N Way in Which an Organism Responds to Stimuli in Its Environment

Animal Behavior

Chapter 26

Behavior

n Way in which an organism responds to stimuli in its environment

n Ethology – study of behavior in natural environment

n (2) Aspects of Behavior

n Proximate causation – how the behavior works (sense organ picks up info and relays to brain)

n Ultimate causation- why behavior occurs – reflex occurs to prevent injury

Which is which?

n Male songbird sings:

n Testosterone binds to hormone receptors in brain of bird triggering production of song

n Singing to defend territory against other male birds and to attract a female to reproduce

Basic Vocabulary

n Sign stimulus – “signal” in environemnt that triggers a behavior

n Innate releasing mechanism - sensory mechanism within the organism that detects the “signal”

n Fixed action pattern – stereotyped action

n Transduction – converting energy in environment to a nerve impulse

Nature vs. Nuture

n Nature – genetic reason for behavior

n Nuture – environmental reasons for behavior

Learning

n Modification of behavior based on experience

n (2) Types

n Nonassociative Learning

n 1. Habituation – decrease in behavior due to stimulus having no positive or negative consequences

n 2. Sensitization – increased response to stimulus

Associative Learning

n 1. Classical Conditioning – pairing stimulus to form association

n 2. Operant Conditioning – associating behavior with reward or punishment

Instinct

n Innate predisposition toward forming associations

n Pigeons – can associate food with colors but not with sound; danger with sound, not colors

n In other words, what an animal can learn is biologically influenced – boundaries set by instinct

Innateness has evolved with adaptation

n Pigeon – seeds have color – no sound

n Rats forage at night – can’t assciate food with color – only odor

n Seed-storing birds – great spatial memory – large hippocampus – memory area of brain

Parent-Offspring Interactions

n Imprinting – social attachments between parent and offspring

n Sensitive or critical period – learned at specific time in life

There are proximate and ultimate causes for this type of behavior

Reproductive Behaviors

n Hormonally controlled

n Hormones released when conditions are most favorable for growth of young (temperature, food)

n Males – testosterone

n Females – estrogen

Courtship

n Stimulus response chain – behavior of one individual triggers behavior in another

n Species specific – key in reproductive isolation

n Anoles – dewlap movement of male stimulates hormone release and egg laying in female

n Pheromones

n Acoustical signals – bullfrogs, bird song

Pheromones

n Chemical signals

n Species specific

n Sex attractants

n Trail pheromones - ants

n Alarm pheromones – bees attack behavior

Other Behaviors

n Mobbing

n Alarm

n Less species – specific

Human Language

n Infant can babble all sounds found in all languages

n Become specific – lose ability to make nationality-based sounds – French “r”

Behavior Movements
Kinesis

n A kinesis

n Is a simple change in activity or turning rate in response to a stimulus

n Sow bugs

n Become more active in dry areas and less active in humid areas

Taxis

n A taxis

n Is a more or less automatic, oriented movement toward or away from a stimulus

n Positive taxis – towards

n Negative taxis – away

n Positive phototaxis = ?????

n Movement towards light

n Many stream fish exhibit positive rheotaxis

n Where they automatically swim in an upstream direction

Migration

n Long-range, two-way movement

n Orientation – follow a bearing

n Navigation – set and adjust a bearing, then follow it

n Experienced birds – navigate; inexperienced – orient

Cognition and Problem Solving

n Cognition is the ability of an animal’s nervous system

n To perceive, store, process, and use information gathered by sensory receptors

Problem solving can be learned

n By observing the behavior of other animals

Genetic and Environmental Interaction in Learning

n Genetics and environment can interact

n To influence the learning process

Foraging Behavior

n Optimal foraging theory

n Views foraging behavior as a compromise between the benefits of nutrition and the costs of obtaining food

Mating Systems and Mate Choice

n The mating relationship between males and females

n Varies a great deal from species to species

n In many species, mating is promiscuous

n With no strong pair-bonds or lasting relationships

n In monogamous relationships

n One male mates with one female

n In a system called polygyny

n One male mates with many females

n The males are often more showy and larger than the females

n In polyandrous systems

n One female mates with many males

n The females are often more showy than the males

n In species that produce large numbers of offspring – r-strategists

n Parental care

n Is little or absent

n is at least as likely to be carried out by males as females

K-Startegists

n Larger animals

n More parental care

n Fewer offspring

Agnostic Behavior

n Such competition may involve agonistic behavior

n An often ritualized contest that determines which competitor gains access to a resource

Altruistic Behavior

n The concept of inclusive fitness can account for most altruistic social behavior

n Many social behaviors are selfish

n Natural selection favors behavior

n That maximizes an individual’s survival and reproduction

Altruism

n On occasion, some animals

n Behave in ways that reduce their individual fitness but increase the fitness of others

n This kind of behavior

n Is called altruism, or selflessness

n In naked mole rat populations

n Nonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predators

Inclusive Fitness

n Altruistic behavior can be explained by inclusive fitness

n The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspring

Hamilton’s Rule and Kin Selection

n Hamilton proposed a quantitative measure

n For predicting when natural selection would favor altruistic acts among related individuals

n The three key variables in an altruistic act are

n The benefit to the recipient

n The cost to the altruist

n The coefficient of relatedness

n Is the probability
that two relatives
may share the
same genes

n Natural selection favors altruism when the benefit to the recipient

n Multiplied by the coefficient of relatedness exceeds the cost to the altruist

n This inequality

n Is called Hamilton’s rule

n Kin selection is the natural selection

n That favors this kind of altruistic behavior by enhancing reproductive success of relatives

Foraging Behavior

n Optimal foraging theory

n Views foraging behavior as a compromise between the benefits of nutrition and the costs of obtaining food