ANIMAL BEHAVIOR
Paige, Emily, and Lily :)
-ethology- the scientific study of how
51.1 animals behave, particularly in their
natural environments
-Understanding Behavior requires
answering four questions, two about
proximate causation, asking how a
behavior occurs or is modified, and two
about ultimate causation, why a behavior
occurs in the context of natural selection.
1. What stimulus elicits the behavior, and
what physiological mechanisms mediate the
response?
2. How does the animal’s experience during
growth and development influence the
response?
3. How does the behavior aid survival and
reproduction?
4. What is the behavior’s evolutionary history?
Proximate Causation Example: How do
seasonal changes influence when red-crowned
cranes mate?
Ultimate Causation Example: Why do redcrowned cranes reproduce in spring and
summer?
Fixed Action Patterns
-fixed action pattern- a
sequence of unlearned
acts that is essentially
unchangeable and, once
initiated, usually carried
to completion.
One example of a fixed action pattern is
prominent in male stickleback fish. The male
sticklebacks have red bellies and they attack
any other males that invade their territory.
Scientists observed that male sticklebacks
acted aggressively when a red truck was
passing a tank of them. As it turns out, the
males will not attack fish lacking red
coloration, but they will attack anything, even
unrealistic models, if they contain any red at
all.
The trigger of this aggression is known as a sign stimulus.
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Kinesis and Taxis:
-Kinesis is a change in activity or turning rate in response
to a stimulus
An example of kinesis is when sow bugs become more
active in dry areas and less active in humid areas. Note:
they do not move toward or away from a specific
condition. They are more likely to leave a dry area and
encounter a moist one.
Taxis
-Taxis is an oriented movement toward or
away from some stimulus.
An example of taxis is when trout
automatically swim or orient themselves in an
upstream direction (toward the current).
-MIGRATION- a regular, long-distance change in location
How do animals find their way?
-Some animals track their position relative to the sun
-Problems with this approach come about when clouds cover up the sun (and the north
star for nocturnal animals)
-However, evidence suggests that some animals have circadian clocks, internal
mechanisms that maintain a 24-hour activity rhythm or cycle.
-There are two competing hypotheses for another way that animals find their
direction:
-Earth’s pull on magnetite-containing structures triggers transmission of nerve
impulses to the brain. (pigeon study-by sensing their position relative to the Earth’s
magnetic field, pigeons and other animals can navigate without solar or celestial
bodies)
-Animals are guided by the effects of Earth’s magnetic field on photoreceptors in the
visual system. (birds require light of particular wavelengths in their daytime or
nighttime environments to orient themselves)
Animal Signals/Communication
-A stimulus transmitted from one animal to another is called a SIGNAL.
-Example- a male fiddler crab generates a stimulus in female crabs by waving
his claws.
- Four types of communication (in a stimulus-response chain) are necessary
for fruit flies to mate.
1. Visual communication
2. Chemical communication
3. Tactile communication
4. Auditory communication
51.1 Questions
1. Give an example of Kinesis.
2. What is one hypothesis of how animals find
their way when migrating?
3. Name two of the four types of
communication necessary for fruit flies to
mate.
51.2 Learning establishes specific links between
experience and behavior
● Innate behavior- developmentally fixed this way, ex.
smiling, walking, nursing
● Tinbergen’s second question “How does the animal’s
experience during growth and development influence the
response?”
● An approach to answer this question is a cross-fostering
study.
● Babies from one species are placed in the care of another,
the amount of change in the babies’ behavior helps
measure how much environment influences behavior.
● Example- mice, one species is aggressive the other less so
Learning: modification of behavior based on specific
experiences
● Imprinting- includes both innate and learned behavior,
formation at a specific stage in life of a long-lasting
behavioral response to a particular individual or object.
● Diff. from other types of learning- has a sensitive period
● In this period, the babies imprint and learn basic
behaviors of their species and the parent learns to
recognize their babies
● If the bonding doesn’t occur the parent will not care for
the baby
Who is my mommy? How do babies know what to
imprint on?
● Experiments of different types of
waterfowl show that they don’t
innately recognize a “mother”. They
identify with the first thing
encountered with key characteristics.
ex. the imprinting stimulus for greylag
geese is a nearby object moving away.
● These goslings imprinted on Konrad
Lorenz. They showed no recognition of
the biological mother.
Spatial Learning and Cognitive Maps
● Every natural environment is different- nest locations,
food, hazards, mates etc.
● An organism's fitness is enhanced by it’s ability for spatial
learning.
● the memory that reflects the environment's spatial
structure. ex. digger wasps, knew which burrow was theirs
by landmarks
● A sophisticated form of spatial learning is cognitive
mapping
● A representation in the nervous system of the spatial
relationships of objects in a animals surroundings. ex.
Clark’s nutcracker bird- seeds hidden halfway between
Associative Learning
● Bluejay eats a monarch butterfly, because of
milkweed the bird vomits soon after. Bluejay learns
not to eat monarch butterflies.
● This is called associative learning- ability to associate
one environmental feature with another.
● Laboratory studies use it, involves classical and
operant conditioning.
● Classical- ring bell before feeding, salivates when bell
is rung
● Operant- trial and error, animal learns to associate a
behavior with a reward or punishment, and avoids or
repeats it.
Cognition and Problem Solving
● Most complex forms of learning involve cognition
● The process if knowing that involves awareness, reasoning,
recollection, and judgement.
● Many groups of animals, like insects, show cognition in
controlled studies.
ex. Bees, rewarded for
choosing same as stimulus,
when pattern changed, still
chose same as stimulus, same
for different.
Cognition and Problem Solving cont.
● Problem solving- the cognitive ability of devising a
method to proceed from one state to another in the
face of real or apparent obstacles.
● ex. chimpanzee is in a room with boxes on the floor
and a banana hung out of reach. Chimp will stack
boxes to reach food. Is highly developed in some
mammals, and also varies with individual experience
and abilities.
Social Learning
● Many animals learn to solve problems by watching
other individuals.
● This is called social learning, ex. Mr. Wahl and math
problems, chimps learning how to crack open pine nuts
● Social learning forms the roots of culture.
● Defined as a system of information transfer through
social learning or teaching that influences the behavior
of individuals in a population.
● Cultural transfer can alter behavioral phenotypes and
influence the fitness of an individual.
51.2 Questions
1. What’s an example of a cross-fostering study?
2. What are two ways associative learning is used in
laboratory studies?
3. How does social learning changes human behavior?
51.3 Selection for individual survival and reproductive
success can explain most behaviors
Natural selection refines behaviors that enhance feeding efficiency.
● Optimal foraging model-maximize benefits minimize energy expended
and danger
● example: northwestern crow cracking whelk(sea snails)
they drop the whelk until its shell breaks, higher expends
more energy but better chance of a break. Results: there is
an optimal drop height, 5 m, the lowest height that still
breaks the shell.
● Predators: Some easy, close food will not be taken advantage of because
of predators in the area-cost benefit
Mating Systems and Sexual Dimorphism
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Promiscuous mating-no strong pair-bonds
monogamous-mates remain together for a long time (1 male, 1 female)
polygyny-single male mates with many females
polyandry-single female mates with many males
● Sexual dimorphism-the extent males and females differ in appearance,
often depends on their mating system.
1. monogamous-very alike,ex seagulls
2. polygynous-dimorphic, males are showier and larger, ex elk
3. polyandrous-dimorphic, females are showier, ex Wilson’s phalaropes(bird
Mating Systems and Parental Care
Why do certain animals use certain mating systems?
● Monogamous- the young need both parents to care for them so there is a
greater benefit for the male and female to stay together than to
separate. ex: most birds
● polygyny- the young do not need the parents to care for them so it is a
greater benefit for the males to seek other mates.
● certainty of paternity- young born to a female have to contain her genes
but a different male could be the father. It explains why exclusively
male parental care in birds is rare. Their mating uses internal
fertilization.
● External fertilization-ex fish- COP is higher so males often take full
parental care.
Sexual Selection and Mate Choice
Mate Choice by Females
1. The female’s mate preferences help determine the evolution of male
behavior and anatomy. ex: selecting based on a showy feature- the males
over time will be showier
2. imprinting influence-females take cues from their fathers for choosing
mates. ex: if father has is ornamented, daughter will prefer an
ornamented mate. If father is not ornamented, daughter will not have a
preference.
3. Mate-choice copying-an individual in a pop. copies the mate choice of
others. ex: female guppy with no other females present will pick a showy
orange guppy. A female guppy with model female guppies present that
pick the less showy will also pick the less showy.
4. Why mate choice copying? If other females prefer a certain male that
female also wants to mate with him because that means his offspring will
be desirable to the population
Male Competition for Mates
Males also can diminish male variation.
● Agonistic behavior: a contest between males often based on strength and
size to determine who gains food, mates, and resources.
Game Theory
● evaluates alternative strategies in situations where the outcome depends
on the strategies of the individuals involved.
Ex: side blotched lizards-males can have an orange throat,blue throat, or
yellow throat. Each color means a different thing. Orange- aggressive. Blueless aggressive. Yellow-sneaky. The success of each depends on the amount
of that trait in the population(frequency dependent selection). (similar to
rock paper scissors)
51.3 Questions
1. Why are certain animals monogamous?
(hint: think of their young)
2. Why do females sometimes copy the mating
preferences of other females in their
population?
3. Give an example of a species that uses
game theory to compete for mates.
51.4- Selection for individual survival and reproductive success can
explain most behaviors
Foraging-food-obtaining behavior
There are observable and interpretable
evolutionary changes in behaviors in
laboratory populations of fruit fly larvae when
foraging for food.Fruit flies that were grown in
a dense population tended to travel further
than those grown in a less dense area.
Optimal Foraging Model: says that natural selection should favor a foraging
behavior that minimizes the costs of foraging and maximizes the benefits
Example: Northwestern crows must drop their food from a certain height in
order to break the shells. Cost vs. benefits: while flying higher may break the
shells faster, more energy is used. Crows have evolved to drop food from the
height that minimizes energy loss but also minimizes time spent trying to
break the shells.
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Mating Systems/Parental Care:
-Promiscuous- a mating relationship no strong pair-bonds or lasting
relationships
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-Monogamous- mates remain together for a longer period of time
-Polygamous- an individual of one sex mating with several of the other (often
a single male and many females-called polygyny, although some species
exhibit the opposite, polyandry)
-If the offspring require a large, continuous food supply and attention, a male
that stays with and helps a single mate may ultimately have more viable
offspring than it would by going off and seeking other mates-this may explain
why most birds are monogamous. However, if the offspring can get along
okay without their parents, the male dreives less benefit from staying with
their partner.
Sexual Selection and Mate Choice
-A female that chooses a healthy male is likely to produce more offspring to
survive and reproduce (male stalk-eyed flies)
- Imprinting can also contribute to mate choice
- Agonistic behavior- an often ritualized contest that determines which male
competitor gains access to a resource, such as food or mates.
-The outcome of such contests may be determined by strength, size, or the
effective use of horns, teeth and so forth.
51.4 Questions
1. What is polygyny?
2. What is an example of the optimal foraging
model?
3. What factors determine whether a male
would do better to stay with one mate or to
mate with several females?