Unit 7: Ecology and Behavior (Part V: Animal Behavior) – General Biology Study Notes

Behavior in Animals

Definition and Types

Animal behavior refers to any observable action, movement, or activity of organisms in response to a stimulus. Behaviors are crucial for survival, reproduction, and interaction with the environment. There are two main types of behavior: innate behavior and learned behavior.

• Innate behavior: Genetically programmed, heritable, and performed correctly without prior experience.

• Learned behavior: Developed or changed as a result of experience.

Stimulus

A stimulus (plural: stimuli) is any change in the internal or external environment that elicits a response from an organism.

• External stimuli: Light, food, temperature, other animals.

• Internal stimuli: Hormones, enzymes, hunger, emotion.

Explaining the Causes of Behavior

Proximate vs. Ultimate Causes

Behavioral biologists distinguish between two levels of explanation for animal behavior:

• Proximate cause: The immediate, mechanistic reason for a behavior (e.g., gene expression, physiology, development).

• Ultimate cause: The evolutionary reason for a behavior (e.g., adaptive value, phylogeny, evolution).

Example: Zebras running away after hearing an alarm call.

• Proximate cause: Alarm call triggers fear in the brain, causing rapid escape.

• Ultimate cause: Alarm call signals danger (predators), so running away increases survival.

General Mechanism of Behavior in Animals

Animal responses to stimuli follow a general pathway:

• Stimulus → Sensory receptor → Integration unit (brain, spinal cord, ganglia) → Effector (muscles, glands) → Behavior

Innate Behavior

Characteristics

• Performed correctly at first attempt

• Genetically programmed and heritable

• All members of a species perform the behavior similarly

Examples of Innate Behavior

• Orientation: Alteration of body position or movement direction in response to a stimulus

  • Kinesis: Random movement rate changes (e.g., woodlice move more in dry areas)

  • Taxis: Directed movement toward or away from a stimulus (e.g., fish swimming toward light)

  • Types of taxis:

    • Phototaxis: response to light

    • Chemotaxis: response to chemicals/odors

    • Rheotaxis: response to fluid flow

    • Geotaxis: response to gravity

    • Phonotaxis: response to sound

• Reflex: Involuntary, nearly instantaneous response to a stimulus (e.g., knee-jerk reflex, gag reflex, rooting/sucking/swallowing reflexes in newborns)

• Fixed Action Pattern (FAP): Highly stereotyped, innate sequence of behaviors triggered by a specific stimulus (e.g., egg-retrieval in graylag goose)

• Sign stimulus (releaser): The specific component of a stimulus that triggers a FAP (e.g., red color in stickleback fish triggers aggression)

• Courtship behavior: Species-specific actions/signals to attract mates

• Nest building: Construction of nests by birds and other animals

Genetic Basis of Behavior

• Single genes can affect complex behaviors (e.g., fosB gene in mice influences parental care)

Learned Behavior

Characteristics

• Developed or changed through experience

• Flexible and adaptable

Types of Learned Behavior

• Habituation: Gradual reduction or cessation of response to a repeated, irrelevant stimulus

• Imprinting: Rapid, irreversible learning at a specific life stage, leading to strong attachment (e.g., ducklings following the first moving object they see)

• Associative learning (conditioning):

  • Classical conditioning: Association of a neutral stimulus with an unconditioned stimulus to elicit a response (e.g., Pavlov's dogs)

  • Operant conditioning: Association of behavior with consequences (reinforcement or punishment); involves trial-and-error learning (e.g., Skinner box)

• Insight: Use of reasoning and previous experience to solve new problems; common in intelligent animals (e.g., chimpanzees, crows, dolphins)

• Social learning: Learning through interactions with others, such as observing, imitating, teaching, or playing

• Copying (imitation): A type of social learning where individuals replicate the actions of others

Genotype, Phenotype, and Behavior

• Genotype: Genetic makeup of an organism

• Phenotype: Observable traits, including behavior

• Both innate and learned behaviors are influenced by genes and environment

• Main difference: innate behaviors do not require experience; learned behaviors do

Comparison Table: Innate vs. Learned Behavior

Feature	Innate Behavior	Learned Behavior
Occurrence	Short-lived animals	Long-lived animals with complex nervous systems
Flexibility	Fixed	Flexible
Experience Required	No	Yes
Function	Survival, escape from danger	Adaptation to environment

Migration

Definition and Features

Migration is the regular, back-and-forth movement between two distant areas, usually occurring annually. It allows animals to access more abundant resources or escape unfavorable conditions.

• Can be innate or learned, depending on the species

• Examples: Monarch butterflies, birds, whales

Social Relations and Group Living

Social Behavior

Social behavior involves interactions between individuals of the same species, including conflict, cooperation, mating, courtship, parental care, nest building, and cooperative hunting.

Social Animals

• Species living in permanent groups and exhibiting complex social behaviors

• Examples: Bees, ants, termites, lions, dolphins, dogs, monkeys, humans

Group Living Benefits

Benefit	Description
Foraging	Improved efficiency in finding food
Anti-predator	Protection from predators (e.g., circle defense, aggregation)
Mating opportunity	Increased chances of finding mates
Other	Parental care, cooperative hunting, etc.

Examples: Circle defense in musk oxen, aggregation in zebras, spawning in fish, cooperative hunting in lions.