Animal Behavior Final
Introduction
Developing Mutually Exclusive Hypotheses with Testable Predictions
Hypotheses should be clear statements that offer alternative explanations for the phenomenon being studied.
Predictions should follow logically from each hypothesis, and be testable using observations or experiments.
If one hypothesis is supported, the other should be refuted (mutually exclusive).
Proximate vs. Ultimate Questions
Proximate questions focus on the immediate mechanisms underlying a behavior, addressing how a behavior occurs.
Ultimate questions focus on the evolutionary reasons for a behavior, addressing why a behavior has evolved.
Example: For the question, "Why do birds sing?", a proximate question could be "What hormonal changes trigger birdsong?", while an ultimate question could be "How does birdsong increase a bird's fitness?".
Tinbergen's Four Questions
Causation/Mechanism: What physiological mechanisms cause the behavior?
Development/Ontogeny: How does the behavior develop during an individual's lifetime?
Function/Adaptation: How does the behavior contribute to the individual's survival and reproduction?
Evolution/Phylogeny: How did the behavior evolve across generations and what is its evolutionary history?
Example: For birdsong, Tinbergen's four questions could be:
Causation: What are the neural and muscular mechanisms of song production?
Development: How does birdsong develop over a bird's lifetime and is it learned or innate?
Function: How does birdsong help birds attract mates and defend territories?
Evolution: How has birdsong evolved across different bird species and what are its ancestral forms?
History of Behavior
Evolution and its assumptions
Definition of Evolution: The change in allele frequencies within a population over time.
Assumptions of Evolution:
Variation: Individual offspring vary in their traits.
Heritability: This variation is heritable, meaning it can be passed from parents to offspring.
Differential Reproduction: Individuals with heritable variations that provide an advantage in survival or reproduction are more likely to pass those variations on to subsequent generations.
Fixed Action Patterns (FAPs)
Definition: An instinctive, stereotyped behavioral sequence that is triggered by a specific stimulus and runs to completion once initiated.
Sign Stimulus: The specific stimulus that triggers a FAP.
Releaser: A sign stimulus emitted by a member of the same species.
Innate Releasing Mechanism (IRM): A hypothetical neural mechanism that detects the sign stimulus and triggers the FAP.
Supernormal Stimulus: An exaggerated version of the sign stimulus that elicits a stronger response than the natural stimulus.
Example: The red belly of a male European robin is a sign stimulus that triggers aggression in other males. An isolated clump of red feathers can act as a supernormal stimulus, eliciting a stronger aggressive response.
Behavioral Genetics
Influences on Behavior: Genetics vs. Environment
Genotype: An organism's genetic makeup.
Phenotype: An organism's observable characteristics, influenced by both genotype and environment.
Heritability: The proportion of phenotypic variation in a population that is due to genetic variation.
Methods of Studying/Influencing Genetics
Inbreeding: Creating genetically similar strains to minimize genetic diversity within strains and maximize it between strains. This helps isolate environmental effects on behavior.
Hybridization: Crossing different strains or species to examine the genetic basis of behavioral differences.
Artificial Selection: Selectively breeding individuals with desired traits to see how those traits change over generations.
Genetic Transformation: Using techniques like gene knockouts or gene transfers to directly manipulate genes and assess their effects on behavior.
Narrow Sense vs. Broad Sense Heritability
Narrow Sense Heritability (h2): Measures the proportion of phenotypic variation due to additive genetic variance. It is calculated as the response to selection (R) divided by the selection differential (S).
Broad Sense Heritability (H2 or 0GD): Measures the proportion of phenotypic variation due to all genetic variation, including additive, dominance, and epistatic effects. It is calculated as the genetic variance (Vg) divided by the total phenotypic variance (VT), where VT is the sum of genetic variance (Vg) and environmental variance (Ve).
Hormones
Mechanisms of Hormonal Influence on Behavior
Sensory/Perceptual Mechanisms: Hormones can influence the ability to detect stimuli, the response to stimuli, and preferences for certain stimuli.
Development/Activity of CNS Neurons: Hormones can affect the development and activity of neurons in the central nervous system, leading to changes in brain structure and function.
Muscles Involved in Behavior: Hormones can act on muscles and motor neurons to directly influence the execution of behavior.
Organizational vs. Activational Effects
Organizational Effects: Occur early in development (prenatally or shortly after birth/hatching) and permanently alter the organization of neural pathways responsible for specific behaviors.
Activational Effects: Occur in adulthood, are transient (lasting only as long as hormone levels are high), and involve subtle changes in previously established neural connections to trigger specific behaviors.
Nervous System
Sensory System Overview
Sensory receptors detect stimuli from the environment.
This information is then transmitted to the central nervous system via afferent pathways.
The central nervous system processes this information and generates appropriate responses.
Feature Extraction/Filtering of Sensory Input
Feature Extraction: The process by which the nervous system identifies and isolates specific features of a sensory stimulus, such as edges, lines, or movement.
Filtering: The nervous system selectively filters out irrelevant information and focuses on the most salient features of a stimulus.
Example: "Worm" and "anti-worm" cells in the visual system of frogs respond selectively to moving stimuli with specific characteristics, allowing them to detect prey while ignoring other visual information.
Behavioral Development
Five Factors Influencing Development
While the sources do not explicitly list five factors influencing development, the key concept is that development is influenced by a complex interplay of genetic and environmental factors.
Impact of Early Developmental Factors on Adult Behavior
Experiences and environmental conditions during early development can have long-lasting effects on behavior.
Example: Birdsong learning in many species occurs during a critical period early in life. Exposure to appropriate song models during this period is essential for the development of normal song.
Signals and Communication
Definition of Communication
A signal sent by a sender that benefits the sender, on average, by altering the receiver's behavior.
Quantifying/Measuring Information
Information Content (H): Measured in bits, represents the reduction in uncertainty about a particular event or message.
Formula: H = log2 n, where n is the number of equally probable alternatives.
Example: Fire ant trails reduce the uncertainty about the location of food by 4 bits. This means there are 16 equally probable directions the ants could travel, and the trail eliminates uncertainty about which direction is correct.
Types of Communication Based on Benefit/Cost
Mutualistic: Both sender and receiver benefit from the communication.
Altruistic: Sender incurs a cost while receiver benefits.
Spiteful: Both sender and receiver incur a cost.
Manipulative: Sender benefits while receiver incurs a cost.
Main Types of Communication
Visual Communication: Using sight to send and receive signals (color, patterns, movement).
Advantages: Long-range, easily locatable, fast.
Disadvantages: Requires daylight, difficult in dense environments, potentially costly, conspicuous to predators.
Acoustic Communication: Using sound to send and receive signals.
Advantages: Long-range, effective day or night, low energy to produce.
Disadvantages: Signal competition, attenuation in dense habitats, potential vulnerability to predators.
Tactile Communication: Using touch or vibrations to send and receive signals.
Advantages: Direct, unambiguous sender identification.
Disadvantages: Short-range, potentially risky.
Chemical Communication: Using pheromones and other chemical signals.
Advantages: Can be long-lasting, can travel long distances.
Disadvantages: Slow transmission, susceptible to environmental factors.
Electrical Communication: Using electrical fields to send and receive signals (mainly in aquatic environments).
Advantages: Effective in murky water where other modalities are limited.
Disadvantages: Short-range, cells need to reset after impulses.
Honest vs. Dishonest Signals
Honest Signals: Convey accurate information about the sender, typically when:
Sender and receiver share overlapping goals.
Signal is difficult to fake.
Signal is costly to produce.
Dishonest signalers can be identified.
Dishonest Signals: Mislead the receiver, typically when:
Sender and receiver have conflicting goals.
Signal is costly to assess or challenge.
Learning
Types of Learning and Favored Contexts
Environmental Sensitivity/Imprinting: Learning that occurs during a specific sensitive period early in life and is typically irreversible.
Favored when: Information is stable and predictable, learning early is crucial for survival.
Individual Learning: Learning through experience, independent of social interactions.
Favored when: Environmental conditions are variable, individual exploration and problem-solving are beneficial.
Social Learning: Learning from observing the behavior of others.
Favored when: Environmental conditions are stable but learning individually is costly, social interactions are frequent.
Conditioning
Classical Conditioning: An animal learns to associate an initially neutral stimulus with a biologically significant stimulus, resulting in a conditioned response.
Example: Pavlov's dogs learning to salivate at the sound of a bell.
Operant Conditioning: An animal learns to associate its own voluntary behavior with a consequence (reward or punishment), leading to increased or decreased frequency of that behavior.
Example: A rat learning to press a lever to receive food.