CG

Ecological Relationships, Adaptation, and Biodiversity Conservation

Ecological Relationships (C4.1)

  • Population Control:

    • Density-dependent factors (competition, predation, pathogens) regulate population size via negative feedback towards carrying capacity.

  • Population Growth:

    • Initial exponential growth phases; sigmoid curve is an idealized model.

    • Data collection (e.g., yeast, duckweed) helps model sigmoid growth.

  • Intraspecific Relationships: Competition and cooperation occur within species.

  • Communities: All interacting populations (plants, animals, fungi, bacteria) in an ecosystem.

  • Interspecific Relationships: Herbivory, predation, competition, mutualism, parasitism, pathogenicity.

  • Mutualism: Both species benefit (e.g., Fabaceae root nodules, orchid mycorrhizae, coral zooxanthellae).

  • Resource Competition: Invasive species often outcompete endemic species.

  • Testing Competition: Evident if one species is more successful without another.

    • Approaches: laboratory experiments, field observations, field manipulation.

  • Chi-squared Test: Used to assess association between two species' distributions, indicating interspecific competition.

  • Predator-Prey: A density-dependent control mechanism for animal populations.

  • Population Control Types: Top-down and bottom-up control (one often dominant).

  • Chemical Deterrence: Allelopathy and antibiotic secretion inhibit competitors.

Adaptation to Environment (B4.1)

  • Habitat: Specific place where a species/population/community lives.

  • Abiotic Adaptations: Organisms adapt to non-living factors (e.g., dune grasses, mangrove trees).

  • Abiotic Variables: Climate, soil, water conditions influence species distribution; species have a range of tolerance.

  • Range of Tolerance: Species distribution correlates with abiotic variables; measurable via transect data or sensors.

  • Coral Reefs: Require specific abiotic conditions: adequate water depth, pH, salinity, clarity, temperature.

  • Biome Distribution: Terrestrial biome types determined by temperature and rainfall patterns.

  • Biomes: Large-scale ecosystems with similar communities due to similar abiotic conditions and convergent evolution (e.g., tropical forests, deserts, tundra).

  • Specific Adaptations: Organisms in biomes like hot deserts and tropical rainforests have distinct adaptations.

Conservation of Biodiversity (A4.2)

  • Biodiversity: Encompasses ecosystem, species, and genetic diversity.

  • Historical vs. Current Species: More species exist today than historically, many undiscovered.

  • Anthropogenic Extinction: Human activities cause the sixth mass extinction (e.g., moas, Caribbean monk seals).

  • Ecosystem Loss: Primarily due to anthropogenic factors (e.g., deforestation of dipterocarp forests).

  • Biodiversity Crisis Evidence: Based on reliable, repeated surveys (expert and citizen science) showing changes in species richness and evenness.

  • Crisis Causes: Human population growth, over-exploitation, urbanization, habitat loss (deforestation/agriculture), pollution, and invasive species.

  • Conservation Approaches: Multi-faceted strategy: in situ (reserves, rewilding) and ex situ (zoos, gene banks).

  • EDGE Program: Prioritizes conservation for Evolutionarily Distinct and Globally Endangered species.

Human Impact on Environment (D4.2)

  • Greenhouse Effect: Gases like carbon dioxide (CO2), methane (CH4), and water vapor naturally trap heat, maintaining Earth's temperature.

  • Enhanced Greenhouse Effect: Anthropogenic activities (e.g., burning fossil fuels, deforestation) increase greenhouse gas concentrations, leading to global warming.

  • Ocean Acidification: Increased atmospheric (CO2) dissolves in oceans, forming carbonic acid (H2CO_3), which lowers ocean pH.

    • Impacts: Threatens marine calcifiers (corals, molluscs) by reducing available carbonate ions needed for shells/skeletons.

  • Coral Bleaching: Increased ocean temperature causes corals to expel symbiotic algae (zooxanthellae), leading to coral death if prolonged.

  • Sea Level Rise: Thermal expansion of water and melting glaciers/ice sheets contribute to rising sea levels, threatening coastal areas.

Pollution and Impact (D4.3)

  • Types of Pollution: Air, water, soil, plastic, light, sound, thermal pollution.

  • Sources of Pollution: Industrial emissions, agricultural runoff, domestic waste, vehicle exhaust.

  • Eutrophication: Nutrient enrichment (e.g., nitrates and phosphates from agricultural runoff) in aquatic ecosystems.

    • Leads to algal blooms, oxygen depletion (hypoxia/anoxia), and disruption of food webs.

  • Biomagnification: Accumulation of toxins (e.g., DDT, mercury) in organisms at successive trophic levels due to food chain transfer.

    • Higher concentrations in top predators, causing reproductive and developmental issues.

  • Plastic Pollution: Non-biodegradable plastics accumulate in ecosystems.

    • Macroplastics: Physical harm (entanglement, ingestion).

    • Microplastics: Ingested by small organisms, enter food web, potential for toxin transfer.

  • Ozone Depletion: Chlorofluorocarbons (CFCs) deplete the stratospheric ozone layer $$(O