Ecosystem Interactions and Biodiversity

Levels of Organization

  • Organism: Individual living thing.
  • Population: Group of the same species living together.
  • Community: Group of different species in a given area.
  • Ecosystem: Interactions of all biotic (living) and abiotic (nonliving) factors in an area.
  • Biome: Major global/regional community, characterized by climate and plant communities.
  • Biosphere: All environments on Earth that support life.

Biotic vs. Abiotic Factors

  • Biotic Factor: Living organisms influencing an ecosystem.
  • Abiotic Factor: Nonliving conditions influencing organism survival.

Habitat vs. Niche

  • Habitat: Describes the environment where an organism lives, including biotic and abiotic factors.
  • Niche: The role of an organism in its ecosystem; factors affecting its survival.
    • Example: Polar Bear Habitat: Arctic regions with ice and snow.
    • Example: Polar Bear Niche: Predation on seals, adaptation to cold climate.

Keystone Species

  • Definition: A species that has a disproportionately large effect on its ecosystem, analogous to a keystone in an arch.
  • Impact: Removal of a keystone species can disrupt the entire ecosystem.

Energy in Ecosystems

  • Autotrophs (Producers): Organisms that make their own food (e.g., via photosynthesis or chemosynthesis).
    • Chemosynthetic Organisms: Obtain energy from inorganic compounds, often found near hydrothermal vents.

Food Chains/Food Webs

  • Food Chain: Linear sequence showing energy transfer from one trophic level to another.
  • Food Web: Complex interconnected feeding relationships.
  • Trophic Levels:
    1. Producers (1st Trophic Level)
    2. Primary Consumers (2nd Trophic Level)
    3. Secondary Consumers (3rd Trophic Level)
    4. Tertiary Consumers (4th Trophic Level)

Energy Pyramid

  • Energy transfer between trophic levels results in significant losses (approx. 90% as heat).
    • Only about 10% of energy is transferred to the next level.
  • Comparison of energy, biomass, and population at each trophic level:
    • Primary Producers: Largest energy input, lowest trophic level.
    • Tertiary Consumers: Smallest energy input, highest trophic level.

Biomagnification

  • Process through which the concentration of toxins (e.g., heavy metals, pesticides) increases at each successive trophic level.
  • Examples: Mercury in fish, DDT concentration in birds of prey.

Biogeochemical Cycling

  • Essential for recycling nutrients in ecosystems.
    • Water Cycle: Involves evaporation, condensation, and precipitation.
    • Carbon Cycle: Critical for organic matter; involves carbon recycling between the atmosphere and organisms.
    • Nitrogen Cycle: Nitrogen fixation needed for organism's utilization; involves conversion of nitrogen gas to ammonia/nitrate.
    • Phosphorus Cycle: Important for energy storage (ATP); phosphorus must be available in soil for plant growth.

Survivorship Curves

  • Graphs showing survival rates across various ages, indicating reproductive strategies:
    • Type I: High survival in early and middle life, lower in older age (e.g., humans).
    • Type II: Uniform survival rate (e.g., birds).
    • Type III: High mortality in early stages but high survival once maturity is reached (e.g., fish).

Population Dynamics

  • Population Growth Factors:
    • Immigration & Births: Increase population.
    • Emigration & Deaths: Decrease population.

Exponential vs. Logistic Growth

  • Exponential Growth: Rapid increase in population when resources are abundant.
  • Logistic Growth: Population growth slows as it approaches the environment's carrying capacity (K).

Competition and Symbiotic Relationships

  • Competition: Two organisms compete for the same resources.
    • Intraspecific: Competition within the same species.
    • Interspecific: Competition between different species.
  • Symbiosis: Close ecological relationship; three types:
    • Mutualism: Both benefit.
    • Commensalism: One benefits, neither is harmed.
    • Parasitism: One benefits at the expense of the other.

Pollution and Its Effects

  • Types of Pollution: Air, water, and soil pollutants negatively impacting ecosystems.
  • Human Impact: Industrial activities, waste disposal, and others contribute to environmental degradation.

Biodiversity Crisis**

  • Threats to Biodiversity (HIPPOC):
    • H: Habitat loss
    • I: Invasive species
    • P: Population growth
    • P: Pollution
    • O: Overexploitation
    • C: Climate change
  • Efforts for preservation include conservation biology, sustainable development, and restoration projects.