Animal Behavior (Ch. 51): Mechanisms, Learning, and Evolutionary Basis

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Behavior is an action carried out by muscles under control of the nervous system in response to a stimulus.
Behavior is a complex function of an organism, integrating sensory input, neural processing, and motor output.
Major categories of behavior include:
- Foraging behavior
- Reproductive behavior
- Social behavior
- Navigation
- Antipredator behavior

Animals use a variety of signals to communicate, which can be visual, auditory, tactile, or chemical.

Visual communication: Important for diurnal species; less so for nocturnal animals.
Auditory communication: Sound signals, such as bird songs or insect calls.
Tactile communication: Touch, such as grooming or tapping.
Chemical communication: Use of pheromones—molecules released into the environment to communicate with members of the same species.

Example: Minnows release an alarm substance (pheromone) when wounded, causing other minnows to exhibit antipredator behavior.

Proximate cause: How a behavior occurs or is modified (stimuli and physiological mechanisms).
Ultimate cause: Why a behavior occurs in the context of natural selection (adaptive value).
Example: Minnows' alarm response is triggered by chemical cues (proximate), which increases survival (ultimate).

Level of Question	Contemporary (Present Day)	Historical (Sequence of Events)
Proximate (How?)	Mechanism (Causation): How does it work?	Development (Ontogeny): How did it develop?
Ultimate (Why?)	Function (Adaptive Value): What is it for?	Evolution (Phylogeny): Why did it evolve?

Mechanism: What causes the behavior? (e.g., pheromones, hormones)
Development: How does the behavior develop over an individual's lifetime? (e.g., learning, experience)
Function: How does the behavior increase fitness? (e.g., survival, reproduction)
Evolution: How did the behavior evolve? (e.g., comparative studies among species)

Bee Waggle Dance: Communicates location of food sources to other bees (visual communication).
Round Dance: Indicates food is nearby (within 50 m).
Innate Behavior: Inborn, not learned, with a fixed pattern (e.g., spiders building webs).

Fixed Action Pattern (FAP): A sequence of unlearned acts directly linked to a simple stimulus.
Sign Stimulus: An external cue that triggers the FAP (e.g., red belly in male sticklebacks triggers aggression).

Migration: Long-distance movement guided by environmental cues (sun, stars, Earth's magnetic field).
Behavioral Rhythms:
- Circannual rhythms: Yearly cycles, often related to seasons.
- Lunar cycles: Monthly cycles, often related to tides.
- Circadian rhythms: Daily cycles, such as sleep-wake patterns.

Learning: Modification of behavior based on experience.
Cross-fostering studies: Used to determine the influence of environment on behavior (e.g., aggression and parental care in mice).

Species	Aggression Toward Intruder	Aggression in Neutral Situation	Parental Behavior
California mice fostered by white-footed mice	Reduced	No difference	Reduced
White-footed mice fostered by California mice	No difference	Increased	No difference

Imprinting: Formation of a long-lasting behavioral response to a specific individual or object at a particular stage in life (sensitive period).
Imprinting is innate and developmentally fixed.
Example: Young geese following the first moving object they see (often their mother).

Spatial learning: Establishment of a memory that reflects the spatial structure of the environment.
Cognitive map: A mental representation of spatial relationships between objects.
Example: Wasps using landmarks to locate their nests.

Associative learning: Ability to associate one environmental feature with another.
Operant conditioning: Learning to associate one's own behavior with a reward or punishment.
Classical conditioning: An arbitrary stimulus becomes associated with a particular outcome (e.g., Pavlov's dogs salivating at the sound of a bell).

Cognition: Process of knowing that involves awareness, reasoning, recollection, and judgment.
Problem solving: Ability to devise a method to overcome obstacles (e.g., navigating mazes).

Most behaviors are influenced by genes, which have evolved through natural selection.
Example: Prey selection in snakes is genetically determined.

Foraging behavior: Searching for and acquiring food.
Optimal foraging model: Natural selection favors behaviors that maximize benefits and minimize costs (energy, risk).
Example: Fruit fly larvae with different alleles forage at different distances depending on population density.

Mating systems:
- Monogamy: One male, one female.
- Polygamy: One individual mates with several others (includes polygyny and polyandry).
- Promiscuity: No strong pair bonds.
Sexual dimorphism: Differences in appearance between males and females, often related to mating system.
Parental care: Certainty of paternity influences male parental investment.
Sexual selection: Includes intrasexual competition (male-male) and intersexual choice (female choice).
Mate choice copying: Individuals copy the mate choices of others.
Game theory: Evaluates alternative strategies where the outcome depends on the strategies of all individuals involved (e.g., frequency-dependent selection in lizards).

Inclusive fitness: An individual's genetic success is derived from cooperation and altruistic behavior that benefits relatives.
Altruism: Behavior that reduces an individual's fitness but increases the fitness of others.
Hamilton's Rule: Altruism is favored when , where is the coefficient of relatedness, is the benefit to the recipient, and is the cost to the altruist.
Kin selection: Natural selection that favors altruistic behavior toward close relatives.
Reciprocal altruism: Altruism toward unrelated individuals, with the expectation of future reciprocation; common in stable social groups.

Relationship	Coefficient of Relatedness (r)
Parent-offspring	0.5
Siblings	0.5
Aunt/Uncle-Niece/Nephew	0.25
First cousins	0.125

Example: Naked mole rats exhibit extreme altruism, with non-reproductive individuals sacrificing themselves for the colony's queen.

Concept	Definition	Example
Innate behavior	Inborn, not learned, fixed pattern	Spider web building
Fixed action pattern	Sequence of unlearned acts triggered by a sign stimulus	Stickleback fish attacking red objects
Sign stimulus	External cue triggering a behavior	Red belly in sticklebacks
Imprinting	Long-lasting response formed during a sensitive period	Geese following first moving object
Operant conditioning	Learning via reward or punishment	Rat pressing lever for food
Classical conditioning	Association of arbitrary stimulus with outcome	Pavlov's dogs salivating at bell
Optimal foraging	Maximizing benefit, minimizing cost in food search	Fruit fly larval foraging distance
Kin selection	Favoring relatives in altruistic acts	Alarm calls in ground squirrels