Transcript Behavioral Biology Chapter 54

Behavioral Biology
Chapter 54
Approaches
• 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
Approaches
• 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 or nurture
Innate behavior
• 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
• Once pattern begins, it goes to
completion; even if the egg is removed
Innate Behavior
• Male stickleback fish will attack anything
with a red underside
– Does not need to be a fish
– Supernormal stimuli: given a
choice: animals respond to a larger
stimuli over a normal size stimuli
Behavioral Genetics
• Artificial selection data has shown that
behavioral differences among individuals
often result from genetic differences
• Genetics of learning
Behavioral Genetics
• Mice: fosB gene
• Determines whether female mice
nurture their young
– Both fosB alleles disabled: ignore
young
– Normal mothers: protective maternal
behavior
• Protein expressed by fosB activates
other enzymes and genes that affect
neural circuitry within the hypothalamus
Behavioral Genetics
• fosB present: mother
cares for her young
• fosB absent: young
are ignored and
eventually die
Behavioral Genetics
• Prairie voles are
monogamous
• Montane voles
mate and do not
work together to
raise young
• Different response to
oxytocin and
vasopressin
• Peptide receptor
sequence and
location in brain
different
Vasopressin receptor
Learning
• 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
Learning
• 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
– 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
Development of Behavior
• 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
Development of Behavior
• 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
Development of Behavior
a. Exposed to
own species
song during
development
b. Not exposed
to song
Orientation and Migratory
Behavior
• 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
Orientation and Migratory
Behavior
• 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
Orientation and Migratory
Behavior
Migratory
behavior of
starlings
Communication
• 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
Long-distance communication
– Pheromones: chemical messengers
• Sex attractant
• Males have sensory receptors
• Some insect pheromones can be
detected as far as 7km away
– Acoustic signals
• Vocal calls, wing clicking
– Light signals: firefly
Communication
Communication facilitates group living
The waggle dance of honeybees
Communication
• 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
• 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
Behavioral Ecology
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
Behavioral Ecology
Optimal foraging makes two assumptions
1. Natural selection will only favor
behavior that maximizes energy
acquisition if the increased energy
reserves lead to increases in
reproductive success
– Avoid predators
– Find mates
Behavioral Ecology
Optimal diet. The shore crab selects a
diet of energetically profitable prey
Behavioral Ecology
Territorial behavior secures resources
• Home range: where the animal lives
and forages; defends territory
• Defense against intrusion by other
individuals
• Birds sing or display to signal their
territory; energetically costly
• Benefit: increased food intake
Sexual 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...efficient strategies in a niche
Sexual Selection
Advantage of male
mate choice. Male
Mormon crickets
choose heavier
females as mates,
larger females have
more eggs
• Male Mormon crickets use 30% of their
body weight making up a
spermatophore (nutritive protein
containing packet) for the female
Sexual Selection
• Mating systems reflect adaptations
for reproductive success in a niche
• 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
• Mating systems influenced by ecology
– Territory size
– Needs of offspring
• Both parents: monogamy
• Altricial: offspring require long care
• Precocial: little care required
• Polyandrous systems: males usually care
for the young, females mate with 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
• Kin selection: direct genetic advantage;
selection favors relatives
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
Social Systems
Flocking behavior decreases predation
Social Systems
• Insect societies include individuals
specialized for different tasks
• Castes: groups of individuals that differ in
size and morphology and perform different
tasks
• Workers and soldiers
– Honeybees
– Leaf-cutter ants
– Fire ants