What do you understand by behavior?What do you understand by behavior?

Learning Animal cognition Migratory behavior Ecology Reproduction

Behavior: the way an animal responds to stimulus in its environment

Two components of behavior◦ Immediate cause◦Evolutionary origin

Proximate causation:“how” of behavior◦Measure: hormone level - testosterone◦ Impulse of nerve signal

Ultimate causation: “why” of behavior Determine how behavior influences reproductive

success or survival

Controversy: ◦ Is behavior determined by individual’s genes◦Or by learning and experience

Nature ((instinct) or nurture (experience)(experience)

Innate behavior: instinctiveinstinctive, does not require learning◦Preset paths in nervous system◦Genetic: fixed action patternExample: goose replacing an egg from her nest

Egg retrieval behavior is triggered by a sign stimulus

Innate releasing mechanism or fixed action pattern is the stereotyped act

Not very specific: anything round will trigger the goose’s reaction

Once pattern begins, it goes to completion; even if the egg is removed

Artificial selection data has shown that behavioral differences among individuals often result from genetic differences

Genetics of learning

Human twin study Identical twins: identical

genetically 50 sets, twins raised

separately◦ Similarity in personality,

temperament, leisure time activities

Indicates that genetics plays a role in determining behavior in humans,

Learning: altered behavior as a result of previous experiences

Nonassociative learning: does not require an animal to form an association between two stimuli or between a stimulus and response◦Habituation: decrease in response to a repeated

stimulus◦No positive or negative consequences

Associative learning: association between two stimuli or between a stimulus and a response

◦Conditioned behavior through association◦ Two major types:

Classical conditioning Operant conditioning

◦Differ in the way associations are established

Classical conditioning: the paired presentation of two different kinds of stimuli with an association formed between them◦ Ivan Pavlov:◦ Pavlovian conditioningPavlovian conditioning

Unconditioned stimulus: meat

Unconditioned response: salivating

Conditioned stimulus: bell ringing

Conditioned response: After time, the dog salivates with only the ringing of the bell

animal learns to associate its behavior response with a reward or punishment◦ B.F. Skinner◦ Trial and error learning

Today it is believed that instinct guides learning by determining what type of information can be learned through conditioning

Learning: Operant conditioning

Parent-offspring interactions influence cognition and behavior

Imprinting:Imprinting: formation of social attachment to other individuals or develop preferences that will influence behavior later in life

Filial imprinting:Filial imprinting: attachment between parents and offspring

Konrad LorenzNoble Price 1973

Instinct and learning may interact as behavior develops

◦ White-crowned sparrow males sing species-specific courtship song during mating

◦ Genetic template: innate program to learn the appropriate song

◦ Can not learn the song unless they hear it at a critical period critical period in developmentin development

Chimps pull the leaves of off a tree branch to use it as a tool for picking termites

Some birds learn to take off milk caps from bottles

Orientation: goal-oriented movements◦ Track stimuli in the environment◦Homing instinct◦ Taxis: movement toward or away from a

stimulus◦Kineses: more or less active when

stimulus intensity increases

Migration involves population moving large distances: Monarch butterflies fly from North America to Mexico

Migrating animals must be capable of orientation and navigation

Navigation: the ability to set or adjust a bearing ◦Sun and stars: general direction◦Earth’s magnetic field: specific

path◦ Information from the stars

overrides the magnetic information if they conflict

Communication can play a key role in behaviors◦Among members of the same species◦Between species

Successful reproduction depends on appropriate signals and responses◦Stimulus-response chain: behavior of one behavior of one

individual releases a behavior by another individual releases a behavior by another individualindividual

Communication facilitates group living◦ Guards: set off an alarm call so group can

seek shelter◦ Social insects produce pheromones that

trigger attack behavior◦ Ants deposit trail pheromones between nest

and food source

Primate language:Vocabulary to communicate identity of specific predators

Chimpanzees and gorillas can learn to recognize a large number of symbols and use them to communicate abstract concepts

Complexity of human language◦ Differences are superficial◦ 3000 languages draw from the same

set of 40 consonant sounds

Behavioral ecology: study of how natural selection shapes behavior◦Adaptive significance of behavior◦Reproductive success, fitness

Questions asked◦ Is behavior adaptive◦How is it adaptive

Enhance energy intake, Enhance energy intake, increase mating successincrease mating success, , decrease predationdecrease predation

Evolutionary analysis: survival value of behavior

Tinbergen observed gull nestlings hatch and parents remove the shells of the eggs

Placed broken eggs by the nests◦ Predators (crows) found nests

with broken eggs and ate the hatchlings

◦ Nests without egg shells had less predation

Nobel Price 1973- shared with Lorenz

Focus on:DevelopmentPhysiological basisFunction: including evolutionary significance

Foraging behavior can directly influence individual fitness

Foraging involves a trade-off between food’s energy content and the cost of obtaining the food

Optimal foraging theory: natural selection favors individuals whose foraging behavior is energetically efficient

Optimal foraging assumes that:Behavior maximizes energyBehavior maximizes energy

acquisition if the increased energy reserves lead to increases in reproductive success i.e.Avoid predators, Find matesAvoid predators, Find mates

Optimal behavior has evolved by natural selection

Reproductive strategies: decisions about mating

◦How many mates to have◦How much time devoted to rearing offspring◦How much energy devoted to rearing offspring

Evolved partly in response to cost of reproduction

Mating systems reflect adaptations for reproductive success

Energy costs, food resources, nest sites, distribution of opposite sex

Mating systems◦Monogamy: one male one female◦Polygyny: one male many females◦Polyandry: one female many males

Sexual Selection

Altruism: the performance of an action that benefits another individual at a cost to the actor

Question: if altruism imposes a cost to an individual, how could an allele be favored by natural selection?

Group selection: rare◦Among groups: leads to a decrease in allele’s frequency◦Within groups: may favor the allele

Altruism

Society: a group of organisms of the same species that are organized in a cooperative manner

Advantages◦Kin selection: greater odds of alleles surviving in the

gene pool◦Greater protection from predators◦ Increase feeding and mating success

Social Systems