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TRANSCRIPT
BEHAVIOR
Chapter 22.1-22.4
Behavior
An organism’s conduct – the way it acts.
Partly the result of natural selection
Affects the ability of an individual organism to
survive and reproduce.
Successful behavior = live to produce many
offspring.
Studying behavior helps us to understand why
animals, including humans, act the way they do.
Stimulus & Response
Stimulus = anything that triggers a behavior.
External stimuli – stranger approaching
Internal stimuli - thirsty
Response = an organism’s reaction to a stimulus.
Dog barking
Drink water
Innate Behaviors
Innate behavior is influenced by genes, not based on experience.
Taxis (taxes) – change in direction of movement in response to a definite stimulus (planarian).
Always reacts the same way to same stimulus.
Kinesis – a response to stimuli but no particular response
Stimulus can also cause increased/decreased activity
Simple reflex – knee-jerk reflex.
Protects an organism from harm or helps it maintain normal conditions.
Instincts – inherited form of behavior that involves a whole series of reactions that do not require learning or practice.
Nest building in birds (search for good nesting sites, gathering materials, bringing materials to site, making particular type of nest).
Taxis in Planaria
Innate behaviors
Some innate behaviors do not change as a result of
experience.
Fixed-action patterns.
Raccoon washing food
Dog digging to bury bone
Learned Behaviors
Learned behavior develops as a result of
experience.
Imprinting – type of learning that requires little practice
but only occurs during a genetically determined time.
Duckling/goslings
Habituation – exposed to stimulus over and over, it may
lose it’s response or habituate
Train near home while sleeping
Learned Behaviors
Conditioning – one stimulus is associated with another unrelated stimulus.
Pavlov’s dog – bell rings, meat is presented. Bell rings, dog salivates.
Trial-and-error learning- an animal faced with two or more responses learns the one that leads to a reward.
Dog training with treats.
Good or bad tasting food
in nature.
Biological Aspects of Behavior
The nervous & endocrine system control behavior.
Genes affect development of brain.
Most human behaviors are influenced by genes and
environment.
Genetic determination of some behaviors…
Fruit fly foraging widely or close to home.
Honeybees expel diseased bees from hive.
Crickets have distinct chirp patterns.
Environmental & Cultural aspects of
behavior
Environment influences behavior
Choice of clothing
Individual differences
Cultural differences
Symbolic values
External and Internal stimuli influence
behavior
Courting behavior of birds/fish due to hormone levels
which are affected by temperature or time of day.
Symbiosis
relation where two species live closely together
Mutualism
(+/+)
Both organisms benefit (flower/insect)
Commensalism
(+/0)
one organism benefits/ other not affected (barnacles/whales)
Parasitism
(+/-)
one organism benefits, one organism is harmed
(Tapeworm/Human)
24.3 Guest Speaker
Noah Heilenbach
Symbiotic Relationships
Friday
24.6 Population Dynamics
Different factors limit the population of each
species
Population density = the # of individuals per unit of
land area or water volume.
Limiting Factors
Factors that limit the productivity of ecosystems
There may be one or several limiting factors in an
ecosystem – limiting factor for the desert is water,
limiting factor for ocean is iron, etc.
Limiting factors can also be biotic – prey can be a
limiting factor
Productivity – conversion of energy and nutrients
into growth
Exponential Growth
If all limiting factors were removed…
Exponential growth of organisms everywhere
Resources will run out and slow growth
Logistic Growth
When the population keeps growing and eventually
becomes stable.
Carrying Capacity – is the largest population of a
species the environment can support
Predator-Prey cycle
Variation in population size of one important
species can ripple through an entire ecosystem.
Boom and Bust cycle
When population exceeds the carrying capacity.
Can result population crash
Reproduction declines
Sharp increase in death rate
