Transcript Chapter 27: Animal Behavior

Chapter 27: Animal Behavior
What is behavior?
• The response an organism or group of organism’s have
towards their environment is called “behavior.” In the wild
there is both group behavior and individual behavior.
• Example of individual behavior: hunting, mating calls,
sleeping habits, etc.
• Example of group behavior: migrating, flocking, schools of
fish, etc.
Chapter 27: Animal Behavior
Behavior lets organisms respond rapidly and
adaptively to their environment. Usually in a beneficial
way.
Examples?
Plant bends
toward light
Cat comes
when you
use a can
opener
Pufferfish inflates
when threatened
Toad releases
poison when
grabbed
Chapter 27: Animal Behavior
Why is behavior important and how does it work?
• Detecting and responding to stimuli is key to an individual’s
survival. There are two types of stimuli:
• Internal stimuli tell an animal what is occurring in its own
body.
– hunger
– thirst
– pain
Chapter 27: Animal Behavior
• External stimuli give an animal information about its
surroundings.
– sound
– sight
– changes in day length or temperature
Chapter 27: Animal Behavior
• Specialized cells that are sensitive to stimuli detect sensory
information.
– information is transferred to the nervous system
– nervous system may activate other systems in response
• Animal behaviors help to maintain homeostasis.
Chapter 27: Animal Behavior
Turn to your neighbor: Review! What are the types of cells
found within the nervous system?
Chapter 27: Animal Behavior
• There are two examples of movement-related behaviors:
– Kinesis is an increase in random movement.
Example: Pill bugs increase activity as they dry out to find moist
areas
– Taxis is movement in a particular direction either
toward or away from a stimuli
–Example: plants growing toward light, deer running
away from rustling in the brush
Chapter 27: Animal Behavior
Why do particular behaviors occur? Internal and external
stimuli usually interact to trigger specific behaviors.
• Most behaviors are a response to both internal and external
stimuli
– Combination, not just one stimuli
• External stimuli may trigger internal stimuli.
• Green anole reproductive behavior is triggered by internal
and external stimuli.
– External: males become aggressive and court females
– Internal: females release hormones that make females
receptive
Chapter 27: Animal Behavior
Turn to your neighbor: How could internal and external
stimuli cause you to wake up in the morning?
Chapter 27: Animal Behavior
Some behaviors occur in cycles.
• A circadian rhythm is the daily cycle of activity.
– occurs over a 24-hour period
– run by a biological clock
Chapter 27: Animal Behavior
• Turn to your neighbor: Turn to your neighbor: When
people travel, they often complain that the jet-lag is
messing with their “Circadian Rhythm.” Explain what
they mean.
Chapter 27: Animal Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– During hibernation, an animal enters a seasonal dormant
state.
Chapter 27: Animal Behavior
• Turn to your neighbor: What kind of stimuli might trigger hibernation?
Chapter 27: Animal Behavior
• Behaviors may occur daily, monthly, seasonally, or annually.
– During hibernation, an animal enters a seasonal dormant
state.
– During migration, animals move seasonally from one
portion of their range to another.
Chapter 27: Animal Behavior
• Turn to your neighbor: Is migration an individual or group behavior?
Chapter 27: Animal Behavior
Nature vs. Nurture
Both genes and environment affect an animal’s behavior.
Chapter 27: Animal Behavior
What is an “instinct” ?
• An instinct is a complex
inborn behavior.
• Instinctive behaviors share
several characteristics.
– innate, or performed
correctly the first time
– relatively inflexible
– Why would instincts be
necessary?
– Baby Swimming Reflex
Chapter 27: Animal Behavior
Many behaviors have both innate and learned
components.
• Learning takes many forms.
• Imprinting is an example of learned behavior.
• Imprinting: when an organism copies behavior they
observe, usually shortly after their birth
• Example: Graylag geese imprint 12 hours after hatching:
they learn to follow around their parents. Scientists who
work with these geese have to be careful not to let
hatchlings imprint on them instead of their geese parents.
Chapter 27: Animal Behavior
Turn to your neighbor: Why might this person be wearing
a goose costume?
Chapter 27: Animal Behavior
• Imitation: When organisms copy behaviors they see
displayed by others
– young male songbirds
learn songs by listening
to adult males
– Children learning to talk
– snow monkeys and
potato-washing
behavior…younger
teaches older
Chapter 27: Animal Behavior
Conditioning
• The behavior of an organism is not constant: it can change
depending on the organism’s surroundings. Conditioning
describes the way an organism’s behavior changes based
on whether the behavior results in a positive or negative
outcome. There are two types of conditioning:
Chapter 27: Animal Behavior
– Classical conditioning: previously neutral stimulus
associated with behavior triggered by different stimulus
– Ivan Pavlov and salivating dog
Chapter 27: Animal Behavior
– Operant conditioning: behavior increased or decreased
by positive or negative reinforcement
– B.F. Skinner and “Skinner boxes”
Chapter 27: Animal Behavior
• Turn to your neighbor: Explain how bells are used to
condition student behavior.
Chapter 27: Animal Behavior
All behaviors have benefits and costs
• The benefits of a behavior are increased survivorship (# of
individuals that survive from one year to the next) and
reproduction rates.
– both increase an individual’s fitness; favored by natural
selection
– both have costs
Chapter 27: Animal Behavior
• Behavioral costs can be divided into three categories.
– energy costs: energy not available for other tasks
– opportunity costs: time spent cannot be used on another
task
– risk costs: need food but risk getting eaten
Some
behaviors
seem
harmful but
are
beneficial
Chapter 27: Animal Behavior
• Turn to your neighbor: If a song-bird spends an entire day
trying to attract a mate, what is one opportunity-cost of this
behavior?
Chapter 27: Animal Behavior
Animals perform behaviors whose benefits outweigh their
costs.
• Behaviors evolve only if they improve fitness.
• Territoriality refers to the control of a specific area.
Chapter 27: Animal Behavior
Living in groups also has benefits and costs.
• Social behaviors evolve when the benefits of group living
outweigh its costs.
– benefits: improved
foraging, reproductive
assistance, reduced
predation
– costs: increased
visibility, competition,
disease contraction
• Group living requires learning social structure and
membership.
Chapter 27: Animal Behavior
Are humans more intelligent than other animals?
• Insight is the ability to solve a problem mentally without
repeated trial and error.
– observed in primates, dolphins, and corvids
– chimpanzee retrieving hanging bananas
Chapter 27: Animal Behavior
Cognitive ability may provide an adaptive advantage for
living in social groups.
• Intelligence in animals seems to be correlated with two
characteristics.
1. relatively large brains for their body size
2. live in complex social groups
Chapter 27: Animal Behavior
• Cultural behavior spreads through a population by learning,
not by selection.
– taught to one generation by another
– aided by living in close proximity