Introduction to Ecology

Introduction to Ecology

  • Definition: Study of relationships between living organisms and their environment.
  • Focus: Interactions between organisms and surroundings, factors influencing biodiversity.

Levels of Ecological Organization

  • Organism: A single living thing (e.g., one deer).
  • Population: A group of the same species in the same area (e.g., herd of deer).
  • Community: Different populations living together (e.g., deer, rabbits, trees in a forest).
  • Ecosystem: All living and nonliving components in an area (e.g., forest with animals, soil, water).
  • Biome: Large regions with similar climate and ecosystems (e.g., desert, tundra).
  • Biosphere: All life on Earth and the environments they inhabit (land, water, sky).

Components of an Ecosystem: Biotic & Abiotic Factors

  • Biotic Factors: Living components (e.g., plants, animals).
    • Flora: Plant life.
    • Fauna: Animal life.
  • Abiotic Factors: Non-living components (e.g., temperature, water, sunlight).
  • Importance: Determine which organisms can survive in ecosystems.

Types of Ecosystems

Aquatic Ecosystems

  • Marine: Largest oceans, most biodiversity.
  • Freshwater: Low salt concentration; includes lakes, rivers.
  • Swamp/Marsh: Wetlands near rivers or lakes.
  • Estuary: Transition between freshwater and saltwater.
  • Coastal: Interaction of land and water (beaches, coral reefs).
  • Mid-Ocean Ridge: Hydrothermal vents support diverse life via chemosynthesis.

Terrestrial Ecosystems

  • Tundra: Cold, treeless region.
  • Taiga (Boreal Forest): Coniferous forests with cold winters.
  • Temperate Forest: Seasonal trees.
  • Tropical Rainforest: Hot, humid, high biodiversity.
  • Grassland (Prairie): Dominated by grasses.
  • Savanna: Grasslands with scattered trees.
  • Chaparral: Hot dry summers, mild rainy winters.
  • Desert: Arid conditions, sparse vegetation.
  • Island: Isolated with high biodiversity; vulnerable to disruptions.

Food Chains and Food Webs

  • Food Chain: Simple energy flow diagram (e.g., Grass → Grasshopper → Frog → Snake → Hawk).
  • Food Web: Complex interconnection of food chains in an ecosystem.
  • Trophic Levels: Different levels in a food chain (e.g., producers, consumers).
  • 10% Rule: Only 10% of energy is passed to the next trophic level.

Trophic Levels

  • Producers (Autotrophs): Create own food (plants, algae).
  • Consumers (Heterotrophs): Obtain energy by consuming other organisms.
    • Primary Consumers: Herbivores.
    • Secondary Consumers: Carnivores/Olympivores.
    • Tertiary Consumers: Apex predators, no natural enemies.
  • Detritivores: Consume organic matter.
  • Decomposers (Saprotrophs): Break down dead organic matter, recycle nutrients.

Symbiosis

  • Definition: Close interactions between two species.
    • Mutualism: Both species benefit (e.g., bees and flowers).
    • Commensalism: One benefits, other unaffected (e.g., barnacles on whales).
    • Parasitism: One benefits at the expense of another (e.g., ticks and dogs).
  • Coevolution: Different species evolve to rely on each other.

Community Interactions (Interdependence)

  • Predation: Predator hunts and consumes prey.
  • Competition: Organisms compete for resources (food, water, mates).
    • Interspecies: Between different species.
    • Intraspecies: Within the same species.

Ecosystem Stability

  • Concepts: Stability, resistance, and resilience.
    • Stability: Ability to maintain structure and function over time.
    • Resistance: Ability to withstand disturbances.
    • Resilience: Ability to recover after disturbances.
  • Biodiversity: Greater variety of life means a healthier ecosystem.
  • Keystone Species: Species with a disproportionate impact on ecosystem (e.g., wolves in Yellowstone).

Nutrient Cycling

  • Key Cycles: Carbon, nitrogen, phosphorus, and water cycles.
    • Carbon Cycle: Movement through atmosphere, oceans, soil, living organisms.
    • Nitrogen Cycle: Importance for proteins; process includes fixation and assimilation.
    • Phosphorus Cycle: Crucial for nucleic acids and energy; importance and human impact.

Population Ecology

  • Focus: Changes in populations over time (size, distribution).
  • Carrying Capacity: Maximum population an environment can support.
  • Limiting Factors: Constraints on growth (density-dependent and independent).
  • Growth Models:
    • Exponential Growth: Rapid increase (ideal conditions).
    • Logistic Growth: Growth slows near carrying capacity.

Human Impact on the Environment

  • Key Issues:
    • Deforestation and habitat destruction.
    • Overfishing and pollution.
    • Fossil fuel consumption and overpopulation.
    • Invasive species and their impact on native organisms.

Protecting Biodiversity & Conservationism

  • Biodiversity: Important for ecosystem health.
  • Threats: Habitat destruction, pollution, invasive species.
  • Endangered Species: Species at risk of extinction; conservation efforts from organizations.
  • Sustainable Practices: Importance of reducing environmental impact.

Conclusion

  • Key Takeaways: Understanding ecological relationships, the importance of biodiversity, and the impacts of human activities is essential for sustaining ecosystems and protecting the environment for future generations.