Transcript ECOLOGY SPRING 2009 - Florida International University


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)

Innate behavior: instinctive, does not require
learning
◦ Preset paths in nervous system
◦ Genetic: fixed action pattern
Example: 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 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
Learning: Operant conditioning

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



Parent-offspring interactions
influence cognition and
behavior
Imprinting: formation of
social attachment to other
individuals or develop
preferences that will influence
behavior later in life
Filial imprinting: attachment
between parents and offspring
Konrad Lorenz
Noble 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
in 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
individual releases a behavior by another
individual
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, increase mating success,
decrease 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 1973shared with Lorenz
Focus on:
Development
Physiological basis
Function: 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 energy
acquisition if the increased energy
reserves lead to increases in
reproductive success i.e.
Avoid 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
Sexual Selection



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
Altruism



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
Social Systems


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