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.
- In-situ conservation:
- 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)