Biotic and Abiotic Factors Affecting Species Distribution

Biotic and Abiotic Factors Affecting Species Distribution

Introduction

  • Biotic and Abiotic Factors

    • Biotic Factors: Interactions among living organisms that affect species distribution.

    • Abiotic Factors: Non-living environmental variables that influence where species can thrive.

  • Biogeography: The study of the distribution of organisms and the underlying causes behind where they are found.

Factors Affecting Species Distribution

Biotic Factors

  • Definition: Refers to “living” interactions among organisms, which encompasses various types of relationships and effects.

  • Characteristics:

    • Pollination: Positive effect (+) on species distribution, facilitating reproduction in plants.

    • Predation: Negative effect (−) where one species consumes another, impacting organism populations.

    • Parasitism: Negative effect (−) where one organism benefits at the expense of another by feeding off it.

  • Notes: These biotic interactions are analyzed in greater depth in community ecology lectures.

Abiotic Factors

  • Definition: Refers to non-living variables that impact species distribution. Key aspects include:

    • Temperature:

    • Most organisms thrive within a narrow temperature range because of thermal limitations.

    • Key Points:

      • Freezing Point of Water: 0°C

      • Boiling Point of Water: 100°C (varies with elevation)

      • Protein Denaturation: Occurs around 45°C (113°F), rendering proteins inactive, affecting organism viability.

      • Importance of water content in organisms: Most are primarily composed of water (e.g., humans are approximately 67% water).

    • Water:

    • Essential to life; no known organism can survive without water.

    • Role of water: Vital for biological processes and maintaining ecological balance.

    • Organisms far from water sources demonstrate extreme adaptations to survive in arid environments.

    • Oxygen:

    • Critical for respiration in aerobic organisms, although not all species require it.

    • Water's role: Oxygen diffusion is slower in water, leading to decreased availability, influencing aquatic life.

    • Sunlight:

    • Major source of energy on Earth with most life reliant on photosynthesis.

    • Importance: Insufficient sunlight limits photosynthesis, particularly in environments like caves.

    • Human Health Warning: Excessive sunlight exposure can cause DNA damage, illustrated by real-life examples such as skin cancer risks for lifeguards.

    • Rocks and Soil:

    • Influence vegetation growth patterns, thus affecting animals that feed on plants.

    • Factors affecting soil quality include:

      • pH levels

      • Mineral composition

      • Soil texture and rock presence

    • Impact on water chemistry: Rocks and soil can influence the chemical composition of water bodies.

    • Salinity and Osmosis:

    • Salinity: Refers to the concentration of salts in water, affecting the water balance of organisms via osmosis (the process of water diffusion).

    • Importance: Understanding salinity is critical for aquatic organisms and is elaborated upon in a separate mini-lecture.