Introduction to Ecology

Introduction to Ecology

• Coined in 1866 by German biologist Ernst Haeckel from Greek words "Oikos" (home) and "Logos" (study).
• Defined as the study of relationships between organisms in their natural habitats and their interactions with surroundings.

Types of Ecology

• Autecology: Focuses on single species/organisms.
• Synecology: Studies groups of multiple species.

Ecosystem Definition

• Introduced by British ecologist Arthur Tansley in 1935.
• The basic structural and functional unit of ecology, comprising biotic communities interacting with a non-living environment.
• Examples include grassland, forest, and aquatic ecosystems.

Classification of Ecosystems

• Natural Ecosystems:
  • Aquatic: Freshwater (running and standing), marine.
  • Terrestrial: Grassland, forest, desert.
• Artificial/Engineered Ecosystems: Created or modified by human activities.

Components of an Ecosystem

• Biotic Components:

  • Producers: Photo-autotrophs and chemo-autotrophs (e.g., Nitrosomonas, iron bacteria).
  • Consumers: Herbivores, carnivores, omnivores, and detritivores.
  • Decomposers: Organisms that break down organic matter.

• Abiotic Components:

  • Physical: Climate (sunlight, temperature, humidity, rainfall, wind), soil characteristics (type, moisture, pH), geographic conditions (latitude, longitude, altitude).
  • Chemical: Nutrients (macro/micro), trace elements, pollutants.

Functional Components of Ecosystems

• Food Chain: Linkage of organisms for food energy transfer.

  • Grazing Food Chain: Energy starts with plants.
  • Detritus Food Chain: Energy starts with decomposed organic matter.

• Food Web: Interconnected food chains demonstrating energy flow.

• Trophic Levels: Steps in a food chain where food/energy transfer occurs.

Importance of Food Chains and Webs

• Energy flow and transfer between organisms.
• Regulation of nutrient cycles.
• Maintenance of ecological balance and population sizes.

Ecological Pyramids

• Visual representation of energy and biomass distribution across trophic levels.

• Base of the pyramid consists of producers; successively higher levels contain consumers.

• Types of Ecological Pyramids:

  • Pyramid of Numbers: Represents population numbers at each trophic level.
  • Pyramid of Biomass: Depicts weight of organisms rather than number.
  • Pyramid of Energy: Illustrates energy flow; typically upright in shape.

Energy Flow in the Environment

• Unidirectional energy flow from producers to higher trophic levels; energy diminishes with each transfer.