Fix the mistake: Animal Behavior

Innate Behavior and Fixed Action Patterns

Animal behavior is broadly divided into genetically programmed innate behavior (instinctive behavior) and learned behavior acquired through experience. Innate behavior is a stereotyped response that appears automatically in response to a specific stimulus and is adaptive behavior directly related to survival and reproduction. First, let us learn about the structure and representative examples of innate behavior.

Basic Knowledge

Characteristics of innate behavior: ① Genetically determined ② Does not require experience or learning ③ Species-specific, with nearly all individuals of the same species showing almost identical patterns ④ Limited flexibility in responding to the environment.

Fixed action pattern (FAP): A concept proposed by Lorenz and Tinbergen. It is triggered by a specific sign stimulus (releaser) and, once started, is carried out to completion even if the stimulus is removed. Internal instinctive energy (motivation) accumulates and is released by the sign stimulus (hydraulic model). Examples: herring gull chicks pecking at the red spot on a parent bird's beak, and male three-spined sticklebacks attacking red objects.

Taxis: A directed response in which the whole body is oriented toward the direction of a stimulus. Examples: phototaxis, chemotaxis, and geotaxis.

Reflex: The simplest innate behavior. Spinal reflexes such as the patellar tendon reflex are typical examples. Unlike an FAP, a reflex can be stopped partway through.

Tinbergen's four questions: He stated that the study of behavior requires both the perspectives of ① proximate causes (mechanisms and development) and ② ultimate causes (evolutionary function and evolutionary history).

Example Problem
Explain the territorial behavior of male three-spined sticklebacks using the concept of a fixed action pattern (FAP).
Answer: During the breeding season, the abdomen of a male three-spined stickleback turns red. When another male enters its territory, the red abdomen acts as a sign stimulus that releases an FAP, automatically causing stereotyped attack behavior toward the intruder. In experiments, the fish also attacks a model painted red, but does not attack even a highly realistic model if it is not red. In other words, the sign stimulus of “redness” releases the behavior.
Key Points
  • Innate behavior = genetically programmed and does not require experience
  • FAP = released by a sign stimulus and carried out to completion once begun
  • Sign stimulus (releaser) = a specific stimulus that releases an FAP
  • Lorenz and Tinbergen = fathers of ethology
  • Taxis = directed movement in response to the direction of a stimulus, such as phototaxis
  • Reflex = the simplest innate behavior and can be stopped partway through
  • Tinbergen's four questions = the proximate-cause and ultimate-cause perspectives

Points to Note

① Difference between an FAP and a reflex: an FAP continues even if the stimulus is removed after it begins, whereas a reflex stops when the stimulus disappears. ② Innate behavior and learned behavior are not opposites; many behaviors contain components of both. ③ Do not confuse taxis with tropism (directed growth in plants).

Practice

  1. State the definition of a fixed action pattern (FAP) and the name of the stimulus that triggers it.
  2. Give two examples of taxis and describe the stimulus to which each is a response.
  3. Explain the difference between proximate and ultimate causes in Tinbergen's “four questions of behavior.”

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