Transcript The Living World - Chapter 33 - McGraw Hill Higher Education

The Living World
Fourth Edition
GEORGE B. JOHNSON
33
Behavior and the
Environment
PowerPoint® Lectures prepared by Johnny El-Rady
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33.1 Approaches to the
Study of Behavior
Behavior can be defined as the way an organism
responds to stimuli in its environment
The most complex behaviors are exhibited by
animals with nervous systems
Proximate causation – How does it work?
Focus of the field of psychology
Ultimate causation – Why did it evolve?
Focus of the field of ethology (evolutionary behavior)
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33.1 Approaches to the
Study of Behavior
The study of behavior has had a long history of
controversy
Is behavior the result of nature (instinct) or
nurture (learning)?
This is no longer considered an “either-or”
proposition
We now know that instinct and learning
play significant roles
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33.2 Instinctive Behavioral Patterns
Early research in animal behavior focused on
patterns that appeared to be instinctive or innate
These are the same in all individuals of a species
Appear to be based on preset paths in the
nervous system
Ethology is the study of animal behavior in natural
conditions
Its founders were Karl von Frisch, Konrad Lorenz,
and Niko Tinbergen
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Examples of Innate Behavior
Egg retrieval by geese
Behavior is triggered
by a sign stimulus
Egg out of nest
Innate releasing
mechanism provides
the neural instructions
that detect stimulus
Fig. 33.2a
A fixed action pattern is triggered
Intricate egg retrieval behavior
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Sign stimuli are often not very specific
Male stickleback fish develop red coloration on their
undersides during breeding season
React aggressively to approach of other males
Red color is the sign
stimulus
Fish displayed
aggressive
postures when
challenged with
unfishlike models
with red strips!
Fig. 33.2b
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33.3 Gene Effects on Behavior
Behavioral genetics is the study of how genes
influence behavior
Many behaviors are inherited in Mendelian fashion
Crosses of two species showing different behaviors yields
hybrids with “intermediate” behavior
A study of human twins revealed the following
Identical twins separated at birth and raised apart
developed many similarities in personality
Fraternal twins raised together had personalities no more
similar than those raised apart
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33.3 Gene Effects on Behavior
Normal mother
In 1996, the fosB gene
was discovered in
mice
It seems to
determine whether
female mice will
nurture their young
Fig. 33.3
Mother with two mutant fosB alleles
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33.4 How Animals Learn
Learning is the modification of animal behavior as a
result of previous experiences
Non-associative learning
No requirement for an association between two
stimuli or between a stimulus and a response
Sensitization
Repeating a stimulus produces greater response
Habituation
Decrease in response to a repeated stimulus
Learning not to respond to a particular stimulus
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Associative learning
Involves formation of an association between two
stimuli or between a stimulus and a response
The behavior is conditioned
Classical conditioning
Paired presentation of two stimuli causes an
animal to create an association between them
Pavlovian conditioning
Operant conditioning
An animal learns to associate its behavioral
response with a reward or punishment
Trial-and-error learning
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Imprinting
Social attachments to other individuals that will
profoundly influence behavior later in life
Filial imprinting occurs
between parents and
offspring
Birds will follow the first
object they see after
hatching
They direct their
social behavior
toward that object
as their mother
Konrad
Lorenz
Fig. 33.4
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33.5 Instinct and Learning Interact
to Determine Behavior
Some animals have innate predisposition toward
forming certain associations
Pigeons learn to associate food with colors but not sounds
However, they associate danger with sounds not colors
This learning preparedness demonstrates that learning is
possible only within the boundaries set by instinct (genes)
Knowledge of an animal’s ecology is key to
understanding what an animal is capable of learning
Clark’s nutcracker have an extraordinary spatial memory
These birds have a large hippocampus
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Courtship songs sung by mature birds are species-specific
White-crowned sparrows that heard no song at all during
rearing, had a poorly developed song as adults
The same was true
if they heard only
the song of a
different species,
the song sparrow
However, birds that
heard the song of their
own species, sang a
fully-developed “whitecrowned” song as
adults
Fig. 33.5
Thus, song development involves
both instinct and learning
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33.6 Animal Cognition
A central question in animal behavior is whether nonhuman animals show cognitive behavior
Do they process information and respond in a manner that
suggests thinking?
Some examples provide evidence of conscious
planning
Japanese macaques can separate grain from sand
Chimpanzees use twigs to probe entrance to termite nest
Sea otters bash clams against rocks to break them open
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There is also compelling evidence that animals can
solve problems
Chimpanzees could not get to bananas by jumping
They ultimately got to it by placing boxes on top of
each other and climbing on them!
Ravens figured out how to
get to meat at the end of a
string
They pulled up a bit of
string and stepped on it
This process was
repeated until the food
was within reach!
Fig. 33.6
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33.7 Behavioral Ecology
The study of animal behavior can be divided into
1) A study of its development
2) A study of its physiological basis
3) A study of its function
Behavioral ecology is the study of how natural
selection affects behavior
Focuses on the adaptive significance of behavior
How behavior may increase survival and
reproductive success, or fitness
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33.7 Behavioral Ecology
Adaptive traits confer evolutionary advantages in
different ways
Some behaviors reduce predation
Egg-shell removal by gulls reduce predation by crows
Other behaviors enhance energy intake
This allows more offspring to be supported
Other behaviors increase resistance to disease
Still others enhance the ability to acquire a mate
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33.8 A Cost-Benefit Analysis
of Behavior
Every behavior that offers a survival advantage for
an individual comes with an associated cost
Foraging behavior allows an animal to choose what
food to select, and how far to go seeking it
Optimal foraging theory
Animals select foods that maximize their net
energy intake per unit of foraging time
However, avoiding predators is an important
consideration
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Territoriality is behavior in which individual members
of a species maintain exclusive use of an area
Territories are defended
by displays and overt
aggression
Sunbirds increase
nectar availability by
defending flowers
However, a defensive
cost is increased
predation
Fig. 33.8
Thus, for a behavior to be favored by natural selection, the
benefits have to outweigh the costs
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33.9 Migratory Behavior
Many animals breed in one part of the world, and
spend the rest of the year in another
Long-range two-way annual movements like this
are called migrations
Migratory behavior is particularly common
among birds
Ducks and geese
Warblers
Starlings
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33.9 Migratory Behavior
Compass sense – An innate ability to move in a
particular direction (called follow a bearing)
Map sense – A learned ability to adjust a bearing
depending on the animal’s location
Experiments on starlings indicate that inexperienced
birds migrate with an innate compass sense
On the other hand, older experienced birds use a
learned map sense to aid their navigation
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Fig. 33.9 Starlings learn how to navigate
Transport of
captured birds
Flight of
experienced birds
Flight of
inexperienced birds
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33.9 Migratory Behavior
How is the compass sense achieved?
Migrating birds detect the earth’s magnetic field
and orient themselves with respect to it
Sun and stars may also be used for orientation
How is the map sense achieved?
Recognition of certain cues, like the position of
mountains and coastlines
Migration through featureless terrain presents
more of a puzzle
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33.10 Reproductive Behaviors
Reproductive behaviors encompass a variety of
animal behaviors, including courtship
Competition for mating opportunities has been
termed sexual selection
Intrasexual selection
Competition between members of one sex
(usually males)
Intersexual selection
Essentially, mate choice
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Intrasexual selection leads to evolution of structures
used in combat with other males
Deer’s antlers or ram’s horns
Intersexual selection leads to evolution of complex
courtship behaviors and “ornamental” structures
Female peahens
prefer to mate with
males with greater
number of eyespots
in their tail feathers
Fig. 33.10
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The benefits of mate choice for the female
1. The male that provides the best offspring care
2. The male that provides the best territory
3. The male that provides the best genes
The typical number of mates an animal has during
its breeding season is called the mating system
Monogamy – One male and one female
Polygyny – One male and many females
Polyandry – One female and many males
Polygyny is more common than polyandry
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An animal’s reproductive strategy involves
“decisions” regarding the following
The choice of mates
The number of mates
The time and energy to devote to rearing
offspring (parenting)
The two sexes of a species often have different
reproductive strategies
In most animal species, females exercise more
mate choice and parental investment
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33.11 Communication Within
Social Groups
Many insects, fish, birds and mammals live in social
groups
Communicated information includes
Alarm calls indicate
predators
Alarm pheromones
trigger attack behavior
Trail pheromones
organize cooperative
foraging
Fire ants
Fig. 33.11
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European honeybees use a very complex dance
language to direct hivemates to rich nectar sources
A scout returning from a foraging trip performs a
waggle dance that resembles a figure eight
The direction of the food
source relative to the
direction of the sun is
indicated by the angle of
the straight run
The distance to the food
source is indicated by the
tempo, or degree of vigor,
of the dance
Fig. 33.12
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Primate language
Some primates have a “vocabulary” that allows
individuals to communicate the predator identity
The vocalizations of African vervet monkeys
distinguish between leopards and eagles
Each distinctive
call elicits a
different and
adaptive escape
behavior
Fig. 33.13
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All of the roughly 3,000 human languages draw from
the same set of 40 consonant sounds
Language develops at an early age in humans
Individuals who have not heard certain consonant sounds
as infants can only rarely produce them as adults
Language acquisition goes through several stages
“Babbling”
Vocabulary of thousands of words
Simple sentences that convey information
Learning the rules of grammar
Nonverbal communication includes “body language”
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33.12 Altruism and Group Living
Altruism is the performance of
an action that benefits another
individual at a cost to the actor
Helpers at the nest in some bird
species
Sentinels that give predator-alarm
calls in some mammalian species
Fig. 33.14
Meerkat
The existence of altruism among animals is rather
perplexing
Natural selection should operate against it
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Altruistic behavior may not be truly altruistic after all
The actor may benefit
Nest helpers may get parenting experience or inherit
territory
Sentinels may be able to escape predators in the
confusion following the alarm call
Individuals may benefit directly if there is a mutual
exchange of altruistic acts
In reciprocal altruism, “cheaters”
(nonreciprocators) are discriminated against
These individuals are cut off from receiving
future aid
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An altruist compensates for the reduction in its own
reproductive success by increasing that of relatives
Selection that favors altruism directed toward relatives is
called kin selection
The more closely related two individuals are, the greater
the potential genetic payoff
White-fronted beeeaters
Helpers tend to be
close relatives
Helpers’ assistance
increases with
genetic relatedness
Fig. 33.15
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33.13 Vertebrate Societies
Vertebrate social groups are usually less rigidly
organized and cohesive than insect societies
Some vertebrate complex social systems exhibit
both reciprocal and kin-selected altruism
However, vertebrate societies tend to display more
conflict among members than insect societies
Conflict (and aggression) center on access to
food and mates
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The organization of vertebrate societies is influenced
by ecological factors such as food and predation
African weaver birds
Savanna-dwelling species build colonial nests
Have a polygynous
mating system
Forest-dwelling
species build solitary
nests
Monogamous pairs
form and cooperate
to find limited food
resources
Fig. 33.16
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Naked mole rats are rare among vertebrates in that
they form large organized societies
These underground
colonies have a true
division of labor
A single female
or “queen” does
all the breeding
Fig. 33.17
Workers, consisting of both sexes, keep the tunnels
clear and forage for food
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33.14 Human Social Behavior
Sociobiology is the study of the evolution of social
behavior in animals
Pioneered by Edward O. Wilson, this field has
proven highly controversial
No animal exhibits cultural differences to the degree
seen in human populations
Both genetics and learning play key roles in
complex human social behavior
However, the extent of each is hotly-debated
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