Notes From Toppers

Ecology, Biodiversity and Conservation

Ecosystems

  • Structure and function of ecosystems:
    • Components: biotic (producers, consumers, decomposers) and abiotic (physical and chemical factors).
    • Energy flow: pathways of energy transfer through trophic levels, food chains, food webs.
    • Nutrient cycling: biogeochemical cycles (carbon, nitrogen, phosphorus, etc.) and their significance.

(References: NCERT Biology Class 11, Chapter 14, Chapter 15)

Biodiversity

  • Importance: ecological processes, ecosystem services, genetic resources, medicinal potential, aesthetic and cultural values.
  • Types of biodiversity:
    • Genetic diversity: variations in genes within a population.
    • Species diversity: variety of species in a region.
    • Ecosystem diversity: different ecosystems and habitats.
  • Measurement and indices: species richness, species diversity indices (Shannon-Wiener index, Simpson’s index), evenness.
  • Species-area relationship: positive correlation between species richness and area.
  • Ecological hotspots: areas with high species richness and endemism, conservation significance.

(References: NCERT Biology Class 12, Chapter 13)

Population Ecology

  • Population growth models:
    • Exponential growth: rapid increase in population size under ideal conditions.
    • Logistic growth: growth slows down as the population approaches carrying capacity.
  • Population regulation mechanisms:
    • Density-dependent factors: competition, predation, parasitism, diseases, etc.
    • Density-independent factors: natural disasters, climate changes, etc.
  • Life history strategies:
    • r-strategists: high reproductive rate, short lifespan, small body size (e.g., insects).
    • K-strategists: low reproductive rate, long lifespan, large body size (e.g., elephants).
  • Survivorship curves: graphical representations of the number of individuals surviving over time.
  • Age structure diagrams: graphical representations of the age distribution of a population.
  • Reproductive strategies: semelparity (reproduce once and die) vs. iteroparity (reproduce multiple times).

(References: NCERT Biology Class 12, Chapter 14)

Community Ecology

  • Community structure: composition and abundance of species in a community.
  • Species interactions:
    • Competition: for resources such as food, space, mates.
    • Predation: one species (predator) hunts and consumes another (prey).
    • Mutualism: beneficial relationship between two species.
    • Commensalism: one species benefits while the other is unaffected.
  • Ecological succession: sequential changes in the species composition of a community over time.
  • Pioneer species: first species to colonize a new habitat.
  • Climax community: stable, self-sustaining community that eventually develops.
  • Disturbance ecology: role of disturbances (natural and anthropogenic) in shaping communities.
  • Invasive species: non-native species that have a negative impact on the ecosystem.

(References: NCERT Biology Class 12, Chapter 15)

Ecosystem Services

  • Services provided by ecosystems:
    • Water regulation: control of water flow and quality.
    • Climate regulation: regulation of temperature and precipitation patterns.
    • Pollination: transfer of pollen from one flower to another, essential for plant reproduction.
    • Soil formation and fertility: creation and maintenance of soil, nutrient cycling.
    • Biodiversity: maintenance of genetic diversity and ecological balance.
    • Aesthetic and cultural values: recreation, spiritual significance, etc.
  • Economic valuation of ecosystem services: assigning monetary values to the benefits provided by ecosystems.

(References: NCERT Biology Class 12, Chapter 16)

Threats to Biodiversity

  • Habitat loss and fragmentation: clearance of forests, urban expansion, road construction.
  • Poaching and illegal wildlife trade: hunting and trading of endangered species for their body parts or fur.
  • Climate change: altered temperature, precipitation patterns, sea level rise, ocean acidification.
  • Pollution: release of harmful substances into the environment, air pollution, water pollution, soil pollution.
  • Invasive species: introduction of non-native species that outcompete native species for resources.
  • Overexploitation of resources: unsustainable harvesting of resources such as timber, fish, etc.

(References: NCERT Biology Class 12, Chapter 17)

Conservation:

  • Conservation Strategies:
    • In-situ conservation:
      • Protected areas: national parks, wildlife sanctuaries, biosphere reserves.
      • Community conservation: involving local communities in conservation efforts.
    • Ex-situ conservation:
      • Seed banks, gene banks, botanical gardens, zoos, aquaria.
  • Biodiversity Conservation Acts and Policies:
  • Wildlife Protection Act (1972).
  • Forest Conservation Act (1980).
  • Biodiversity Act (2002).
  • National Biodiversity Action Plan (NBAP).
  • Ramsar Convention (1971): conservation and wise use of wetlands.
  • Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES): regulates the trade of endangered species.
  • IUCN Red List: categorized species according to their extinction risk.
  • Conservation Success Stories:
  • Bengal tiger conservation efforts.
  • Asiatic lion conservation efforts.
  • Hawaiian monk seal conservation efforts.
  • Challenges in Conservation:
  • Balancing conservation with economic development.
  • Human-wildlife conflict.
  • Poaching and illegal wildlife trade.
  • Climate change.
  • Lack of political will and funding.
  • Conservation Education and Awareness:
    • Importance of education in promoting conservation.
    • Raising public awareness about biodiversity and conservation issues.
  • Sustainable Development:
    • Integrating conservation into development planning.
    • Sustainable agriculture and forestry practices.
    • Ecotourism.
    • Green technology.
    • Corporate social responsibility.

(References: NCERT Biology Class 12, Chapter 17)