Ecology | General Awareness for SSC CGL PDF Download

Introduction

The term "ecology" derives from the Greek words 'oikos,' meaning habitation, and 'logos,' meaning study. Defined by Ernst Haeckel in 1866, ecology is the scientific discipline that examines the interactions between organisms and their environments. This includes both the interactions among organisms themselves and their relationships with abiotic components of their environment. As an interdisciplinary field, ecology integrates principles from biology and Earth science.

Key Terms in Ecology

• Abiotic Factors: Non-living elements of the environment, such as temperature, water, light, and soil.
• Adaptation: The process by which organisms become familiar with their environment.
• Aestivation: A form of prolonged dormancy in response to high temperatures and dry conditions, observed in organisms like snails and fishes.
• Amensalism: A relationship where one organism negatively impacts another, with one species experiencing harm (−) and the other unaffected (0). For example, the black walnut tree secretes chemicals that inhibit nearby plants.
• Biodiversity: A term introduced by Edward Wilson to describe the variety of life forms within a specific area.
• Biotic Factors: All living organisms in an environment that influence the life of an individual organism.
• Birth Rate: The rate at which new individuals are born into a population.
• Commensalism: A relationship where one organism benefits without affecting the other; for instance, barnacles on a whale benefit from the whale's movement without harming it.
• Competition: The struggle between living organisms for limited resources like food, space, and shelter, where both parties may be negatively affected (−) and (−).
• Consumer: Organisms that rely on producers for their food, categorized into:
  • Primary Consumers: Feed on autotrophs.
  • Secondary Consumers: Feed on primary consumers.
• Death Rate: The rate at which individuals in a population die.
• Decomposition: The process of breaking down organic molecules into inorganic ones like CO2 and water, carried out by decomposers.
• Decomposer: Organisms, such as bacteria and fungi, that break down dead or decaying matter.
• Ecological Succession: The gradual change in species composition in a given area over time. For example, after a fire in a grassland, lichens initially colonize, followed by grasses, which then impact the ability of shrubs to establish.
• Ecological Productivity: The rate at which biomass is generated in an ecosystem, with varying productivity levels across ecosystems, e.g., mangroves (2500), grasslands (500), lakes (500), and open oceans (125).
• Environment: The surrounding factors influencing an organism under study.
• Emigration: The movement of individuals out of a habitat.
• Ecosystem: A functional unit of nature where living organisms interact with each other and their environment.
• Food Web: A complex network of interconnected food chains depicting the feeding relationships in an ecological community.
• Food Chain: A linear sequence of organisms where each is eaten by the next; for example:
  • Terrestrial Food Chain: Plants → Grasshopper (Primary Consumer) → Frog (Secondary Consumer) → Bird (Tertiary Consumer)
  • Aquatic Food Chain: Phytoplankton (Producer) → Zooplankton (Primary Consumer) → Small Fish (Secondary Consumer) → Big Fish (Tertiary Consumer)
• Gross Primary Productivity: The total rate at which producers convert solar energy into organic matter through photosynthesis.
• Hibernation: A state of inactivity in response to cold temperatures, characterized by reduced body temperature and metabolic functions, seen in animals like bears and bats.
• Immigration: The arrival of individuals into a habitat.
• Mutualism: A relationship where both organisms benefit without harming each other, e.g., lichens (fungus and algae) and mycorrhizae (fungi and plant roots).
• Symbiosis: The interaction between two organisms, which may be beneficial or neutral for one or both.
• Mortality: The number of deaths in a population over a given period.
• Niche: The role and space an organism occupies within its community.
• Nutrient Cycling: The movement of nutrient elements through various ecosystem components.
• Net Primary Productivity: The rate of production of organic matter by producers minus respiration losses.
• Natality: The rate of births in a population over a given period.
• Organism: A living being.
• Population Interaction: The interactions between members of the same or different species, which may be beneficial (+) or harmful (−) to one or both.
• Population: A group of organisms of the same species living in a particular area.
• Population Type: Categories of population trends, including expanding (increasing), stable, and declining (decreasing).
• Population Density: The number of individuals per unit area.
• Population Growth: The increase in the size of a population.
• Primary Productivity: The amount of biomass produced per unit area over time.
• Predation: A relationship where one organism (predator) hunts another (prey), with the predator benefiting (+) and the prey being harmed (−).
• Pollution: Any undesirable change in the physical, chemical, or biological characteristics of air, land, water, or soil.
• Producer: An autotrophic organism that synthesizes complex compounds from simple substances in its environment.
• Standing Crop: The biomass or number of living organisms in a unit area at a given time.
• Secondary Productivity: The rate at which new organic matter is produced by consumers that depend on producers.
• Sex Ratio: The comparative percentage of males to females in a population.
• Species: A group of organisms capable of interbreeding.
• Trophic Levels: The position of an organism in a food chain.