week 4

Branches of Ecology

• Ecology is the study of the relationships between organisms and their environment.
• Several branches focus on various aspects of these relationships:
  • Population ecology: Studies the dynamics of populations of a single species, including factors influencing their size, distribution, and growth.
  • Community ecology: Investigates the interactions between different species within a given area.
  • Ecosystem ecology: Focuses on the flow of energy and nutrients between organisms and their environment within an ecosystem.
  • Landscape ecology: Examines the spatial patterns and processes across multiple ecosystems.
  • Global ecology: Investigates the interactions between organisms and their environment on a global scale.

Biotic Factors

• Biotic factors are living components of an ecosystem.
• They include:
  • Producers (autotrophs): Organisms that produce their own food, typically through photosynthesis (plants, algae).
  • Consumers (heterotrophs): Organisms that consume other organisms for energy:
    • Herbivores: Animals that eat plants.
    • Carnivores: Animals that eat other animals.
    • Omnivores: Animals that eat both plants and animals.
    • Detritivores: Organisms that feed on dead organic matter.
    • Decomposers: Organisms that break down dead organic matter into simpler substances.
• These factors interact in complex food webs and trophic levels.

Abiotic Factors

• Abiotic factors are non-living components of an ecosystem.
• They include:
  • Sunlight: Provides energy for photosynthesis.
  • Temperature: Affects the metabolic rate of organisms.
  • Water: Essential for life.
  • Nutrients: Essential for growth and development.
  • Soil: Provides nutrients and support for plants.
  • Wind: Can affect plant growth and seed dispersal.
  • pH: Impacts the survival and growth of organisms.
  • Salinity: Affects aquatic organisms.
• Abiotic factors significantly influence the distribution and abundance of species.

Ecological Concepts

• Carrying capacity: The maximum population size that an environment can sustainably support.
• Competition: The struggle between organisms for limited resources.
• Predation: The interaction where one organism kills and eats another.
• Symbiosis: Close interactions between different species:
  • Mutualism: Both species benefit.
  • Commensalism: One species benefits, and the other is neither harmed nor helped.
  • Parasitism: One species benefits, and the other is harmed.
• Succession: The gradual change in species composition of a community over time.
• Biodiversity: The variety of life in a particular habitat or ecosystem.
• Ecological niche: The role of a species within its ecosystem, including its interactions with other species and resources.

Energy Flow

• Energy flows through ecosystems in one direction, starting with producers and moving through consumers and eventually to decomposers.
• The transfer of energy is inefficient, with a significant portion lost as heat at each trophic level.
• This creates a pyramid-like structure of energy transfer. Higher trophic levels have less available energy than lower levels.

Nutrient Cycling

• Nutrients are essential for life and are recycled within ecosystems.
• Elements like carbon, nitrogen, and phosphorus move through different parts of the environment (atmosphere, organisms, soil and water).
• Nutrient cycles are crucial for the maintenance of ecosystem health.

Population Dynamics

• Factors influencing population growth, including:
  • Birth rate: Number of births per unit time.
  • Death rate: Number of deaths per unit time.
  • Immigration: Movement of individuals into a population.
  • Emigration: Movement of individuals out of a population.
• These factors can lead to population growth, decline, or stability.
  • Exponential growth: Occurs when a population increases at a constant rate.
  • Logistic growth: Occurs when a population growth is limited by resources, reaching a carrying capacity.

Ecosystems

• Ecosystems are complex interactions between biotic and abiotic factors.
• Ecosystems are characterized by their unique species composition and interactions, demonstrating stability and resilience to environmental changes.
• Factors that affect and influence stability include climate, the availability of resources, and the presence and abundance of various species.

Human Impact

• Human activities significantly impact ecosystems, leading to issues like habitat destruction, pollution, and climate change.