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Behavioral Ecology-B2
Chapter 32
I. Nature versus Nurture: Genetic Influences
A. Defined
1. Nature-genetics
2. Nurture-environmental influences
3. Behavior-any action that can be observed
and described.
B. Experiments with Lovebirds, Snakes, and
Snails (nature or nurture)
1. Lovebirds
a. Nest building different among
different species
~Fischer lovebird-carries long
material in their beak
~Peach-faced-carries shorter pieces
in their tail feathers
Hypothesis- If behavior is inherited, then hybrids
might show intermediate behavior.
b. Results-hybrid had difficulty carrying
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nesting material
c. The hybrids showed confusing
behavior with a mix of both that did
not show success with nest building
d. Hypothesis was supported (behavior
has a genetic basis)
2. Garter snakes
a. Test to see if food preference has a
genetic basis
b. Different species will preference for
different organisms.
~feed underwater on frogs/fish
~feed on land eating slugs
c. Hybrids eat both
d. Genetic basis for food preference
~genetics or physiology?
~tongue flicking and smell receptors
are different between species.
e. Nervous and Endocrine systems
coordinate body systems
~are these systems involved with
behavior?
3. Snails
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a. Egg-laying behavior
~long strings of million eggs
~puts it in their mouth, swings it
around to make a solid mass and
then attaches it to a solid object
b. Isolated the hormone that causes the
snail to lay eggs.
c. Hormone causes egg-laying without
a male.
d. Endocrine system can affect behavior
C. Experiments with Humans
1. Twins
a. separated at birth
b. different environmental conditions
2. Results
a. similar food preferences
b. similar activity patterns
c. picked similar looking mates
Hypothesis supported that certain types of behavior
are primarily influenced by nature. (genes)
II. Nature versus Nurture: Environmental Influences
A. Defined
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1. FAP-Fixed action patterns
a. response to a sign stimulus
b. ex. Birds pecking at mother’s beak
2. Learning-a durable change in behavior
brought about by experience.
B. Learning in Birds
1. Introduction
a. pecking behavior of newborn chicks
to get their parent to regurgitate
their food
b. is it FAP or learned?
c. Conclusion (after experimentation)
was that it is both. The behavior
gets better with practice
2. IMPRINTING (simple learning)
a. During the sensitive period (2-3 days
after hatching) the bird imprints on
the first thing it sees
b. interaction between chick and parent
during the sensitive period is key to
normal imprinting
3. SONG LEARNING (different songs and
dialects from different locations)
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a. Do birds learn to sing from their
elders?
TEST-3 groups
1-heard no songs
~Songs not fully developed
2-heard tapes of songs
~Sang songs from tape / same dialect
3-given adult tutor of different species
~Sang song of different species
Learning and social interactions assist birds
C. Associative Learning
1. Defined
a. a change in behavior involving an
association between two events
b. ex. Learn not to eat a substance that
once made you sick. (monarch)
2. Classical Conditioning
a. Defined-Two different types of
stimuli at the same time
makes an association.
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b. Pavlov’s Dog
~bell
~food
~saliva
c. Organism can be trained
(conditioned) to associate any
response to any stimulus
d. ex. Commercials & beautiful people
e. ex. Reading to infants/toddlers
3. Operant Conditioning
a. Defined
~Learning that results from reward
or reinforcing a particular
behavior
b. B.F. Skinner
~mice
~lever
~food
c. Ex. Child rearing/positive feedback
III. Animal Communication
A. Communicative Behavior
1. Communication
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a. Defined-signal by a sender that
influences the behavior of a receiver
b. signals
~purposeful(ex. Bats going into caves)
~no purpose (ex. Moth move away
from Bats radar)
2. Signal types
a. chemical
b. auditory
c. visual
d. tactile
B. Chemical communication
1. Effective 24 hours a day
2. Pheromone-chemical signals in a low
concentration that are passed between
members of the same species.
a. ex. Insects, territorial marking
b. Humans?
~pheromones stimulate hormones
C. Auditory Communication
1. Signals are faster than chemical signals
2. Effective 24 hours a day
3. Can be modified
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~pattern, duration and repetition
4. Ex. Bird Song
a. distress
b. courting
c. territorial
5. Language is the ultimate auditory
communication
a. man (reason)
b. primate-limited
D. Visual communication
1. Used during the day
a. saves energy by using intimidation
b. maintains order in a community
2. Used for courtship-exact signal
~ex. P. 677 figure 32.8 fireflies
3. No need for chemical or auditory signal
~body language and positioning
~human
-hairstyle
-dress
-gait
-Do animals have emotion? P. 679
E. Tactile communication
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1. One animals touches another animal
2. ex. Grooming, calming, young feeding
3. Ex. Bee communication (waggle dance)
IV. Behaviors that affect Fitness
A. Assumptions
1. Behavior is subject to
natural selection (evolution)
2. Behavior has a genetic basis
3. Most behavior must have some adaptive
value
B. Territoriality and Fitness
1. Territoriality
a. occurs mostly during reproductive
times
b. Costs energy to defend
c. Adaptive value?
~ensures a source of food
~exclusive rights to females in area
~area to rear young
~protection from predators
d. varies in size
~energy costs
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2. Foraging for Food
Animals need to ingest food that will provide more
energy than the effort expended acquiring the food.
a. ex. Crabs eat intermediate size clams
because it takes too much energy to
break open the larger clams.
b. More energy = more offspring?
~trade-offs
~intelligence from predators
C. Reproductive Strategies and Fitness
1. Fun facts
a. Primates are polygamous
-males and many females
-females use more energy for
Gestation and nurturing the
Offspring
-males can mate while one is
Gestating
b. A few primates are polyandrous
-one female and many males
-ex. New World monkey
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-males nurture since the offspring
are so large
c. A few primates are monogamous
-pair bonding
-both help with rearing of offspring
-rare in primates (18%)
-occurs when males have limited
mating opportunities, territoriality
exists, and the male is fairly
certain the offspring are his
2. Sexual Selection
a. defined-a form of natural selection
that favors features that increase an
animal’s chances of mating
b. leads to increase fitness
c. Often-female choice and male
competition
~females have eggs and care for
their young so can be choosy
d. females always know the offspring
is theirs…males do not
~males produce lots of sperm
~males increase fitness if they have
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many offspring
~intimidation calls out fitness
-antlers
-lion manes
-auditory, etc.
D. Mating in Humans
A study of human mating behavior shows that the
concepts of female choice and male competition
apply to humans as well as to other animals.
1. Human Males Compete
more men = more competition to mate
a. females invest more in having
a child
~gestation time
~lactation
b. give sperm
c. men more available to mate
d. Dimorphic-males are larger and
more aggressive than females
~more stress (testosterone)
released more often than females
~hormones take a toll on males and
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they usually die sooner than
females (4-7 yrs)
2. Females Choose
Females prefer a mate who can obtain
resources(financial success) and shows symmetry
in facial and body features, related to the “good
genes” hypothesis
(pick so young have better chance to survive)
a. Study out of UT
~financial resources suggested as
number one trait that females
prefer. Very controversial
~increase the fitness (reproductive
success)
b. In the wild-females look at symmetry
to determine the health of genes.
~good genes optimize success of
the survival of offspring
3. Men also have a choice!
a. men prefer youthfulness and
attractiveness in females~provides
good genes for childbearing.
b. Controversial study showed
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~males preferred a waist to hip
ratio of .7 regardless of weight
~physiologically this is the ratio
optimal for conception.
~Men pick women with symmetry,
high estrogen levels (fertility) and
youthfulness
c. smelly t-shirts (science focus p. 684)
E. Societies and Fitness (genes)
1. Hypothesis
~societies form when living in a society
has a greater reproductive benefit
than reproductive cost.
~COST-BENEFIT analysis
2. Group living
a. Benefits
~helps to avoid predators
~helps rear offspring
~helps to find food
~groom each other
b. Disadvantages (costs)
~more competition
~males larger and take more energy
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to rear than females.
Females struggle
~easily spreads disease and
Parasites
c. Humans use health-care and
medicine to offset the cost of living
close to each other.
F. Sociobiology and Human Culture
1. Humans live in societies since the
benefits outweigh the costs.
2. CULTURE
a. total pattern of human behavior
b. cultural evolution surpassed
biological evolution.
3. Why did human societies originate?
a. hunter-gatherers.
~encouraged cooperation,
communication and tools.
b. if predator-prey
~evolution of intelligence?
G. Altruism versus self-interest
1. Altruism defined
~self-sacrificing behavior for the good
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of another member of the society.
-benefits the recipient
2. Altruistic behavior kills the organism
~will this kill the altruistic gene?
-human examples (soldier, firefighter,
mother, saving other individual
regardless of age)
~Animal altruism
a. KIN SELECTION
~saving a close relative saves a
number of the same genes
b. INCLUSIVE FITNESS
~choosing the organism with the
best genes (reproductive success)
3. Reciprocal altruism
a. organisms help to rear offspring
b. benefits may come later in life when
they are rewarded with territory,
food, or the survival of the young
making it to maturity.
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