Introduction to Ecology & The Biosphere

Introduction to Ecology

  • Ecology: The study of interactions between living organisms and their environment.
    • Essential to understand distribution and abundance of living organisms.
  • Levels of Ecology:
    • Organismal: Focused on individual organisms and their adaptations to the environment.
    • Population: Study of individuals of the same species in a specific area at the same time.
    • Community: Interaction of different species living in the same area.
    • Ecosystems: Includes all living (biotic) and non-living (abiotic) components of an area.

Ecological Levels

  • Organization from individual to ecosystem:
    • Individual Organism → Population → Community → Ecosystem
  • Population: Many individuals of the same species in a specific location.
  • Community: Different populations in a specific locale.
  • Ecosystem: A community combined with abiotic factors.

Four Levels of Ecological Study

  1. Organismal Ecology: Adaptations such as morphological, behavioral, and physiological traits.
  2. Population Ecology: Examines population size and changes over time (e.g., birth/death rates).
    • Conspecifics: Members of the same species.
  3. Community Ecology: Focuses on species interactions (e.g., competition, predation).
    • Heterospecifics: Members of different species.
  4. Ecosystem Ecology: Studies nutrient and energy flow in ecosystems.

Biogeography

  • Biomes: Large areas of land or water with distinct climate, vegetation, and animal life.
  • The collection of biomes is called the biosphere.
  • Studies include:
    • Species distribution based on abiotic factors (e.g., temperature, rainfall).
    • Endemic species: Unique to a specific geographic area.
    • Generalist species: Occupy a wide range of habitats.

Abiotic Factors Affecting Distribution

  • Energy Sources: Sunlight is the primary energy source; plants convert it into chemical energy.
  • Temperature: Affects physiology, water state, and adaptations (e.g., hibernation, migration).
  • Water: Essential for all life; adaptions to conserve water are common in terrestrial organisms.
  • Nutrients and Soil: Nitrogen and phosphorous are vital for plant growth.
  • Oxygen: Varies with elevation and aquatic systems; affects organism survival.
  • Wind and Fire: Affect ecological dynamics and adaptations in various species.

Terrestrial Biomes

  • Influenced mainly by temperature and precipitation.
  • Eight Main Terrestrial Biomes:
    1. Tropical Wet Forest
    2. Savannah
    3. Subtropical Desert
    4. Chaparral
    5. Temperate Grasslands
    6. Temperate Forest
    7. Boreal Forests
    8. Arctic Tundra

Tropical Wet Forest

  • Year-round growth, stable temperatures (20-34°C), high rainfall (125-600 cm).
  • Rich biodiversity.

Savannah

  • Grasslands with scattered trees, average temperatures (24-29°C), minimal rainfall.
  • Fire plays a crucial role in ecosystem dynamics.

Subtropical Desert

  • Extreme temperature swings, negligible rainfall (<2 cm/year).
  • Plants adapt to conserve water.

Chaparral

  • Characterized by scrub forests, subject to periodic fires.
  • Average rainfall (65-75 cm) in winter.

Temperate Grasslands

  • Warm summers, cold winters, plants primarily consist of dense grasses; fire is a regulatory factor.

Temperate Forest

  • Dominated by deciduous trees, predictable rainfall (75-150 cm annually), distinct seasons.

Boreal Forest (Taiga)

  • Cold, wet summers, long, dry winters with low nitrogen soil; thin conifer tree diversity.

Arctic Tundra

  • Extremely low temperatures (-34 to 3°C); vegetation includes shrubs, permafrost present.

Aquatic Biomes

  • Freshwater: Lakes, ponds, rivers — categorized by flow and vegetation.
  • Marine: Ocean regions, coral reefs, and estuaries.
    • Light penetration significantly impacts life forms.

Marine Biomes

  • Ocean: Largest biome; divided into zones based on light.
  • Coral Reefs: Symbiotic relationships; high biodiversity threatened by climate change.
  • Estuaries: Where saltwater and freshwater meet — rich in nutrients but low biodiversity due to salinity variations.

Freshwater Biomes

  1. Lakes and Ponds: Thermal stratification affects nutrient cycling and algae growth.
  2. Rivers and Streams: Flow rates influence composition and community structure.
  3. Wetlands: Saturated soils, differing from lakes; critical biodiversity hotspots; include marshes and swamps.