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Chapter 51
• ~Animal Behavior
Behavior-what an animal does and why it
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does it.
Ethology~ study of animal behavior
Behavior results from both genes and
environmental factors.
Causation:
•proximate~ physiological & genetic
mechanisms of behavior
•ultimate~ evolutionary significance of
behavior
Observation of Magnolia
Warbler
• Proximate
• Breeds in spring and
early summer
• Hypothesis-effect of
increased day length on
photoreceptors brings
on breeding.
• Stimulus results in
neural and hormonal
changes that induce
this behavior.
• Ultimate
• Why did natural
selection favor this
behavior?
• Hypothesis-breeding
is most productive
or adaptive at this
time.
• Food more plentiful.
Innate Behavior
• Developmentally fixed
• Often attributed to genetic programming
without environmental influence.
• Baby birds opening mouth for food
• Key point-is the range of environmental
differences among individuals does not
appear to alter the behavior.
Innate Behavior
• Fixed action pattern
(FAP)~ sequence of acts;
unchangeable; carried to
completion
• Sign stimulus ~these
patterns are triggered by an
external sensory stimulus
• Ex: 3-spined stickleback
(Tinbergen ‘73 Nobel)
• Utilizes its color vision to
identify red-undersided
males that try to invade its
territory.
Foraging
• Mechanisms animals use to recognize,
search for, and capture food items.
• Optimal foraging theory
• Feeding costs verses feeding benefits.
Behavioral ecology concentrates
on ultimate hypotheses
• Animals utilize their genetic variation to
express behaviors that optimize their
fitness
• Natural selection favors behaviors that
enhance survival and reproductive
success.
Learning-experience based
modification of behavior
• Maturation~ behavior due to
developing physiological
changes.
• Habituation~ loss of
responsiveness to stimuli
that convey no information;
simple learning
• Imprinting~ limited learning
within a specific time period
•critical period (Lorenz, ‘73
Nobel)
Associative Learning
• Connecting two different stimuli
• Ivan Pavlov-Classical conditioning
• Involves associating arbitrary stimuli
with either a reward or punishment.
• Skinner-Operant Conditioning-trial and
error
• Induced manipulation of levers by rats
after awarding them with food.
Associative Learning
• •classical conditioning~ Pavlov’s dogs
•operant conditioning (trial and error)~
“Skinner’s box”
Social behavior
• Sociobiology~
evolutionary theory
applied to social behavior (Hamilton)
• Agonistic behavior~ contest behavior
determining access to resources
• Dominance hierarchy~
linear
“pecking order”
• Territoriality~ an area an individual
defends excluding others
• Mating systems:
•promiscuous~ no strong pair
bonds
•monogamous~ one
male/one female
• •polygamous~ one with many
•polygyny~ one male/many
females
•polyandry~ one
female/many males
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Agnostic Behavior
• Competition for a
resource
• Sometimes simply ritual
• Signifies intent but
causes no harm
• Causes social
hierarchies to develop
in some animals
• Dominance hierarchy
• Territoriality
Figure 51.19 Ritual wrestling by rattlesnakes
Mating behavior
• Parental investment-time and resources
required to produce an offspring.
• Female usually has higher parental
investment-eggs more costly to produce
• Sexual selection-competition among males
for the female to choice him.
• Females usually care for young. Paternity not
always know. Very few have only male
paternal care.
Altruistic behavior-reducing individual
fitness to increase that of another
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Inclusive fitness~ total effect an
individual has on proliferating its
genes by its own offspring and
aid to close relatives
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Coefficient of relatedness~
measures inclusive fitness by
proportion of genes that are
identical because of common
ancestors
Kin selection~ aiding related
individuals altruistically can
result in more identical genes
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Reciprocal altruism~ exchange
of aid; humans?