Post on 04-Sep-2020
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Animal Behavior
What is Behavior? Behavior
• everything an animal does & how it does it
• response to stimuli in its environment
Why Study Behavior?
Evolutionary perspective…
• part of phenotype
• acted upon by natural selection
• lead to greater fitness?
• lead to greater survival?
• lead to greater reproductive success?
Understanding Behavior
Causes of Behavior
Proximate cause:
“how” a behavior occurs or is modified based on its immediate interactions with the environment
Ultimate cause:
“why” a behavior occurs in context of natural selection
- how does behavior contribute to survival and reproduction
Male songbird what triggers singing? how does he sing? why does he sing?
Courtship behaviors in cranes how does day length influence breeding? why do cranes breed in spring?
BEHAVIOR: A male stickleback fish attacks other male
sticklebacks that invade its nesting territory.
PROXIMATE CAUSE: The red belly of the intruding male acts as
a sign stimulus that releases aggression in a male stickleback.
ULTIMATE CAUSE: By chasing away other male sticklebacks,
a male decreases the chance that eggs laid in his nesting
territory will be fertilized by another male.
Types of Behavior
Is it nature or nurture?
•Innate behavior: behavior performed correctly and in the same way by all individuals of a species, without previous experience (genetic cause)
- “built in”, not learned,
•Fixed Action Pattern (FAP): innate behavior that occurs as an unchangeable sequence of actions
- triggered by sign stimulus
- conducted to completion once started - ensures that activities essential to survival are performed correctly and without practice
The graylag goose responds to an egg outside her nest with a set of specific actions. Even when the egg is removed, the goose will continue to push at the air with her beak until she completes the FAP
Types of Behavior
Innate Behavior
Fixed Action Pattern
Sign Stimuli-
Attack on red belly stimulus
Court on swollen belly stimulus
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Types of Behavior Innate: Directed movements
Taxis
- change in direction
- automatic movement toward (positive taxis) or away from
(negative taxis) a stimulus
- phototaxis
-chemotaxis
Kinesis
- change in rate of movement in
response to a stimulus
Positive rheotaxis keeps trout facing into the current, the direction from which most food comes. Kinesis increases the chance that a sow bugs will encounter and stay in a moist environment.
Types of Behavior
Innate: Migration
•Regular, long-distance change in location
•Environmental cues: sun, stars, earth’s magnetic field, landmarks
monarchs
Circadian rhythm:
•Internal biological clock
• follows an approximately 24- hour natural cycle
The Suprachiasmatic nuclei (SCN) region is located in the hypothalamus of the brain. The SCN sends signals throughout the body in response to dark and light.
The circadian clock in the hamster brain signals a change in coat color according to season by releasing the hormone melatonin.
Plants can have two internal clocks: one sensitive to light and the other sensitive to temperature
Signal: stimulus that causes a change in behavior;
basis of animal communication
Pheromones – chemicals emitted by members of one species that affect other members of the species (eg. Queen bee, fruit fly, fish, termites, trees, humans)
• Visual signals – Warning flash of white of a mockingbird's wing
• Tactile (touch) – Male fruit fly taps female fly
• Auditory signals – screech of blue jay or song of warbler
Honeybee dance language
•bee returning from the field performs a dance to communicate information about the distance and direction of a food source
Minnows after alarm
Minnows before alarm
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Types of Behavior
Learned behaviors
• modified by experience
• variable, changeable
• flexible with a complex & changing environment
Interaction of Genes
and Experience
How does inheritance and experience form a particular behavior?
Biologists mated two different
species to form a hybrid species
Conclusion: hybrid offspring could alter inherited behavior based on experience.
Types of Learning
Learning: a change in an animal's behavior resulting from specific experiences
Types of learning:
1. Habituation: type of learning in which an animal stops responding to a repeated stimulus that conveys little or no important information
ex: ticking of a clock
2. Imprinting: learning that is limited to a specific time period in an animal's life and that is usually irreversible
learning + innate components
critical learning period : time period in which imprinting takes place
Lorenz: Greylag goose experiment
Control: mother rears young in nest
Experimental: Lorenz rears young in incubator
Result:
Control group: normal imprinting, followed mother, had normal goose relationships
Experimental group: imprinted on Lorenz, followed him, preferred human relationships to geese
BEHAVIOR: Young geese follow and imprint on their mother.
PROXIMATE CAUSE: During an early, critical developmental stage, the
young geese observe their mother moving away from them and calling.
ULTIMATE CAUSE: On average, geese that follow and imprint on their
mother receive more care and learn necessary skills, and thus have a
greater chance of surviving than those that do not follow their mother.
Types of Learning
3. Spatial Learning
• Cognitive Map: internal representation of spatial relationship among objects in an animal’s surroundings
Birds use spatial maps to relocate nut caches
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Some organisms move in response to a recognized object or environmental cue, a landmark.
t
No nest
Nest
4. Associative learning: learning to associate a stimulus with a consequence
•Classical conditioning - learning that a particular stimulus or a particular response is linked to a reward or punishment
- rat will push a level if it receives
food for pushing the level - predator avoids specific prey
associated with a painful experience
•Operant conditioning - trial & error learning - associate behavior with reward or punishment ex: learning what to eat
Pavlov’s dogs
Insight: the ability to respond appropriately to a new situation without previous experience
5. Cognition: process of knowing that involves awareness, reasoning, recollection, judgment
• Problem-solving behavior relies on cognition
6. Social learning: learning by observing others
Monkeys learn correct use of alarm calls
Selection for individual survival and reproductive success can explain most behaviors
Foraging: food-obtaining behavior • Recognize, search for, capturing, and consuming food
• Minimize costs / Maximize benefits
• Costs- energy expenditure and the risk of being eaten
• Crow will drop a whelk (a mollusc) from a height to break its shell
• Trade-off between the height and the number of times it must drop
• Researchers determined total flight height (energy) was minimized at 5 m Average crow flight height: 5.23 m
Mating Behavior & Mate Choice
Sexual selection: seeking and attracting mates, choosing and competing for mates
paternal care by male jawfish
Monogamous species
Polygynous species
Polyandrous species
Promiscuous Monogamous Polygamous (polygynous)
Polyandry
Partners Many One 1 M + many F 1F + many M
Structure Showy Similar Showy male Showy female
Care None Much Male = little Male = none
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Sexual seletion: ornaments correlate in general with health
and vitality
Courtship ritual: elaborate behavior of individuals of the same species before mating
Mate Choice
Males
Agonistic behavior: threats, rituals, and sometimes combat; settles disputes over resources
Females
Mate Choice Copying: copy the mate choice of others
Social Behaviors Competitive Behaviors (pack animals)
• Aggressive behavior: symbolic threat display or a physical struggle between individuals of the same species
• Dominance hierarchy : ranking of individuals in a group based on aggressive behavior
• Territorial behavior: behavior that protects territorial rights
ex: chatting squirrels
marking areas with urine
Genetic Basis of Behavior
• Certain behaviors in prairie voles are under relatively strong genetic control
• ADH (vasopressin) triggers pair-bond formation and aggression by male voles
Differences in oxytocin (a hormone) receptors in 2 species of voles
High oxytocin levels in
prairie voles
(monogomous)
Low oxytocin levels in
montane voles
(promiscuous)
Altruistic Social Behavior
Altruism : selfless behavior
Reduce individual fitness but increase fitness of others in population
i.e. bee societies; naked mole rats
• Inclusive fitness: total effect of producing own offspring (pass on genes) + helping close relatives
• Kin selection: type of natural selection; altruistic behavior enhances reproductive success of relatives
Altruism can be explained by inclusive fitness
Hamilton’s Rule and Kin Selection: quantitative measure for predicting when natural selection would favor altruistic
acts among related individuals
Benefit to the recipient (B)
Cost to the altruistic (C)
Coefficient of relatedness: fraction of genes shared; r
Hamilton’s rule: rB > C
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Example:
Assume the average individual has two children.
As a result of the sister’s action:
• The brother can now father two children, so B 2
• The sister has a 25% chance of dying and not being able to have two children, so C 0.25 2 0.5
• The brother and sister share half their genes on average, so r 0.5
If the sister saves her brother rB ( 1) C ( 0.5)
Game Theory (tit for tat strategy)
- Individuals always cooperate on first encounter
- An individual treats another the same way it was treated the last time they met
• individuals will always cooperate, unless their opponent cheated them the last time they met
• reciprocal altruism
Individuals who engage in a tit-for-tat strategy
have a higher fitness than individuals
who are always selfish
Evolution and Human Culture
• No other species comes close to matching the social learning and cultural transmission that occur among humans
• Human culture is related to evolutionary theory in the distinct discipline of sociobiology
• Human behavior, like that of other species, results from interaction between genes and environment
• However, our social and cultural institutions may provide the only feature in which there is no continuum between humans and other animals
Study for the test!