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B4.1 Adaptation to Environment & B4.2 Ecological Niches — Comprehensive Study Notes

B4.1 Adaptation to Environment

  • Focus: how organisms adapt to their environments, how habitats and biomes shape life, and how evolution produces small genetic changes that improve survivability in a given habitat.
  • Ecosystems: organisms live in interdependent communities; interactions can be simple (nutrition transfer) or complex (multiple interspecies dependencies).
  • Key concepts: habitat, biomes, convergent evolution, and the idea that habitats and their abiotic (non-living) factors drive the range of adaptations seen in organisms.

B4.1 Habitats and Ecosystems

  • Habitats described by geography/physical location and by ecosystem type.
  • Example: Everglades description beyond GPS location (shallow water, sawgrass, alligators, birds) provides useful context about the ecosystem, not just coordinates.
  • Living organisms do not exist in isolation; each organism impacts others within the same habitat.

B4.1.1 Habitat

  • Definition: habitat is the place where a community, species, population or organism lives.
  • A habitat can host multiple species if their requirements are similar; it supports basic needs: shelter, food, water, oxygen, light.
  • A habitat may be a single species’ space or a community’s space depending on overlapping needs.
  • Key point: describe habitat by both geographical location and ecosystem type, not only by coordinates.

B4.1.2 Adaptation to abiotic environment

  • Abiotic adaptations allow organisms to cope with non-living environmental factors (e.g., sand, salt, water availability, temperature).
  • Sand dune examples:
    • Sea oats (Uniola paniculata) live on sea dunes and help build dunes; seeds stay above sand due to growth as sand accumulates.
    • Sea oats are drought-resistant with a large shallow root system and narrow leaves to reduce transpiration; stomata close when roots experience extended dry conditions.
    • Dense interwoven roots maximize water uptake after rain and help stabilize sand to reduce erosion.
    • Reproduction: produce nodes and rhizomes near base; asexual shoots rise above sand; seeds form seed heads resembling oats.
  • Mangrove adaptation (Red mangrove, Rhizophora mangle):
    • Prop roots extend above water to absorb air and oxygenate root tissues below mud.
    • Roots below water filter salt, enabling access to fresh water.
    • Adapted to tidal water level changes; tangled roots provide nursery habitat for marine life.
    • Mangroves are legally protected in many areas due to their ecological importance.
  • Shared theme: sea oats and mangroves exemplify how plants adapt to harsh, salty, water-logged, or shifting sand environments.
  • Propagule concept: red mangrove produces a propagule that germinates while attached to the parent and then drops to float in water to establish away from the parent.

B4.1.3 Abiotic variables

  • Abiotic factors are non-living components that influence species distribution and tolerance ranges.
  • Common abiotic factors include:
    • Water availability
    • Temperature range
    • Light intensity and duration
    • Soil composition
    • pH range
    • Salinity
  • Organisms have a range of tolerance for each abiotic factor; a factor outside the tolerance can limit distribution.
  • The concept of tolerance: organisms do not require constants, but acceptable ranges.
  • Figure concept: population size vs environmental gradient shows zones of optimum, stress, and intolerance.
  • Examples of organisms with wide tolerance or unusual tolerance broadening their niches:
    • Red mangroves: high salinity shorelines
    • Sea oats: sandy soils
    • Polar bears: low air temperatures
    • Thermophilic bacteria: high-temperature water sources (60–80°C)
  • Consequence: wide tolerance can reduce competition in a habitat (e.g., mangroves on saltwater shores).

B4.1.4 Limiting factors

  • Limiting factor: abiotic or biotic factor that constrains population size or presence in a habitat.
  • Concept: a factor may not be at its optimum before a species is excluded; many factors influence distribution together.
  • Skills/Applications: design transect studies to correlate abiotic factors with species distribution; collect population data and abiotic measurements along transects.
  • Transects/types:
    • Line transect: determine presence/absence at intervals
    • Belt transect: use a quadrat system along the transect to count individuals within defined areas
  • Preparatory steps for a transect study:
    • Choose abiotic factor to measure (preferably variable along transect)
    • Choose organism to count
    • Decide transect location and length, intervals, and transect type (belt width for belt transect)
  • Practical guidance: semi-natural habitats may be used; measure abiotic factor at intervals and correlate with abundance to identify limiting factors.
  • Measurements and data collection can be aided by sensors and data loggers for factors such as light, temperature, pH, CO2, etc.
  • Emphasis on replicable data collection and analysis to determine limiting factors.

B4.1.5 Coral reef formation

  • Coral reefs illustrate a marine ecosystem shaped by abiotic conditions.
  • Key mutualism: corals and zooxanthellae (symbiotic algae) require suitable conditions; their success is sensitive to abiotic factors.
  • Abiotic factors and their limiting effects on reef growth:
    • Water depth: light penetration limits where photosynthetic zooxanthellae can function; light only penetrates shallow depths; most of the ocean floor is too deep for sufficient light.
    • Water temperature: corals tolerate a narrow range, roughly between 20^{\u00b0}C and 28^{\u00b0}C; warming leads to stress and coral bleaching as zooxanthellae are expelled.
    • Salinity: coral survival depends on correct salinity; freshwater runoff can reduce salinity.
    • Water clarity: sediment or pollution reduces light passage, affecting zooxanthellae light exposure.
    • Water pH: increased CO2 lowers ocean pH (ocean acidification), reducing available calcium carbonate for reef building.
  • Human impact: rising atmospheric CO2 (ppm) is linked to lower ocean pH and coral stress; the combination of factors threatens reef health.
  • Figure-based data: long-term CO2 vs ocean pCO2 and pH data illustrate the inverse relationship between atmospheric CO2 and ocean pH.
  • Guiding questions (conceptual):
    1) Apparent correlation between atmospheric CO2 and ocean pCO2 around Hawaii?
    2) Why monitor CO2 at a mountain top long-term station?
    3) Why consistent yearly CO2 cycles?
    4) Does this prove causation between atmospheric CO2 and ocean pH?
    5) One issue with oceans as CO2 sinks? (e.g., acidification effects on calcifying organisms)

B4.1.6 Terrestrial biomes

  • Biome definition: a large geographical area with communities of plants and animals adapted to that environment; named after dominant vegetation.
  • Biomes are defined by predictable mean annual precipitation and mean annual temperature; identical temperature/rainfall patterns yield one likely biome.
  • Biome map concept: biomes can appear in multiple locations; they are not constrained by geographic borders.
  • Overlap: environmental conditions can lead to biome overlaps, and the same biome type can occur in different places.
  • Examples of biomes (as contextualized by axis plots):
    • Taiga (boreal/coniferous forest)
    • Temperate forest
    • Tropical forest
    • Grassland
    • Desert
    • Tundra
  • Illustration: climate-based biome diagram (precipitation on one axis, temperature on the other) shows how global biomes are distributed.
  • Convergent evolution across biomes: species within similar abiotic conditions may evolve similar adaptations independently, leading to similar solutions to environmental problems.
  • Example: Carnivorous plants (e.g., sundews, Nepenthes) in nutrient-poor soils have convergent solutions to nitrogen limitation via digestion of insects.
  • Important concept: convergent evolution explains similarity of adaptations across biomes despite distant relatedness; similar abiotic pressures drive similar functional outcomes.

B4.1.7 Biomes, ecosystems and communities

  • Distinction:
    • Biome: large-scale geographic unit characterized by climate and dominant vegetation.
    • Ecosystem: the physical environment plus its living organisms and their interactions.
    • Community: all living populations within an ecosystem.
  • Key note: even within the same biome, organisms from different regions may be genetically different yet share analogous morphologies and physiologies due to convergent evolution.

B4.1.8 Hot deserts and tropical rainforests

  • Desert adaptations (example: Saguaro cactus, Carnegiea gigantea):
    • Water gathering/retention: thick waxy skin, waterproof; spines for protection; long taproot and extensive shallow root system to quickly absorb sporadic rainfall; water storage in tissues; extremely slow growth (e.g., ~2 cm height at 10 years; full height ~14 m at ~200 years).
  • Kapok tree (Ceiba pentandra) in tropical rainforest: buttress roots provide a strong foundation in shallow rainforest soils, enabling rapid vertical growth to reach the canopy.
  • Epiphytes (e.g., orchids) grow on trees to access light; roots do not require soil; adapted to minimal water; examples include the orchid plants commonly sold; epiphyte mode maximizes light access.
  • Hemiepiphytes and strangler figs: begin life on a host tree with roots in the soil later; eventually encircle host tree and can kill it by competition.
  • Poison-dart frogs: brightly colored to warn predators (aposematism) and capable of producing potent toxins; many rainforest species depend on toxins derived from their diet; predators may avoid them due to warning coloration.
  • Predators and prey in deserts/rainforests: a variety of adaptations including nocturnality (fennec fox) to avoid heat stress and conserve water; special kidney adaptations in some desert mammals; camouflage and other physical/behavioral strategies.
  • Practical takeaway: hot deserts and tropical rainforests illustrate extreme ends of the abiotic factor spectrum and show how organisms adapt through a combination of structural, physiological, and behavioral traits.

B4.1.9 Guiding questions and nature of science (NOS) revisited

  • Guiding questions recap:
    • How are adaptations and habitats related?
    • Why do ecosystems within terrestrial biomes share similarities?
  • Key ideas: habitats provide abiotic challenges; organisms occupy niches through adaptations that extend their tolerance ranges; convergent evolution explains similarity of solutions across biomes.
  • NOS perspective: knowledge is tentative and evolves as new evidence arises; convergence or similarity in traits does not always indicate close relatedness; molecular data can refine understanding of relatedness and timeline of divergence.
  • Examples: carnivorous plants, kapok buttress roots, saguaro water storage strategies, and dentition vs. diet debates all illustrate how evidence can support or challenge theories about adaptation and niche occupancy.

B4.1.10 Summary of convergent evolution and biome-level similarities

  • Convergent evolution drives similar adaptations in different lineages facing similar environmental problems.
  • Biomes may host diverse communities that share functional traits due to similar abiotic constraints, even if taxa are not closely related.
  • Practical implication: when comparing distant ecosystems, expect similar functional solutions even where species differ genetically.

B4.2 Ecological Niches

  • Focus: niche as the role of a species in an ecosystem, including its space, feeding activities, and interactions with others; the niche is the “habitat plus occupation.”
  • Distinctions:
    • Spatial habitat: the physical space an organism occupies (abiotic and biotic factors such as sand, water, sunlight, soil, temperature).
    • Biotic interactions: feeding relationships, shelter, parasites, competition, predation, and mutualisms.
  • Interdependence: changes to abiotic or biotic factors can ripple through the ecosystem affecting growth, survival, and reproduction.

B4.2.1 Species and ecosystems (Ecological niche)

  • Each species has a unique niche; the niche defines how it obtains resources (e.g., food), where it lives, and how it interacts with other organisms.
  • Example: Rana pipiens (leopard frog) in dune ponds of Indiana, USA; niche includes mud in the edges of ponds, with abiotic components (sand, water, sunlight, temperature).
  • Niche concept integrates both abiotic and biotic conditions that influence performance and survival.

B4.2.2 Obligate anaerobes, facultative anaerobes and obligate aerobes

  • Tolerance concept: organisms vary in their tolerance to oxygen; some require oxygen, some cannot tolerate it, and some can switch modes depending on availability.
  • Obligate aerobes: require oxygen; cannot function without it; example: many fish species; need dissolved oxygen levels typically within a healthy range (e.g., trout thrive between roughly 7 ext{ mg L}^{-1} and 12 ext{ mg L}^{-1}; risk of death if below 3 ext{ mg L}^{-1}).
  • Obligate anaerobes: poisoned by oxygen; cannot survive in its presence; occupy anoxic or hypoxic niches (soil, deep water, animal intestines).
  • Facultative anaerobes: can perform both aerobic and anaerobic respiration depending on oxygen availability; example: Baker's yeast, Saccharomyces cerevisiae; switch to anaerobic respiration when O2 is limiting.
  • Practical example: sudden warming of water can lower dissolved oxygen, harming aerobic organisms; such events illustrate how changing abiotic factors impact tolerance and survival.

B4.2.3 Photosynthesis

  • Evolution of photosynthesis: began ~a thousand million years after life evolved; cyanobacteria were among early photosynthesizers.
  • Importance: photosynthesis is the basis for energy flow in most ecosystems; producers (autotrophs) supply energy for consumers.
  • Chlorophyll-based photosynthesis in algae and plants; chlorophyll gives leaves their green color.
  • Autotrophs produce food from inorganic substances using light energy; they are producers and form the foundation of most ecosystems.
  • Notable historical note: 1815 volcanic dust caused global cooling, reducing solar energy and thus reducing photosynthesis, leading to crop failures in some areas.

B4.2.4 Holozoic nutrition

  • Holozoic nutrition refers to ingesting, digesting, absorbing, and assimilating nutrients from other organisms; animals are heterotrophs and are consumers.
  • Distinctions: autotrophs produce their own food via photosynthesis; heterotrophs obtain food by consuming others.
  • Examples of heterotrophs: zooplankton, sheep, fish, birds.

B4.2.5 Mixotrophic nutrition

  • Mixotrophy: organisms can be both autotrophic and heterotrophic; some protists (e.g., Euglena) exhibit this; mixotrophy can be obligate (must use both modes) or facultative (can use either mode depending on conditions).
  • Significance: useful in environments with fluctuating light or prey availability; allows flexibility in nutrient acquisition.

B4.2.6 Saprotrophic nutrition

  • Saprotrophs decompose dead organic matter by secreting digestive enzymes and absorbing digestion products; key decomposers include fungi and bacteria.
  • Role: recycling nutrients; breakdown of dead material (e.g., a mushroom on a fallen trunk).
  • Concept: bioremediation uses microbes to detoxify polluted environments; some archaea can process extreme conditions to transform toxins.

B4.2.7 Diversity of nutrition in archaea

  • Archaea are one of three domains (Bacteria, Archaea, Eukarya) and display diverse metabolism.
  • Energy and carbon acquisition strategies include:
    • Photosynthesis (with pigments like bacteriorhodopsin in Haloarchaea)
    • Chemosynthesis (oxidation of inorganic compounds, e.g., Ferroplasma acidiphilum oxidizes ferrous iron in acidic environments)
    • Heterotrophic nutrition (eating organic compounds)
  • Special notes:
    • Some archaea rely on ammonia (NH3) in oceans/soils to enable nitrogen cycling.
    • Haloarchaea thrive in very salty environments (great salt lakes, Dead Sea).
    • Holozoic vs. saprotrophic definitions apply similarly to archaea in contexts of energy acquisition.

B4.2.8 The relationship between dentition and diet (Hominidae)

  • Overview: comparing dentition to diet uses vertebrate skulls and teeth morphology to infer dietary habits.
  • Ancestral and extant genera in Hominidae: Pongo (orangutans), Gorilla (gorillas), Pan (chimpanzees), Homo (humans).
  • Fossil evidence includes bones, skulls, teeth, and sometimes tools or DNA; context from archaeology is important for robust conclusions.
  • Tooth anatomy and typical diets:
    • Incisors: front teeth for cutting; larger in folivores/fruit eaters; used as scissors with apples/sandwiches in humans or leaves in folivores.
    • Canines: tearing; pointed; longer in some omnivores; large in some primates for display/competition.
    • Premolars and molars: for crushing and grinding; width and shape relate to diet (carnivores have sharp, serrated premolars/molars; herbivores have broad, rounded molars).
  • Diets of great apes:
    • Orangutans: mostly fruit; some leaves; occasionally insects; largely frugivores.
    • Gorillas: primarily plant material; folivores; rare insects; occasionally meat but mostly herbivores.
    • Chimpanzees: omnivores; fruit predominant but also leaves, stems, invertebrates, and vertebrates.
    • Humans: omnivores; diet includes fruit, grains, vertebrates; dentition reflects a mix of omnivorous feeding with reduced reliance on carnivorous teeth.
  • Connecting dentition with diet:
    • Herbivores: large incisors; broad, flat grinding molars; strong grinding dentition.
    • Carnivores: sharp, pointed canines; serrated and narrow premolars/molars for tearing.
    • Omnivores: intermediate dentition; mixed features.
  • Case analyses:
    • Chimpanzees show dentition with small incisors and notable canines for meat eating; however, humans have less pronounced carnivore teeth yet historically ate meat, aided by tools and fire.
    • Orangutans have long canines but do not primarily consume meat; dental morphology does not always map directly to diet due to another uses (e.g., display, tool use).
  • Microwear as evidence: microscopic tooth wear patterns reveal the type of food eaten (softer vs. harder foods, grit from soil).
  • Nature of science (NOS) perspective:
    • Observations of living mammals underpin theories linking dentition to diet; however, diversity and exceptions exist; theories must adapt with new evidence.
    • Teeth can serve defensive roles, not just feeding; cooking meat reduces need for specialized carnivore dentition.
  • Visuals: skull images (gorilla, chimpanzee, human) and dentition diagrams illustrate the various tooth types and configurations.

B4.2.9 Adaptations of herbivores and plants (plant–herbivore interactions)

  • Herbivory challenges plants: cellulose and lignin are hard to digest; specialized mouthparts (piercing/sucking by aphids; chewing by grasshoppers/caterpillars) facilitate feeding.
  • Vertebrate herbivores (e.g., cows, sheep) use broad grinding teeth; ruminant systems involve regurgitation and rechewing (cud) aided by gut microbes that digest cellulose.
  • Plant defenses: physical barriers (thorns, thick bark, shells), chemical deterrents (secondary compounds like alkaloids, tannins, phytotoxins).
  • Examples of plant toxins and uses:
    • Foxgloves (Digitalis) produce cardiac-active toxins used medicinally.
    • Castor bean (Ricinus communis) seeds contain ricin; oil is processed to remove toxin.
    • Secondary compounds deter herbivory; some animals detoxify toxins via gut microbes (particularly ruminants).
  • Herbivore counter-adaptations:
    • Microbial detoxification in the gut (for certain toxins).
    • Cautious sampling in unfamiliar plants to limit toxin intake.
    • Salivary proteins in some herbivores neutralize tannins.
  • Examples of plant–herbivore interactions:
    • Nettle (Urtica dioica) uses silica hairs and irritants to deter herbivory.
    • Phytotoxins in certain plants require detoxification pathways in herbivores.
  • Broader note: secondary compounds can be used by humans for medicines (e.g., quinine, penicillin, caffeine).
  • Epilogue: adaptive arms race between plants and herbivores shapes coevolutionary dynamics.

B4.2.10 Adaptations of predators and prey

  • Predators: rely on chemical, physical, and behavioural adaptations to find, catch, and kill prey.
  • Chemical strategies: venoms (e.g., black mamba) paralyze prey; pheromones and lure-based predation (e.g., spiders using pheromone tricks) can trap prey.
  • Physical strategies: speed, claws, teeth, and digestive systems adapted for efficiency and risk management; brains that evaluate risk and energy expenditure.
  • Behavioural strategies: pack hunting (wolves), cooperative strategies, and social structures that enhance success; some insects (ants/termite/bee wasps) use cooperative behaviors like warfare or raiding parties.
  • Ambush predators: rely on surprise; examples include anglerfish that use a lure (illicium) to attract prey instantly engulfing them.
  • Pursuit predators: rely on speed or endurance; persistence hunting used by humans and some predators.
  • Prey adaptations:
    • Chemical deterrents (poisons) and bright coloration (aposematism) to warn predators; predators may avoid toxic prey.
    • Camouflage and mimicry (aposematic coloration, Mullerian/Maierian mimicry) help prey avoid detection.
    • Group living (safety in numbers) reduces individual predation risk; elephants, wildebeest, and other herds benefit from collective vigilance.
  • Examples of toxins and warning signals: poison-dart frogs produce toxins; bright coloration signals danger to predators; some non-venomous species mimic dangerous signals to deter predation (mimicry).
  • Physical defense: exoskeletons (invertebrates), shells (turtles, mollusks), spines (porcupines).
  • Behavioural defenses: flight, hiding, alarm calls, and social coordination to deter predators.
  • Takeaway: predator–prey interactions are a driver of ecological and evolutionary dynamics, shaping niche occupation and community structure.

B4.2.11 Harvesting light

  • Plant strategies to maximize light capture in forest ecosystems:
    • Leaves are flat and angled to maximize light interception; chloroplasts concentrated on the upper leaf surface for efficient light capture.
  • Tree-level strategies:
    • Canopy height: trees grow tall to reach light; canopies compete for sunlight; tall trees invest heavily in sturdy trunks and branches.
    • Lianas (vines): climb from forest floor to canopy by using trees as scaffolds; seedlings grow toward shade and then climb, competing with host trees for light and nutrients.
    • Epiphytes (e.g., orchids): grow on tree trunks and branches; roots absorb moisture from rain and humidity; not rooted in soil; can reach canopy with minimal soil contact.
    • Strangler figs (hemiepiphytes): start life high on a host tree, then send roots to ground to anchor and strangle the host, eventually replacing it.
  • Shade-tolerant understory plants: adapted to low light and diffuse sunlight; examples include understory shrubs and herbs; bananas and ginger as understory herb examples; adaptations to low light include efficient light capture and slower growth rates.
  • Concept: different life-forms in forests cooperate to harvest light efficiently at various vertical strata.

B4.2.12 Fundamental and realized niches

  • Fundamental niche: the potential niche a species could occupy given its adaptations and tolerance limits.
  • Realized niche: the actual niche a species occupies given competition and interactions with other species.
  • Example: red fox (Vulpes vulpes) in the USA: fundamental niche includes forest edge with a diet of small mammals, amphibians, and insects; realized niche narrowed by conversion to farmland and competition with coyotes (Canis latrans).
  • Implication: competition often reduces the realized niche relative to the fundamental niche; niche differences can be exploited by resource partitioning and adaptive responses.

B4.2.13 Competitive exclusion

  • Principle: no two species can occupy exactly the same niche indefinitely; complete niche overlap leads to competitive exclusion.
  • Classic demonstration: Gause’s Paramecium aurelia vs. Paramecium caudatum experiments (1934): when grown separately, both thrived; when grown together with constant food, P. caudatum died out while P. aurelia survived, illustrating competitive exclusion.
  • Practical notes:
    • In nature, niche overlap may lead to competitive exclusion over time; observed coexistence may be due to niche differentiation or temporal/spatial separation.
    • Examples in human-impacted ecosystems show introduced species displacing natives (e.g., eastern gray squirrels vs red squirrels in Britain) via competition, disease, or habitat alteration.
  • Important caveat: competitive exclusion is one mechanism among many that shape community structure; other factors (predation pressure, environmental changes, mutualisms) also influence outcomes.

Nature of Science (NOS) and Integration Across Topics

  • NOS perspective threads appear throughout: theories are constructed from observations of living organisms and are refined as new evidence emerges.
  • The dentition–diet section emphasizes that there are exceptions and complexities; morphology can serve multiple roles (defense, display) beyond feeding, and tools/cooking can alter dietary inferences.
  • The coral reef and biome sections illustrate how data (e.g., CO2 levels, pH, temperature) are interpreted with respect to hypotheses about ecosystem health and climate change; causation is complex and requires controlled, multi-factor analyses.
  • Practical implications for science education: use of transects, sensors, and data logging to quantify abiotic factors; understanding tolerance ranges and limits helps explain species distributions and resilience under changing environmental conditions.

Key Formulas and Numerical References (LaTeX)

  • Coral reef temperature tolerance range:
    • 20^{\circ}\text{C} \le T \le 28^{\circ}\text{C}
  • Dissolved oxygen thresholds (example for trout):
    • Healthy range: roughly 7 \text{ mg L}^{-1} \le DO \le 12 \text{ mg L}^{-1}
    • Hypoxia risk below: DO < 3 \text{ mg L}^{-1}
  • Atmospheric CO2 and ocean chemistry data references:
    • Atmospheric CO2 increases (ppm) correspond to lower ocean pH due to increased dissolution of CO2 forming carbonic acid; explicit numbers vary over time and locations (e.g., Hawaiian monitoring data show rising CO2 ppm and corresponding changes in ocean pCO2 and pH over years).
  • Featural measurements and ranges (examples cited in text):
    • Water depth and light penetration limits to coral growth; temperature range; salinity constraints; clarity and pollution impacts on light transmission; carbonate chemistry affected by CO2 levels and pH.

Connections to Foundational Principles and Real-World Relevance

  • Evolution and adaptation: genetic variation and natural selection drive adaptations; life-history traits adapt to abiotic gradients and biotic interactions.
  • Biomes as organizing principles: global climate (temperature and precipitation) shapes major vegetation and animal communities; convergent evolution demonstrates functional similarity across distant lineages living under similar conditions.
  • Niches and community structure: fundamental vs. realized niches explain how competition shapes species distributions; competitive exclusion highlights the consequences of niche overlap.
  • Ecosystem services and resilience: mangroves’ root networks prevent erosion and provide nursery habitats; coral reefs support high biodiversity; keystone interactions underpin ecosystem stability under environmental changes.
  • Ethical and practical implications: human activities (deforestation, climate change, ocean acidification, introduction of invasive species) alter abiotic conditions and disrupt ecological balances; understanding these processes informs conservation and resource management.

Examples and Hypothetical Scenarios (Sketches for Exam Thinking)

  • Scenario: A coastal area experiencing rising sea levels and increased salinity — predict potential shifts in mangrove density, sea oats, and associated nursery habitats; discuss how root adaptations and salt filtration contribute to resilience.
  • Scenario: A transect study across a gradient of light in a forest understory — outline data collection steps, how to measure light intensity, and how to correlate with understory plant abundance to identify a limiting factor.
  • Scenario: An introduced rodent species in a temperate region — discuss potential competitive exclusion with native species, possible niche shifts, and indicators to monitor (population trends, food resource use, habitat changes).

Quick Recap of Key Terms

  • Habitat, biome, ecosystem, niche
  • Convergent evolution, adaptive radiation
  • Holozoic vs. mixotrophic nutrition, saprotrophs
  • Obligate vs. facultative anaerobes/aerobes
  • Photosynthesis, producers, autotrophs
  • Fundamental vs. realized niche
  • Competitive exclusion
  • Aposematism, mimicry, biotic and abiotic interactions
  • Lianas, epiphytes, hemi-epiphytes, strangler figs
  • Coral-zooxanthellae mutualism
  • Coral bleaching, ocean acidification, pH dynamics
  • Transect, line vs belt transect, quadrats