selection Agonisitic behaviors are ritualized competitions that

teach males to fight for mates

Altruism & Inclusive Fitness

Most social behaviors are selfish

Altruism = when an animal behaves in a way that reduces its individual fitness but increases the fitness of the other individuals in the population Example: squirrels alarm

call, worker bees Helps close relatives (children,

siblings, etc.), thereby increasing the individual’s genetic representation in the next generation (saving close relatives) – “inclusive fitness”

Reciprocal Altruism Sometimes animals will behave

altruistically to other animals that are not related

This behavior can be adaptive if it aids the animal in the future, reciprocal altruism Reciprocal altruism is rare in animals Limited largely to same species that live in

a social group, but not always related (chimpanzees)

Social Learning In addition to genetic and environmental

influences, learning can be influenced by social contact Social learning is learning from

observing the behaviors of others Social learning forms the roots of culture Mistakenly, we believe social learning

only occurs in humans. It may also occur in animal populations

Social Learning Example: Mate choice copying

Female guppies have been seen to mate with males that have been successful in attracting other females

Example: Alarm calls Monkeys learn different calls to symbolize different

predators (leopards, eagles, snakes) When young these calls are inaccurate (any bird may

be given the “eagle” call Yet, as they mature and “learn” to discriminate

species, their calls become more accurate

What about us? Biology is not limited to the study of just

animal behaviors Some scientists study how evolutionary

theory applies to human culture, sociobiology This field is highly controversial

Could be used to justify status quo human societies (caste systems)

Risk of oversimplification