Ecology - Organisms and Populations (Diversity of Living Organisms) - Concepts to Remember for JEE and CBSE Board Exams

Key Concepts:

• Biodiversity:

  • Definition: Describes the variety of life forms present on Earth, including plants, animals, microorganisms, and their complex ecological relationships.
  • Significance: Underpins the functioning of ecosystems and provides essential services such as food, clean water, air, soil fertility, and climate regulation. Also vital for drug discovery and agriculture.

• Species:

  • Definition: A fundamental unit of classification, referring to a group of organisms that can interbreed and produce fertile offspring.
  • Uniqueness: Each species is unique and has a specific set of genetic traits, adaptations, and behaviors that distinguish it from other species.

• Ecosystem:

  • Definition: Interacting community of living organisms (biotic factors) and their non-living environment (abiotic factors) within a defined area.
  • Components: Biotic factors include producers, consumers, decomposers, while abiotic factors include physical conditions (temperature, light, water, soil) and chemical factors (nutrients, pH).

• Population:

  • Definition: A group of organisms of the same species that inhabit the same area and interact with each other.
  • Dynamics: Population size constantly changes due to several factors, including birth rate (natality), death rate (mortality), immigration (individuals entering the population), and emigration (individuals leaving the population).

• Habitat:

  • Definition: The specific environment where an organism or a species lives, providing the conditions necessary for survival and reproduction.
  • Importance: Each organism is adapted to a specific habitat, and any change in habitat conditions can affect their survival and well-being.

• Ecological Niche:

  • Definition: The full range of conditions an organism requires for survival and its role in the ecosystem, including its interactions with other organisms.
  • Significance: Understanding the ecological niche helps comprehend how species adapt and coexist within an ecosystem, leading to ecological stability.

• Inter-specific Interactions:

  • Predation: Interaction where one organism (predator) hunts and consumes another organism (prey).
  • Competition: Interaction where two or more organisms compete for limited resources like food, mates, or territory.
  • Mutualism: Beneficial relationship where both participating species gain advantages from each other’s presence.
  • Commensalism: A relationship where one species gains benefits without affecting the other, which neither benefits nor is harmed.
  • Parasitism: A relationship where one organism (parasite) benefits by harming a host organism from the same or a different species, potentially leading to disease.

• Carrying Capacity:

  • Definition: The maximum population size an environment can sustain indefinitely without degrading its resources or exceeding its ability to provide essential resources.
  • Factors Affecting Carrying Capacity: Includes resource availability (food, water, space), abiotic factors (climate, topography, natural disasters), interactions with other species, and anthropogenic factors (pollution, resource exploitation).

• Population Regulation:

  • Mechanisms:
    • Density-dependent factors: Factors whose impact on the population depends on the population size, such as competition, predation, and disease.
    • Density-independent factors: Factors that influence the population regardless of its size, such as natural disasters, extreme weather, and climate change.

• Population Ecology:

  • Age Structure: Refers to the number of individuals in different age groups within a population. Helps comprehend population dynamics and reproductive success.
  • Survivorship Curves: Graphical representations that show the probability of an individual surviving from birth to different age groups. Helps analyze the effects of mortality factors.
  • Exponential Growth: Occurs when a population size increases exponentially over time under ideal conditions (unlimited resources).
  • Logistic Growth: Occurs when population growth slows down as the carrying capacity is approached or reached, resulting in a sigmoid curve.

• Environmental Impact on Populations:

  • Climate Change: Affects species’ distributions, abundance, behavior, and interactions, potentially leading to shifts in ecosystem dynamics.
  • Habitat Loss: Conversion or degradation of natural habitats due to human activities, which jeopardizes species’ survival and disrupts ecological processes.
  • Pollution: Introduction of harmful substances into the environment, causing detrimental effects on organism health, reproduction, and ecosystem functions.