Post on 24-May-2020
Animal Behavior (Ch. 51)
Behavioral Ecology
Two types of questions:
Proximate questions: Focus on environmental stimuli that trigger behavior and physiology behind response
“How?”
Ultimate questions: Focus on evolutionary significance of the behaviors
Why?”
Proximate Questions
Proximate questions address the mechanisms that produce a behavior.
The environmental stimuli, the genetic and physiological mechanisms that make it possible
Example- How does an animal carry out a particular behavior?
Red-crowned cranes breed in spring and early summer. Choose the proximate explanation:
A. Breeding is most likely to be successful in spring and early summer.
B. Increasing day length triggers the release of breeding hormones.
C. Ample food is available for chicks at this time.
Ultimate Questions
Ultimate questions address the evolutionary significance of a behavior
How a behavior increases the evolutionary fitness of the animal demonstrating it, helping it to survive and reproduce in its environment.
Example- Why does the animal show this behavior?
What is evolutionary fitness?
Adaptive behavior
An adaptive behavior increases an individual’s evolutionary fitness relative to other individuals in the population. (Similar to a physical adaptation)
Red-crowned cranes breed in spring and early summer. Choose an ultimate
explanation:
A. Breeding is most likely to be successful in spring and early summer.
B. Hormonal changes in the spring trigger breeding behaviors.
C. Breeding is triggered by the effect of increased day length on the birds’ photoreceptors.
Sexual cannibalism
In some species, one sex (usually the female) consumes the other during sexual reproduction.
Australian redback spiderPraying mantis Scorpion
Australian Redback Spider
Praying Mantis
Choose a proximate explanation for female cannibalism:
A. The female eats the male as he dangles his abdomen in front of her jaws.
B. The female can produce a larger egg sac if she eats the male.
C. The female gains nutrients by eating her mate.
Choose an ultimate explanation for female cannabilism:
A. The female eats the male because he dangles his abdomen in front of her jaws.
B. The female gains nutrients from eating the male.
C. The female copulates longer while eating her mate.
Choose a proximate explanation for male self-sacrifice:
A. The male’s somersault in front of the female’s jaws is triggered when he inserts a palp in the female’s sperm receptor.
B. The male is providing nutrients to his offspring.
C. A male that is cannibalized fathers twice as many offspring.
Choose an ultimate explanation for male self-sacrifice:
A. The male increases the length of copulation by sacrificing himself.
B. The male’s self-sacrifice is an innate, genetically programmed behavior.
C. The male is providing nutrients to his hungry mate.
Further testing…
- What experiment might you conduct that would narrow down the ultimate cause choices above?
Behavioral Ecology
Behavior= What an animal does and how the animal does it
Ethology= Study of how animals behave, particularly in their natural environment
Behavioral Basics
Behavioral Ecology
Based on idea that animals behave in such a way as to maximize fitness
Idea only works because genes influence behavior (nature)
Fitness= Passing on genes to offspring
Animals modify behavior to keep ratio of energy intake to energy expenditure high
Ex. chipmunks
Review: Optimal Foraging
Amount of food taken in will be in proportion to amount of energy spent
What is the relationship to fitness?
Scientific Research
EthologistsNikolaas Tinbergen
Nobel Prize- Eliciting behavior patterns in animals
Four Questions
Mechanical- How does the behavior occur?
Developmental- How has the behavior changed?
Evolution- How did this behavior come about?
Fitness- Why is this behavior beneficial?
EthologistsKarl von Frisch
Discovered the communication dance of bees
Round dance meant food was close
“Waggle” dance showed distance and direction of food
Konrad LorenzWorked with greylag geese and discovered imprinting
Ethnologists
Innate Behaviors
Fixed Action Pattern (FAP)
Sequence of unlearned, unchangeable behaviors
Usually carried to completion once started
Triggered by external event = sign stimulus
Ex. Stickleback fish- Tinbergen
Fixed Action Patterns (FAP)
Egg rolling experiment
Directed MovementsTaxis
Change in direction
Automatic movement toward (positive taxis) or away from (negative taxis) a stimulus
Phototaxis
Chemotaxis
Geotaxis
Kinesis
Change in rate of movement in response to a stimulus
Complex Innate BehaviorsMigration
“Migratory restlessness” seen in birds bred & raised in captivity
Navigate by sun, stars, Earth’s magnetic fields
Imprinting- Innate & Learned
Learning to form social attachments at a specific critical period
Both learned and innate components
ImprintingGenerally irreversible
Has critical period/sensitive period = limited time when behavior can be learned
Ex. geese- Konrad Lorenz
Review• Optimal foraging• Scientists - Von Frisch, Lorenz, Tinbergen• Innate Behaviors
• FAP• Directed movements• Migration• Imprinting
Learned Behaviors
LearningModification of behavior based on experiences
Habituation= Lack of response to stimuli that give no information
Spacial Learning= Based on experience with structure of environment
Associative Learning= Connecting one event with another
Classical Conditioning
Operant Conditioning
Learning: Habituation“Cry wolf ” effect
Decrease in response to repeated occurrences of stimulus
Enables animals to disregard unimportant stimuli
Why?
Ex. falling leaves not triggering a response in baby birds
Spatial Learning • Memory reflected by environment’s spatial
structure • Ex. Digger wasps, hidden food sources, etc.
Associative Learning • Classical conditioning- Unconnected stimulus
associated with specific outcome • Ex. Pavlov’s salivating dogs and a bell
• Operant conditioning- Trial and error; behavior associated with specific outcome • Ex. Skinner’s mouse and food lever
Operant Conditioning
https://www.youtube.com/watch?v=H6LEcM0E0io
Social Behaviors
Social BehaviorsInteractions between individuals
develop as evolutionary adaptations
communication/language, agonistic behaviors, dominance hierarchy, cooperation, altruistic behavior
Agonistic BehaviorsThreatening & submissive rituals
symbiotic, usually no harm done
ex. territoriality, competitor aggression
Dominance HierarchySocial ranking with a group
pecking order
Cooperation
Working together in coordination
Ex. pack of African dogs hunting a wildebeest, white pelicans herding fish
Altruistic behavior
Reduces individual fitness, but increases fitness of recipient
Increasing survival of close relatives passes familial genes on to the next generation
Animal Signals
Visual
Auditory
Chemical
Tactile/touch