Responses to the Environment

Responses to the Environment

  • Key Concept: Understanding animal behavior in response to external stimuli.

Behavioral Ecology

  • Ethology:

    • Study of evolutionary processes shaping animal behavior and responses to stimuli.
    • Awarded Nobel Prize in Physiology in the 1970s.

  • Behavior Defined:

    • Response of an animal to internal or external stimuli.
    • Subject to genetic (nature) and environmental (nurture) factors.
    • Influences survival and reproduction, thus affected by natural selection.

Understanding Behavior

  • Two Types of Causes for Behavior:
    • Proximate Cause (How?):
    • Immediate stimulus causing the behavior.
    • Influence of nurturing experiences during development on behavior.
    • Ultimate Cause (Why?):
    • Evolutionary significance of the behavior.
    • Survival and reproductive advantages derived from the behavior.

Proximate vs Ultimate Questions

  • Proximate (How?): Mechanism & Development
  • Ultimate (Why?): Function & Evolution
  • Level of Questions:
    • Contemporary: Current behavior mechanisms.
    • Historical: Evolutionary pathway of behaviors.

Example of Behavior Analysis: Zebras at Water Holes

  • Proximate Cause: Awareness of surroundings, alertness created by hunger or thirst urges.
  • Ultimate Cause: Evasion of predators enhancing survival odds.

Types of Behavior

  • Innate vs Learned:
    • Innate Behaviors:
    • Developmentally fixed, instinctual, hereditary.
    • Triggers: Fixed action patterns linked to stimuli (e.g., stickleback aggression).
    • Learned Behaviors:
    • Influenced by environmental experiences.
    • Varied across populations (e.g., birds finding nests using spatial maps).

Examples of Innate Behaviors

  • Fixed Action Patterns (FAPs):

    • Triggered by sign stimuli, unlearned acts completed without deviation.
    • Example: Male stickleback fish reacting aggressively to the color red.

  • Migration: Long-distance relocation induced by environmental cues such as the sun's position.

  • Animal Communication Signals:

    • Pheromones and stimulus-response chains facilitating mating (e.g., waggle dance of bees).

Learning Behaviors

  • Imprinting: Long-lasting responses formed during a sensitive developmental period (e.g., ducklings following their mother).
  • Spatial Learning: Memory formation based on environmental layout (e.g., birds hiding nests).
  • Associative Learning: Linking environmental features (e.g., foul taste of monarch butterflies).
  • Social Learning: Observational learning through mimicry (e.g., chimpanzees using tools).

Natural Selection and Behavior

  • Behavior Optimization: Natural selection favors behaviors maximizing survival and reproduction (e.g., successful foraging).
  • Mating Behaviors: Influenced by sexual selection leading to sexual dimorphism.
  • Cooperative Behaviors: Examples include warning calls and altruism, increasing group fitness.
    • E.g., naked mole rats' social structure supporting reproductive roles.

Plant Responses to Environment

  • Phototropism: Growth direction toward light sources.
  • Photoperiodism: Timing of flowering based on day length.
  • Defensive Mechanisms: Physical defenses (thorns) and chemical defenses (toxins).
    • Example: Lima beans sensing damage to release protective compounds.
  • Soil pH Effects: pH altering flower colors (e.g., hydrangeas).

Examples of Behavior Analysis: Ravens Feeding

  • Proximate Cause: Loud vocalizations attracting others, enhancing feeding opportunities.
  • Ultimate Cause: Increased food access leads to shared foraging success.
  • Comparison with other species where food defense is common and the reasoning behind it (e.g., ensuring survival against competitors).