Transcript Chapter 51 PPT notes

BEHAVIOR
• Is what an organism does, and why it does
that (usually associated with animals)
• Is assumed to increase fitness (ultimate
causation)
• Occurs in response to some stimulus
(proximate causation)
Example 1: Bluegill behavior
• Bluegills breed in spring or early summer
• Ultimate causation: breeding is most
successful when temperatures and food
supplies are optimal
• Proximate: Breeding is triggered by the
effect of the increased day length on the
pineal gland
Example 2: Human sweet tooth
• Ultimate causation: sweet, high-energy
foods were rare prior to mechanized
agriculture
• Proximate: sweet taste buds increase the
chance of eating high energy foods
NATURE VS. NURTURE
• THAT old argument! It’s finally been
agreed that both contribute to behaviors
• The degree of each is still questioned by
some, but the “smart scientist” (tee-hee)
gives each about 50%
• Behaviors display a range of phenotypes
which the genotypes expressed
(continued)
• Environmental factors affecting behavior:
the chemical environment of the cell,
hormonal and physical conditions, and
interactions with other organisms, to name a
few
INNATE BEHAVIOR
• Is present at birth but needs an environment
in which to be expressed
• Is considered fixed if they are not
influenced by environment or individual
differences
• Ethology (1930s): study of animals in their
environment (before behavior bio existed)
(continued)
• Was an attempt to understand now a
variety of animals behaved in their
natural habitats
Hosie’s question: What would be the
single most difficult part of getting reliable
observations in such a study?
(continued)
• Developed the concept of a fixed action
pattern—a sequence of behaviors that are
essentially unchangeable and usually
carried to completion once initiated
• A FAP is triggered by an external sensory
stimulus called a sign stimulus
– In many cases, the sign stimulus is some feature
of another species
Examples:
• Some moths fold their wings and drop to
the ground the (FAP) in response to the
ultrasonic signal put out by bats (the sign
stimulus)
• In the male three-spined stickleback fish,
the males will attack (the FAP) other males
that invade his territory if it has a red belly
(the sign stimulus is the red belly)
BEHAVIORAL ECOLOGY
• Emphasizes evolutionary hypotheses, which
is emphasized by the study of behavior in
an ecological context
• Because natural selection works on genetic
variation (tons of it in nature!), we expect
organisms to possess features that maximize
their genetic representation in the next
generation (recombination, mutation aside)
(continued)
• In plain English, we expect animals to
behave in ways that maximize their fitness in
the environment
– Sexual selection tends to maximize healthy
offspring
– Feeding behavior is likely to optimize net energy
gain
– This is pretty much the definition of behavioral
ecology
COST/BENEFIT ANALYSIS
OF FORAGING BEHAVIOR
• Obviously, feeding is essential to survival and
reproductive success
• Foraging (feeding behavior) is a favorite item of
study at both the proximate and ultimate levels
among behavioral biologists
• Foraging behaviors directly linked to morphology
• BE’s use cost/benefit analysis to study proximate
and ultimate causes of diverse foraging strategies
(continued)
• Generalists feed on a wide variety of items
(sea gulls, bears)
– Most do not choose food randomly, though it
may concentrate on a specific item if it is in
abundance
– Requires the organism to develop a search
image (set of key characteristics that will lead it
to the desired object)
(continued)
• Specialists feed on one specific source, and
may starve even if other similar items are
presented
– Their morphology and behavior is highly
specific to their one source of energy
(continued…again)
• Search images enable an animal to combine
efficient short-term specialization but with
the flexibility of generalization
• Optimal foraging favors animals choosing
foraging strategies that maximize benefit
and minimize cost (time and energy spent
foraging ISN’T being spent doing other
things)
LEARNING
--Is experienced-based behavior
modification
--are various forms
--can affect innate behaviors
(efficiency)
HABITUATION
• Loss of responsiveness to stimuli that conveys
little or no information
• Why crows wait until the last minute before
leaving their flattened fauna behind…
MATURATION
1. CHANGES IN INNATE
BEHAVIORS NOT ALWAYS DUE TO
LEARNING
2. MATURATION: ONGOING
DEVELOPMENTAL CHANGES (I.E.,
BIRDS LEARNING FLIGHT)
ARE YOU MY MOTHER?
• Limited to a specific time
in life
• Lorenz mothered graylag
geese raised in the lab
• They did not know their
own mother!
• Adults need to imprint on
children as well
• Critical period is when
imprinting occurs
ASSOCIATIVE LEARNING
• CLASSICAL CONDITIONING WAS
MADE FAMOUS BY PAVLOV
(STIMULUS VS. REWARD OR
PUNISHMENT)
• OPERANT CONDITION IS TRIALAND-ERROR LEARNING (HOW MANY
TIMES WILL YOU KISS A
PORCUPINE?)
PLAY
• HAS NO APPARENT EXTERNAL GOAL
• MOVEMENTS CLOSELY ASSOCIATED
WITH GOAL-DIRECTED BEHAVIORS
• “PRACTICE HYPOTHESIS”
• CHILDREN “HORSING AROUND”
RESULTS IN SAME TYPE INJURIES
SEEN IN OTHER SPECIES
ANIMAL COGNITION
• IS THE ABILITY OF THE NERVOUS
SYSTEM TO PERCEIVE, STORE,
PROCESS, AND USE INFORMATION
GATHERED BY THE SENSORY
RECEPTORS
• STUDIED BY COGNITIVE
ETHOLOGISTS (STUDY OF
AWARENESS, CONSCIOUSNESS)
COGNITIVE MAPS
• SOME ANIMALS FORMULATE
INTERNAL REPRESENTATIONS
(SPATIAL RELATIONSHIPS)
• ANIMALS HAVE AN “IMAGE” OF
THEIR OF THEIR FORAGING AREAS
• TAXIS AND KINESIS MAY OCCUR
WITHOUT INTERNAL
REPRESENTATION
KINESIS
MOVEMENT WHICH INVOLVES A
SIMPLE CHANGE IN ACTIVITY
RATE IN RESPONSE TO A
STIMULUS (SOWBUGS,
WOODLICE)
DON’T MOVE TOWARD/AWAY, JUST
STAY BECAUSE THEY SLOW DOWN
THERE
TAXIS
MORE OR LESS AUTOMATIC
MOVEMENT, TOWARD A
POSITIVE OR AWAY FROM A
NEGATIVE STIMULUS
MIGRATION BEHAVIORS
--REGULAR
MOVEMENT
OVER
RELATIVELY
LONG DISTANCES
MIGRATION (CONT.)
• ORIENTATION:
ANIMAL DETECTS
COMPASS POINTS,
TRAVELS IN
STRAIGHT LINE
• NAVIGATION:
PRESENT
LOCATION
RELATIVE TO
ELSEWHERE
Social Behavior & Sociobiology
• Sociobiology places social behavior in an
evolutionary context
– Social behavior: broadly defined as any kind of
interaction between 2 or more animals, usually the
same species
– Aggression, courtship, cooperation and deception
are part of the behavioral landscape of social
behavior
– Has both costs and benefits to members of species
that interact
SOCIOBIOLOGY
• Relatively new discipline which applies
evolution as a foundation for interpretation
of behavior
• Members of the same niche (among a
population) have strong potential for
conflict
– This is especially true for species who maintain
pops. near the carrying capacity
• Behavior is considered cooperative when
more individuals perform work more
efficiently than an individual
• Most animals will still act in a way for
maximum benefit of self (even at cost to
other participant)
COMPETITIVE SOCIAL BEHAVIORS
OFTEN REPRESENT CONTESTS FOR
RESOURCES
Agonistic behavior: involves both
threatening & submissive
behaviors;determines the “winner”
Threat is often exaggerated, but no always
Includes much “ritual” (symbolic activity)
DOMINANCE HEIRARCHIES occur in
groups maintained by agonistic behavior
Chickens are a prime example—pecking
order (unfamiliar chickens respond w/ pecks)
An alpha is the highest ranked animal,
omega the least
Wolves are another example-only alphas
Territoriality
Territory=an area an individual defends
(usually excludes members of own species)
Used for feeding, mating, rearing young, or
combinations of these
Is usually a fixed location, but size varies
by species
Home range is not territory, and is
usually not defended
Are established and defended through
agonistic behavior
Natural selection does not always favor
territoriality; it takes energy to defend one’s
territory
Is usually directed at conspecifics (mating,
resources)
“fair shares” often result in population
crashes
Mating behavior relates directly
to fitness
• Courtship
– Most animals are not conscious of reproduction
– Mating interactions are very complex in the
animal kingdom
• Courtship allows animals to chose mates
from potential candidates
– Females more discriminating than males
– Females have greater parental investment
(continued)
• Eggs more costly to produce than sperm
• Females expend more energy producing offspring
• Sexual selection is a mechanism of natural selection
– Assessment helps animals select a mating
partner
• Based on ability of mate to help rear or provide for
offspring, usually
• May be based on genetic quality
– Birds, some insects display in “leks” where females visit
to choose a mate most fit
o Basis for assessment is
difficult to determine
o sometimes may simply
be male-male competition
o sometimes certain
males may display best
qualities (secondary sex
characteristics,
showiness, etc)
Ritualized behavior
• may have evolved
from something
more direct
• male dance flies
carry silk balloons
carrying food
•Copulation occurs
after female accepts
balloon
Interactions depend on
communication
• Displays (songs, dances,
etc.)
• Pheremones (chemical
[olfactory] signals)
• Honeybee “waggle”
dance (which some
scientists question
evidence of the pattern)
ALTRUISTIC BEHAVIOR
• Altruism: decreases individual fitness but
increases fitness of recipient
– “unselfish” behavior
– Ex: Belding ground squirrels warn of
predators, allowing others to escape, but
identifying its own position; worker bees kill
intruders to defend the queen, which results in
their deaths
Inclusive Fitness
• The total effect an
individual has on
proliferating its genes
by reproducing and by
aiding other close
relatives
• Coefficient of
relatedness quantifies
inclusive fitness
• Is a proportion of
genes that are identical
in 2 individuals due to
common ancestors
• COR is 0.5 in siblings
(50% match); 0.125
for cousins
• Higher COR is more
likely to receive aid
(kin selection)
Reciprocal Altruism
• Rare in all animals but humans
• Some say altruism only occurs in humans
• Debate rages about influence of biological
evolution vs. culture in humans
• Avoidance of incest is the specific context
of this debate
– Is adaptive, as inbreeding increases defective
allele frequencies
• humans as wells as many bird and mammal
species avoid incest
• Is the aversion innate?
• Is it acquired by socialization?
• Can culture escape biology?
“Behavioral characteristics are expressions of
genes favored by natural selection.”
--sparked the debate about the connection
between biological evolution and culture
CULTURAL TABOOS ON
INCEST
• Incest avoidance is adaptive because
“inbreeding” may increase the frequency of
genetic disorders
• Many species avoid it, and most human
cultures forbid it
• So: is this an innate aversion or an acquired
behavior
(continued)
• “Nurture” (learned) says that cultural taboo
is unnecessary if the behavior is innate
• “Nature” (genetic) says that taboos are
proximate mechanisms reinforcing
avoidance behaviors that ultimately evolved
because of its effect on fitness
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