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.