Transcript chapter39_Sections 1

Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 39
Animal Behavior
(Sections 39.1 - 39.4)
Albia Dugger • Miami Dade College
39.1 An Aggressive Defense
• Bee stings are highly painful and even a single sting can be
fatal to someone allergic to honeybee venom
• Africanized bees respond aggressively to chemical alarm
signals (pheromones); they attack in great numbers, sting
with little provocation, and pursue intruders persistently
• pheromone
• Intraspecific chemical communication signal
Hybrid Africanized Honeybees
Ecology
• Scientists investigate proximate causes of behavior (genetic
and physiological factors) and ultimate causes (environmental
factors that favored evolution of a behavior)
• Interactions among organisms and their environment are part
of the study of ecology
• ecology
• Study of organism–environment interactions
39.2 Behavior’s Genetic Basis
• Animal behavior requires a capacity to detect stimuli
• Structure of the nervous system determines the types of
stimuli an animal can detect, and types of responses it can
make
• stimulus
• Environmental cue that a sensory receptor responds to
How Genes Can Influence Behavior
• Much variation in behavior within or among species results
from inherited differences
• Behavior can be influenced by genes that affect the structure
and activity of the nervous system, and by genes that affect
metabolism or physical traits
• Example: Genes that specify beak structure in African
seedcrackers determine which species eat large seeds and
which species eat small seeds
Genetic Variation Within a Species
• One way to investigate the genetic basis of behavior is to
examine behavioral and genetic differences among members
of a single species
• Example: Garter snakes of the Pacific Northwest
• Snakes in coastal forests prefer to eat banana slugs that
are common on the forest floor
• Snakes that live inland prefer to eat fishes and tadpoles
• When offered a slug, newborn offspring of coastal snakes
ate it, but offspring of inland snakes ignored it
• Newborn coastal snakes associate slug scent with food
Coastal Garter Snake and Banana Slug
Genetic Variation Within a Species (cont.)
• Example: Fruit fly larvae eat yeast on decaying fruit
• 70% are “rovers” (move as they feed)
• 30% are “sitters” (stay in one place)
• The proximate cause of different behaviors is the gene
foraging, which encodes an enzyme for olfactory cues
• Dominant allele = rover phenotype
• Homozygous recessive = sitter phenotype
• The ultimate cause of behavioral variation is natural selection:
a rover does best when surrounded by sitters, and vice versa
“Rovers” and “Sitters”
• Genetic polymorphism for foraging behavior in fruit fly larvae
“Rovers” and “Sitters”
yeast
A Rovers (genotype FF or Ff )
move often as they feed. When
a rover’s movements on a petri
dish filled with yeast are traced
for 5 minutes, the trail is
relatively long.
B Sitters (genotype ff ) move
little as they feed. When a
sitter’s movements on a petri
dish filled with yeast are
traced for 5 minutes, the trail
is relatively short.
Fig. 39.3, p. 658
Genetic Variation Among Species
• Comparing behavior of related species can clarify the genetic
basis of a behavior
• Example: In voles, inherited differences in hormone receptors
influence mating and bonding behavior
• Most voles are promiscuous, some are monogamous
• Brains of monogamous species have many receptors for
the hormone oxytocin
• Also, males of monogamous species have more arginine
vasopressin (AVP) receptors
Voles
• Vole species vary in
mating and bonding
behavior, and in the
number and distribution
of receptors for the
hormone oxytocin
Oxytocin Receptors in Vole Brains
• Monogamous
• Promiscuous
Human Behavior Genetics
• Most human behavioral traits have a polygenic basis and are
influenced by the environment
• Effects of a single gene among many may show a small
statistical correlation between a particular allele and an
increased tendency toward a particular human behavior
• Animal studies sometimes inspire human studies:
Investigators are looking at possible connections between
oxytocin and autism, a disorder involving social attachments
Key Concepts
• Genetic Foundations
• Genes that affect the ability to detect stimuli or to respond
to nervous or hormonal stimulation influence behavior
• Studying behavioral differences within and between
species allows scientists to determine the behavior’s
proximate and ultimate causes
ANIMATION: Hormonal Control of Behavior
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
39.3 Instinct and Learning
• All animals are born with the capacity for instinctive
behavior – such as the newborn coastal garter identifying a
banana slug as food
• instinctive behavior
• An innate response to a simple stimulus
Instinctive Behavior: Cuckoos
• A female cuckoo lays her eggs in nests of other birds
• When a cuckoo egg hatches, contact with other eggs
stimulates a fixed action pattern: the blind hatchling shoves
the eggs out of the nest, eliminating the competition
• fixed action pattern
• Series of instinctive movements elicited by a simple
stimulus and carried out with little variation once begun
Cuckoos (cont.)
• Instinctive behavior: A
young cuckoo shoves
its foster parent’s eggs
out of the nest
Cuckoos (cont.)
• The cuckoo’s foster
parent responds to the
simple stimulus of a
chick’s gaping mouth
with the fixed action
pattern of parental
feeding behavior
Time-Sensitive Learning
• A genetic capacity to learn, combined with actual experiences
in the environment, shapes most forms of behavior
• Learning may occur throughout an animal’s life, or be
restricted to a critical period
• learned behavior
• Behavior that is modified by experience
Time-Sensitive Learning (cont.)
• Imprinting is a form of learning that occurs during a
genetically determined time period early in life
• Example: Baby geese follow the large object that bends over
them in response to their first peep – usually their mother
• imprinting
• Learning that can occur only during a specific interval in
an animal’s life
Imprinting
• Nobel laureate Konrad Lorenz with geese that imprinted on
him, and a normal imprinting pattern
Time-Sensitive Learning (cont.)
• Example: Songbirds
• A male songbird recognizes his species’ song when he
hears older males singing it
• Males reared with no model sing a simplified version of
their species’ song
• Many birds can only learn the details of their speciesspecific song during a limited period early in life
Conditioned Responses
• Most animals are lifelong learners:
• They learn to associate certain stimuli with rewards and
others with negative consequences
• Classical conditioning:
• An involuntary response to a stimulus becomes
associated with a stimulus that accompanies it
• Example: Pavlov’s dog salivated at the sound of a bell
associated with feeding time
Conditioned Responses (cont.)
• Operant conditioning:
• An animal modifies its voluntary behavior in response to
consequences of that behavior
• Example: A rat that presses a lever and is rewarded with
food presses the lever again; a rat that receives a shock
when it enters a particular area avoids that area
Other Types of Learned Behavior
• Habituation:
• An animal learns by experience not to respond to a
stimulus that has neither positive nor negative effects
• Example: Pigeons in cities learn not to flee from people
who walk past them
• habituation
• Learning not to respond to a repeated stimulus
Other Learned Behavior (cont.)
• Spatial learning:
• Animals learn about landmarks in their environment that
help them return home
• Social learning:
• Animals learn to recognize offspring, competitors, or
mates by appearance, calls, odor, or combinations of cues
• Observational learning:
• Animals learn skills by imitating behaviors it observes in
others
Social Learning
• Male lobsters battle at their first meeting – the loser will
remember the winner’s scent and avoid him
Observational Learning
• A marmoset opens a container using the same method he
observed another use
Key Concepts
• Instinct and Learning
• Instinctive behavior can be performed without any practice
• Most behavior has a learned component
• Even instinctive behavior is often modified over time
• Some learning can only occur during a certain portion of
the lifetime
Video: Ducklings Following
Video: Woodpecker Feeding Young
39.4 Adaptive Behavior
• Not all behaviors are adaptive; scientists use experiments to
test hypotheses about the adaptive value of a behavior
• Example:
• Starlings place sprigs of wild carrot in their nests
• Scientists tested the effect of wild carrot sprigs on the
number of blood-sucking mites in nests
• Results: Nests with wild carrots had significantly fewer
mites than those with no greenery
Starling Nest Decorating Behavior