APES Midterm

AP Environmental Science Notes

Unit 1

Section 2- Environmental History

2.01: Historical Effects of Humans on Environment

Human Timeline and Earth’s Age

• Humans: Existed for 90,000-200,000 years.

• Earth: 4.6 billion years old.

• Early humans lived as hunter-gatherers.

Major Cultural Revolutions

• Agricultural Revolution (12,000 years ago)

  • Shift from hunter-gatherer to settled communities.

  • Domestication of plants and animals.

  • Slash-and-burn technique and fallow periods for sustainability.

• Industrial Revolution (mid-1700s)

  • Shift to non-renewable resources like coal, oil, and natural gas.

  • Growth of cities and migration from rural areas to urban centers.

  • Advancements in production, trade, and agricultural efficiency.

• Globalization/Information Revolution (current)

  • Increased knowledge and sophisticated technology.

  • Impact on the environment includes both benefits (monitoring, resource efficiency) and drawbacks (cultural homogenization, environmental degradation).

Hunter-Gatherer Societies

• Lived in small, low-impact bands.

• Knowledge of earth wisdom: survival while minimizing environmental impact.

• Limited resource depletion, but early humans affected the environment:

  • Shifted forests to grasslands.

  • Contributed to the extinction of some large species.

Agricultural Developments

• Early Agriculture: Slash-and-burn and use of cover crops helped restore soil.

• Advancements: Plow usage increased food production and led to trade, cities, and higher birth rates.

• Impact: Land clearing for farming reduced natural habitats.

Industrial Advancements

• Fossil fuel reliance grew due to wood shortages.

• Population boomed, urban migration increased, and life expectancy rose.

• Environmental impact escalated with mechanization and factory growth.

Globalization and Environmental Knowledge

• Better environmental monitoring and problem-solving abilities.

• Models and technology developed for complex system analysis.

• Downsides include environmental impact and cultural changes.

U.S. Environmental History Eras

• Tribal Era (pre-1607): Native Americans lived sustainably with respect for the land.

• Frontier Era (1607-1890): European settlers exploited resources, cleared land, and led rapid expansion.

• Homestead Act of 1862: Gave settlers land, increasing environmental alteration.

• End of Frontier (1890): The government declared the wilderness "tamed."

Key Takeaways

• Hunter-gatherers had a lower environmental impact because they allowed nature to recover (answer: D).

• Frontier Era attitudes toward environmental exploitation have influenced current practices and views on land use.

2.02

1. Four Major Eras in U.S. Environmental History

   • Tribal and Frontier Eras (1607–1890)

   • Early Conservation Era (1832–1960)

   • Environmental Era (1960–present)

   • Focus: Early Conservation Era, a time of growing environmental awareness.

2. Pioneers of Conservation

   • Henry David Thoreau (1830s): Observed biodiversity loss in Massachusetts; lived at Walden Pond, wrote Life in the Woods.

   • George Perkins Marsh (1864): Published Man and Nature, questioning resource limits and establishing conservation principles.

3. Health and Resource Management Concerns (1870–1900)

   • Rising awareness of pollution and health risks in cities.

   • Forest Reserve Act (1891): U.S. federal protection of land resources.

   • John Muir (1892): Founded Sierra Club, leading preservation efforts; promoted minimal-impact activities like hiking and camping.

4. National Park and Wilderness Legislation

   • National Park System (1916): Established protected lands for public enjoyment.

   • Wilderness Act (1964): Protected 9 million acres as legally defined wilderness, expanding over time to 109.5 million acres.

5. Theodore Roosevelt’s Conservation Achievements

   • Presidency (1901–1909): Pioneered U.S. conservation efforts, protecting 230 million acres.

   • Established Bureau of Forestry (now U.S. Forest Service), tripled forest reserves.

   • Antiquities Act (1906): Allowed presidential designation of national monuments.

6. Conservation vs. Preservation

   • Conservationists (Roosevelt, Pinchot): Supported “wise use” of resources for sustainable growth.

   • Preservationists (Muir): Advocated leaving nature untouched.

   • Hetch Hetchy Valley Dispute: Clash between conservationist and preservationist views over damming in Yosemite, leading to legal controversy.

7. Aldo Leopold and Land Ethic

   • 20th-century environmentalist advocating for a “land ethic.”

   • Promoted respect for land as a community that includes humans.

8. New Deal and Soil Conservation

   • Franklin D. Roosevelt: New Deal programs like the Civilian Conservation Corps (CCC) aimed at environmental restoration.

   • Soil Conservation Act (1935): Federal support for soil preservation efforts.

9. Influence of Rachel Carson and Environmental Movement

   • Silent Spring (1962): Exposed DDT's harmful effects, inspiring the environmental movement.

   • Wilderness Act (1964): Created the National Wilderness Preservation System, protecting land for low-impact recreation.

10. Ecology and the Spaceship Earth Perspective

    • Ecology became a recognized science (1965–1970).

    • 1969 Apollo mission photo highlighted Earth as a fragile, interconnected system.

2.03

• Time Period: Began in 1970, continues to present.

• Characteristics: Period of both positive and negative environmental policy decisions.

2. The 1970s – "The Decade of the Environment"

• Rise of Environmental Awareness: Growing interest in environmental protection and regulation.

• Key Actions:

  • EPA Creation (1970): Environmental Protection Agency established by President Nixon.

  • Key Laws:

    • Endangered Species Act (1973): Federal protection for endangered species.

    • Clean Water Act & Marine Mammal Protection Act.

    • Consumer Product Safety Act & Pesticide Control Act.

  • CFC Discovery (1974): Chemists found that chlorofluorocarbons (CFCs) deplete the ozone layer.

• Significant Events: Oregon passed the first Bottle Recycling Law (1972).

3. 1977-1981 – Jimmy Carter’s Administration

• Environmentally Conscious Leadership:

  • Created the Department of Energy to manage energy conservation.

  • Protected more land with the National Wilderness System using the Antiquities Act.

  • Superfund (CERCLA): Established to manage hazardous waste sites, inspired by the Love Canal incident.

4. The 1980s – Anti-Environmental Movement

• Ronald Reagan’s Policies:

  • Rolled back regulations on gas mileage, air pollution, and water quality.

  • Supported development on public lands, weakened environmental research funding.

• Wise Use Movement (1988):

  • Grassroots movement advocating for rural rights, opposed environmental regulations.

  • Claimed that environmental laws overlooked the rural perspective.

5. Late 1980s and Early 1990s

• President George H.W. Bush:

  • Initially supportive of environmental causes but later criticized for lack of action on issues like global warming.

• Bill Clinton (1993-2001):

  • Appointed environmental advocates to key positions.

  • Tightened logging restrictions, improved emissions standards, and protected large areas of land.

  • Criticized for not pushing strong enough global warming policies.

6. Early 2000s – George W. Bush’s Administration

• Environmental Policy Rollbacks:

  • Pulled back from the Kyoto Protocol on reducing greenhouse gas emissions.

  • Increased focus on nonrenewable resources, ignored scientific reports on climate change.

7. 2009-2017 – Barack Obama’s Administration

• Significant Environmental Actions:

  • Strict greenhouse gas emissions standards.

  • Enforced penalties for environmental disasters (e.g., BP oil spill).

  • Enrolled the US in the 2015 Paris Agreement to reduce emissions globally.

  • Limited destructive practices (e.g., fracking, mountain-top mining), promoted the green economy.

8. 2017-2021 – Donald Trump’s Administration

• Environmental Deregulation:

  • Rolled back Obama-era climate regulations, including vehicle fuel efficiency.

  • Reduced size of national monuments (e.g., Bears Ears), opposed environmental spending.

• International Perception:

  • Viewed as abandoning leadership in climate change initiatives.

  • Opposition from environmentalists; legal challenges to reduce monument protections.

Section 3- Science, Systems, Matter, and Energy

3.01

Goals and Process of Science

• Science's Aim: Discover and organize nature; use findings to make predictions.

• Scientific Process: Begins with a question, followed by data collection through observations or measurements.

• Ultimate Goal: Not just to collect facts but to bring forward new ideas that explain and predict.

Hypothesis and Theory Development

• Hypothesis: A proposed explanation based on observations; it must be both explanatory and predictive and be reproducible (can be tested repeatedly with consistent results).

• Theory: A thoroughly tested and reliable hypothesis.

• Scientific Law: Statement of observed natural phenomena that recur (e.g., First Law of Thermodynamics).

Example of the Scientific Method

• Observation: Phone is dead despite charging.

• Hypothesis Testing:

  1. Hypothesis 1: Charger might not work.

     • Test: Charge a friend’s phone; result shows the charger works.

  2. Hypothesis 2: Phone battery may no longer hold a charge.

     • Test: Replace battery, charge phone again; phone charges successfully.

Controlled Experiments and Variables

• Controlled Experiment: Isolates a single variable for testing (e.g., comparing a dead phone to a friend’s functional phone).

• Environmental Science: Often includes multiple variables (synergism) requiring mathematical models to account for complex interactions.

Scientific Reasoning: Inductive vs. Deductive

• Inductive Reasoning: Bottom-up approach from specific observations to generalizations.

  • Example: Observing multiple barking dogs to hypothesize that all dogs bark.

• Deductive Reasoning: Top-down logic from general premises to specific conclusions.

  • Example: "All mammals have kidneys; whales are mammals; therefore, whales have kidneys."

Logical Fallacies in Reasoning

• Ad Hominem Fallacy: Responding to data by attacking the person instead of addressing the information itself.

• Example: Dismissing scientific findings based on the presenter's political affiliation rather than the validity of their data.

Scientific Inquiry in Complex Situations: Case of Easter Island

• Example of Scientific Re-evaluation: Early theories suggested environmental destruction and warfare led to Rapa Nui's collapse.

• Further Investigation: Showed alternative explanations (disease, external contact) rather than initial theories of environmental misuse alone.

Scientific Proof and Consensus Science

• Uncertainty in Science: Models, theories, and laws are reliable but not absolute.

• Consensus Science: Widely supported by experts in a field, represents the most reliable scientific understanding.

• Frontier Science: New hypotheses or discoveries that have yet to gain full scientific validation.

Paradigm Shifts and Critical Evaluation of Scientific Information

• Paradigm Shift: A significant change in accepted scientific understanding (e.g., a major new discovery).

• Critical Analysis of Sources: Essential for understanding scientific news; verify credibility, check for biases, and consider alternative viewpoints.

3.02

Understanding Systems in Science

• System Definition: A set of interacting factors, studied to observe behaviors like the carbon cycle or leaf decomposition.

• System Components:

  1. Input: Matter, energy, or information entering the system.

  2. Flow Rate: Movement of matter, energy, or information through the system.

  3. Storage: Areas within the system where inputs accumulate temporarily.

  4. Output and Sinks: Outputs exiting the system and entering other parts of the environment (e.g., atmosphere, oceans).

Role of Models in Science

• Purpose: To simulate system behaviors and test hypotheses.

• Mathematical Models: Use equations to predict future scenarios, especially when experimentation is infeasible or costly.

• Limitation: Restricted by data and assumptions within the model.

Types of Feedback Loops

• Positive Feedback Loop: Reinforces changes, continuing a process (e.g., polar ice melt leading to increased heat absorption).

• Negative Feedback Loop: Reverses changes, reducing the impact of a process (e.g., recycling lessening environmental waste).

Concept of Delay and Environmental Threshold

• Delay: A lag before effects appear, like smoking’s long-term health effects.

• Threshold: The point where changes become significant or irreversible, such as excessive population growth or ecosystem degradation.

Synergy and Environmental Complexity

• Synergy: Interactions between variables create a combined effect greater than individual impacts.

• Law of Conservation of Problems: Solutions in complex systems often create new issues (e.g., fertilizers improving crops but polluting water sources).

Environmental Surprises and System Imbalance

• Environmental Surprises:

  1. Threshold Breach: Reaching a tipping point leading to destabilization.

  2. Synergistic Effects: Combined effects of variables leading to stronger impacts.

  3. Chaos Events: Unpredictable occurrences like natural disasters or non-native species invasions.

• Prevention: Researching limits, refining models, promoting sustainable practices, and minimizing negative environmental impacts.

3.03

Basics of Matter

• Definition: Matter is anything that takes up space and has mass, composed of atoms.

• Atoms: Made up of protons (positive), neutrons (neutral), and electrons (negative).

• Elements and Compounds:

  • Elements: Pure substances with only one type of atom (e.g., gold, helium).

  • Compounds: Two or more atoms bound together (e.g., H2O, NaCl).

Atoms and the Periodic Table

• Atomic Number: Number of protons in the nucleus, defining the element.

• Mass Number: Total mass of the nucleus (protons + neutrons).

• Isotopes: Variants of elements with different neutron counts, impacting atomic mass.

• Ions: Atoms with extra or fewer electrons, giving them a net charge.

Types of Bonds

• Ionic Bonds: Atoms transfer electrons (e.g., NaCl).

• Covalent Bonds: Atoms share electrons (e.g., H2O).

States of Matter

• Solid, Liquid, Gas: Classified by kinetic energy.

• Plasma: A high-energy state of matter found in stars, lightning, and certain light sources.

Organic vs. Inorganic Compounds

• Organic Compounds: Carbon-based, covalent, including hydrocarbons and complex molecules like DNA.

• Inorganic Compounds: Non-carbon-based, including salts and water.

Quality of Matter

• High-Quality Matter: Concentrated, easily accessible, high potential as a resource.

• Low-Quality Matter: Dilute, less accessible, low usability.

Introduction to Energy

• Energy Definition: The ability to do work and transfer heat.

• Types of Energy:

  • Kinetic Energy: Energy of movement (e.g., wind, water flow).

  • Potential Energy: Stored energy (e.g., rock on a hill, ATP in cells).

• Electromagnetic Radiation: Includes visible light, gamma rays, UV radiation; classified by wavelength and energy.

  • Ionizing Radiation: High-energy radiation that can ionize atoms (e.g., gamma rays, UV).

  • Non-Ionizing Radiation: Includes visible light, not powerful enough to ionize atoms.

Heat and Energy Transfer

• Heat Transfer:

  • Radiation: Heat transfer via energy waves.

  • Conduction: Direct transfer via molecular collisions (e.g., heat through metal).

  • Convection: Heat transfer through fluid movement (e.g., air currents, ocean currents).

• Quality of Energy: Higher-quality energy (like conduction) is more useful for work compared to dispersed energy.

3.04

Law of Conservation of Matter and Types of Changes

Law of Conservation of Matter

• Definition: Matter cannot be created or destroyed; it only changes forms.

• Implications: Waste and pollutants don’t simply “go away.” They transform, potentially persisting in the environment.

Types of Changes Matter Can Undergo

1. Physical Change: Alters appearance, not composition (e.g., tearing paper, melting ice).

2. Chemical Change: Changes the composition, creating new substances (e.g., burning coal, forming CO2).

3. Nuclear Change: Alters the nucleus, involving radioactive decay, nuclear fission, or fusion.

Pollutants and Persistence

• Pollutants are classified by chemical nature and persistence.

  • Degradable: Can be broken down by natural processes (e.g., organic matter).

  • Slowly Degradable: Persists for long periods (e.g., DDT, plastics).

  • Non-Degradable: Remains indefinitely, like mercury and lead.

Nuclear Change Details

• Radioactive Decay: Unstable isotopes emit particles or radiation at a fixed rate until stabilizing.

  • Half-Life: Time for half the radioactive isotopes to decay, used in radiometric dating.

• Types of Radiation:

  • Alpha: Low penetration, stopped by paper.

  • Beta: Moderate penetration, can penetrate skin.

  • Gamma: High penetration, only stopped by thick concrete; most dangerous.

Nuclear Fission vs. Nuclear Fusion

• Nuclear Fission: Splitting heavy nuclei (e.g., Uranium-235) into lighter nuclei, releasing energy.

  • Used in nuclear power plants and atomic bombs (uncontrolled).

• Nuclear Fusion: Combining lighter nuclei (e.g., hydrogen atoms on the Sun) into heavier ones, releasing more energy than fission.

  • Requires extremely high temperatures and pressures; not yet feasible for controlled energy on Earth.

3.05

Thermodynamics and Energy Quality

First Law of Thermodynamics: Law of Conservation of Energy

• Definition: Energy cannot be created or destroyed, only transformed.

• Implication: Energy input equals energy output, but energy transformations can lead to less usable forms.

Second Law of Thermodynamics: Entropy and Energy Degradation

• Definition: When energy changes form, it partially degrades to lower-quality energy (often as heat), reducing the ability for useful work.

• Example: Only about 5% of the electrical energy in an incandescent bulb is useful light; the rest is lost as heat.

• Real-Life Effects:

  • In a food chain, energy degrades as it moves from plants (solar energy stored in chemical bonds) to animals (kinetic energy), and each step results in energy loss as heat.

  • High-energy sources like fossil fuels lose efficiency over time through degradation.

  • Recycling also involves energy inputs that contribute to overall entropy, making 100% efficiency impossible.

Thermodynamic Systems

• Open System: Exchanges both energy and matter with surroundings (e.g., biomes, human activities).

• Closed System: Exchanges only energy, not matter (e.g., Earth with respect to matter, receiving energy from the Sun).

• Isolated System: Exchanges neither matter nor energy with surroundings (e.g., soup in a closed thermos).

Entropy and Environmental Impact

• Entropy: Entropy, the measure of disorder, increases with every energy exchange due to heat loss.

• High-Throughput Economies: Industrialized nations often exhibit high-throughput economies, where the high use of resources leads to waste accumulation in sinks (e.g., air, soil).

• Low-Throughput Economies: A low-waste model focused on recycling, reusing, and reducing pollution to conserve energy and natural resources, though still limited by thermodynamic laws.

Biological Systems and Entropy

• Decreasing Local Entropy: Organisms can create order from disorder (e.g., plants using sunlight for photosynthesis), but this is balanced by increases in entropy in the wider environment.

• Cellular Respiration: Converts sugar into energy in mitochondria, creating order at a cellular level but ultimately increasing the overall system's entropy.

Thermodynamics and Recycling

• Recycling requires more energy than the resources saved, leading to increased entropy.

• Although recycling helps reduce waste temporarily, it does not eliminate the continuous increase in entropy and energy degradation.

Unit 2

Section 4- Ecosystems

4.01

Ecology: Study of relationships between organisms and their environment.

• Key Figures: George Evelyn Hutchinson ("father of modern ecology"), EO Wilson.

Basic Biological Principles:

• Organisms: Living forms; basic unit is the cell.

• Types of Cells:

  • Eukaryotic: Have a nucleus (e.g., plants, animals).

  • Prokaryotic: No nucleus, single-celled (e.g., bacteria).

Classification of Organisms:

• Organized from domains down to species.

• Species: Organisms with similar genetic makeup, biochemistry, appearance, and behavior; can produce fertile offspring.

• Population: Group of the same species in a specific area (e.g., ladybugs in a garden).

Genetic Diversity:

• Caused by genetic mutations and sexual reproduction.

• Increases survival chances by creating variations that adapt to environmental changes.

Habitats and Communities:

• Habitat: Physical location occupied by organisms (e.g., forest, ocean).

• Community: Different populations of species coexisting in a habitat.

Ecosystems:

• A biological community plus abiotic (nonliving) factors like soil, water, and weather.

• Ecosystems can be large (forest) or small (vernal pool).

• Human-made ecosystems include farms and reservoirs.

Biomes:

• Large ecological regions classified by climate and vegetation.

• Five general types: aquatic, desert, forest, grassland, tundra.

• More specific biomes include anthropogenic (human-affected) biomes and dermal biomes (skin ecosystems).

Biosphere:

• Collection of all biomes on Earth, forming the global ecosystem.

Ecosystem Services (Natural benefits provided by ecosystems):

• Water Purification: Wetlands clean water.

• Nutrient Cycling: Circulates essential nutrients.

• Pest Control: Naturally regulated by ecosystem balance.

• Sustainable Food & Medicine: Biodiversity supports agriculture and health.

• Coastal Protection: Coral reefs and wetlands buffer wave impacts.

• Erosion Prevention: Plant roots stabilize soil.

• Air Filtration: Photosynthesis cleans the air.

Principles of Sustainability:

• Use renewable energy.

• Recycle nutrients naturally.

4.02

Earth’s Unique Life Support Systems

• Earth is the only known planet supporting life (as of 2018).

• Key systems: Atmosphere, Hydrosphere, Lithosphere, Biosphere.

Atmosphere

• Thin air layer surrounding Earth; essential for life.

• Troposphere: Inner layer (78% nitrogen, 21% oxygen).

• Stratosphere: Contains ozone layer.

• Higher layers (mesosphere, thermosphere, exosphere) lack life.

Hydrosphere

• Earth's water: found in oceans, underground, ice caps, permafrost, and as vapor in the atmosphere.

Lithosphere

• Land/rock layer, includes Earth's crust and upper mantle.

• Contains minerals and fossil fuels.

Biosphere

• Life-supporting zone; overlaps parts of the atmosphere, hydrosphere, and lithosphere.

• Extends from ocean depths to mountain peaks.

• Ecology focuses on understanding interactions within this layer.

Energy Flow and the Sun

• Life relies on one-way flow of energy from the Sun:

  • Flows through organisms via the food web.

  • Energy exits as low-quality radiant heat.

• Biogeochemical cycles recycle vital elements through biotic/abiotic parts of the environment.

• Gravity holds the atmosphere and drives chemical cycles.

Solar Energy's Role

• Warms and lights Earth, powers photosynthesis, cycles nutrients, and influences weather/climate.

• 30% of solar radiation reflects off the atmosphere; 50% reaches Earth's surface.

Greenhouse Effect

• Greenhouse gasses (water vapor, CO₂, methane, nitrous oxide, ozone) retain heat, making Earth habitable.

• Essential natural effect, though excess anthropogenic greenhouse gasses raise concerns.

Biomes and Climate

• Biomes: Regions with distinct climate and life forms (flora/fauna).

• Climate affects biome distribution (deserts, forests, tundra, etc.).

• Aquatic biomes include freshwater (lakes, rivers) and marine (oceans, coral reefs).

• Ecotones: Transitional zones between biomes with species from each.

Ecosystem Components

• Abiotic: Non-living elements (water, air, sunlight, nutrients).

• Biotic: Living organisms categorized as:

  • Producers (Autotrophs): Plants and chemosynthetic bacteria.

  • Consumers (Heterotrophs): Herbivores, omnivores, carnivores.

  • Scavengers, Detritivores, Decomposers: Essential for recycling organic matter.

Vital Biotic Processes

• Aerobic Respiration: Oxygen-dependent.

• Anaerobic Respiration: Oxygen-free; includes fermentation.

• Photosynthesis: Uses CO₂ and water to produce oxygen and carbohydrates.

Range of Tolerance and Limiting Factors

• Each species has a tolerance range for environmental conditions.

• Shelford’s Law of Tolerance: Extremes in factors can limit species survival.

• Limiting Factors: Key abiotic elements like water or temperature that restrict growth.

Biodiversity

• Vital for ecosystem services like food, raw materials, pest control, and nutrient cycling.

• Types:

  • Genetic: Diversity within species.

  • Species: Variety of organisms in a habitat.

  • Ecological: Variety of ecosystems.

  • Functional: Diversity in energy and matter cycling processes.

• Loss of biodiversity weakens ecosystem resilience and adaptability.

Conclusion

• Importance of biodiversity and Earth's life-support systems in sustaining life.

• Zone of Intolerance: Region unsuitable for survival of any population members.

4.03

Energy Flow in Ecosystems

• Ecosystems and Energy: Energy flows through ecosystems in a specific sequence, often in a direct line (food chain) or as an interconnected network (food web).

• Matter Cycling: Most matter within ecosystems is recycled or reused at some point in the cycle.

Food Chain and Trophic Levels

• Food Chain: A sequence of trophic levels where:

  • Producers (plants) perform photosynthesis to capture solar energy.

  • Primary Consumers (herbivores) consume producers.

  • Secondary Consumers (carnivores, omnivores, scavengers) feed on herbivores.

  • Tertiary Consumers (top-level predators) feed on secondary consumers.

• Energetics: Study of energy flow, focusing on how solar energy is transformed and passed through each trophic level.

• Photosynthesis Equation: Sunlight + Water + CO₂ ➔ Oxygen + Glucose.

• Cellular Respiration: Glucose + Oxygen ➔ CO₂ + Water + ATP (energy).

Chemosynthesis

• Alternative to Photosynthesis: Some bacteria use chemical energy (from hydrogen sulfide) instead of sunlight to produce glucose, especially near hydrothermal vents.

Food Webs

• Complex Networks: Food webs are more intricate than food chains; organisms often occupy multiple trophic levels.

• Biomass: Each trophic level contains a measurable amount of organic matter (biomass).

Energy Loss in Ecosystems

• Ecological Efficiency: Only ~10% of energy is transferred as biomass to the next trophic level; the rest is lost as heat (second law of thermodynamics).

• Energy Flow Pyramid: Visualizes the decline in energy available at each trophic level, often following the "rule of 10".

Productivity in Ecosystems

• Gross Primary Productivity (GPP): Total rate of solar energy conversion by producers.

• Net Primary Productivity (NPP): GPP minus the energy producers use for respiration; reflects energy available for higher trophic levels.

• High Productivity Areas: Shallow waters, coral reefs, and upwelling zones in the ocean; on land, forests have high GPP.

Human Impact and Carrying Capacity

• Impact on NPP: Human activities directly affect ~40% of terrestrial NPP through resource use and environmental changes.

• Diet and Energy Efficiency: Eating at lower trophic levels (e.g., grains vs. meat) conserves energy by reducing trophic transfers.

Ecological Research Methods

• Field Research: Observing ecosystems over time to gather direct data on ecosystem interactions.

• Remote Sensing and GIS: Satellites and aircraft track environmental conditions and changes in resources, pollution, and health.

• Laboratory Research: Controlled experiments in culture tubes, tanks, and chambers to simulate environmental conditions.

• Systems Analysis: Mathematical models simulate complex ecosystems and predict responses to environmental changes.

4.04

Overview of Biogeochemical Cycles

• Cycles: Nutrient cycles that supply all essential atoms and molecules for living organisms.

• Components: Cycles involve exchanges between abiotic (air, water, soil, rocks) and biotic forms.

• Types of Cycles: Include hydrologic, atmospheric, and sedimentary cycles, with human activities often impacting them.

Hydrologic (Water) Cycle

• Processes: Water cycles through evaporation, condensation, and precipitation, with additional processes like transpiration and sublimation.

• Residence Time: Duration a water molecule stays in one place, varying from days to thousands of years.

• Human Impact:

  • Groundwater Depletion: Overuse of surface and groundwater resources.

  • Saltwater Intrusion: Ocean water seeps into empty groundwater spaces.

  • Runoff and Erosion: Increased by clearing vegetation, reducing groundwater infiltration.

  • Pollutants: Introduced nutrients and pollutants reduce water quality and disrupt the cycle’s natural purification.

Atmospheric Cycles

1. Carbon Cycle:

   • Role of CO₂: Acts as a natural thermostat for Earth.

   • Human Impacts:

     • Deforestation: Reduces CO₂ absorption.

     • Fossil Fuels: Releases excess CO₂, warming the atmosphere.

2. Nitrogen Cycle:

   • Fixation: Conversion of atmospheric nitrogen (N₂) to ammonia (NH₃) by bacteria, making it available to plants.

   • Nitrification: Ammonia converts to nitrite and nitrate ions for plant and bacterial use.

   • Assimilation: Plants absorb ammonia, ammonium, and nitrates from soil and water.

   • Ammonification: Organic nitrogen is converted back to ammonia and ammonium by bacteria.

   • Denitrification: Conversion of ammonia back to nitrogen gas (N₂).

   • Human Impacts:

     • Acid Rain: Burning fuels releases nitric oxide, leading to acid rain.

     • Nitrous Oxide: Livestock waste adds nitrous oxide, depleting ozone.

     • Agricultural Runoff: Excess nitrogen in water bodies depletes oxygen and harms aquatic life.

Sedimentary Cycles

1. Phosphorus Cycle:

   • Sources: Found in rocks, water, and living organisms.

   • Human Impacts:

     • Fertilizers and Detergents: Mining of phosphate rocks.

     • Soil Erosion: Phosphate runoff reduces soil nutrients.

     • Aquatic Pollution: Excess phosphorus in water depletes oxygen, disrupting ecosystems.

2. Sulfur Cycle:

   • Sources: Stored in rocks, minerals, and salts in ocean sediments.

   • Atmospheric Entry: Released by decomposers and volcanic eruptions.

   • Human Impacts:

     • Burning of Sulfur Compounds: Releases sulfur dioxide (SO₂), which forms sulfur trioxide (SO₃) and sulfuric acid, causing acid rain.

Section 5- Evolutions and Biodiversity

5.01

Introduction:

• Exploring the beginning of our universe, evolution, and biogeochemical cycles.

• Unanswered questions addressed by scientists through chemical analysis and radioactive dating of fossils and rocks.

Two Phases of Evolution:

• Chemical Evolution (4.7-4.8 billion years ago): Formation of organic molecules and polymers, leading to proto-cells and prokaryotes.

• Biological Evolution: Started with simple prokaryotic cells, eventually leading to complex eukaryotic organisms.

Chemical Evolution Process:

• Cosmic Dust Cloud Condensation: Molten formation from meteorite impacts and radioactive decay.

• Crust Formation: Water vapor and CO₂ released from the Earth’s crust, cooling to form rain and eroding minerals into early seas.

• Early Atmosphere Composition: Mainly CO₂, nitrogen, and water vapor—no oxygen due to lack of aerobic organisms.

Origin of Organic Molecules:

• Miller-Urey Experiment (1950s): Showed that organic molecules could form from simple compounds on early Earth.

• Hydrothermal Vents: Possible sites for organic molecule formation, influenced by mineral-rich molten rocks.

• Meteorite Evidence (1977): Discovery of amino acids suggested possible extraterrestrial influence on life.

Transition to Life:

• Early organic molecules underwent reactions, forming RNA and membrane-bound structures.

• These structures could grow and divide, leading to the first prokaryotic cells.

Biological Evolution Timeline:

• 3.5-3.8 Billion Years Ago: Formation of prokaryotic cells in shallow seas.

• 2.3-2.5 Billion Years Ago: Cyanobacteria emerged, releasing oxygen into the atmosphere.

• 1.2 Billion Years Ago: First eukaryotic cells developed, capable of sexual reproduction, increasing genetic diversity.

Tracing Evolution:

• Scientists study DNA, organic material in ice cores, and chemical/radioactive dating of fossils.

• Evolution continues today, with populations evolving, not individuals.

Theory of Evolution:

• Supported by most biologists, the theory suggests all species evolved from earlier species.

• Microevolution: Small changes within populations.

• Macroevolution: Long-term changes across species groups.

5.02

Introduction:

• Microevolution and macroevolution contribute to the variety of life on Earth.

• Macroevolution: Long-term changes across species groups, like human and chimpanzee common ancestry.

• Microevolution: Small genetic changes within populations over generations, building genetic variability.

Gene Pool and Genetic Variability:

• The gene pool is the sum of all genes in a population.

• Alleles are different forms of the same genes that shuffle during reproduction, creating genetic variability.

• Microevolution results from mutation, natural selection, gene flow, and genetic drift.

Processes Contributing to Microevolution:

• Mutations: Random DNA changes that introduce new alleles; some are beneficial, leading to genetic adaptation.

• Natural Selection: Favors individuals with advantageous traits, enhancing their chances to reproduce.

  • Types of Natural Selection:

    • Directional: Favors one extreme trait (e.g., peppered moths).

    • Stabilizing: Favors average traits (e.g., human birth weights).

    • Disruptive: Favors extreme traits, reducing intermediate ones (e.g., Darwin's finches).

• Gene Flow: Movement of genes between populations, often increasing genetic variation.

• Genetic Drift: Random allele frequency changes, more impactful in small populations.

  • Bottleneck Effect: Population drastically reduces, limiting genetic diversity (e.g., elephant seals).

  • Founder Effect: Small group colonizes new area with limited gene pool, leading to genetic isolation (e.g., Amish community).

Co-evolution:

• Species evolve in response to each other, adapting in tandem (e.g., cactus thorns and bird beaks).

5.03

Introduction to Macroevolution:

• Unlike the short-term changes in microevolution, macroevolution refers to long-term evolutionary changes across species.

• It explains the evolution of new species or a species transforming into another over extended periods.

Theories of Evolutionary Change:

• Gradualism Model: Evolution occurs slowly over millions of years through small, continuous changes.

• Punctuated Equilibrium Model: Evolution has long stable periods with short bursts of rapid change.

Genetic Divergence and Speciation:

• Genetic Divergence: Separate populations evolve independently, accumulating unique mutations and adaptations.

• Speciation: The formation of new species due to reproductive isolation and natural selection acting on isolated populations.

Modes of Speciation:

• Allopatric Speciation: Physical separation of a large population (e.g., island or mountain barriers) leads to independent evolution.

• Peripatric Speciation: A small, isolated group diverges from the main population, often leading to rapid evolution due to smaller gene pools.

• Parapatric Speciation: Part of the population diverges in a contiguous area due to partial barriers or changing behaviors.

• Sympatric Speciation: Speciation within a shared space, often due to behavioral changes or mutations causing reproductive isolation.

Types of Evolution:

• Divergent Evolution: A single species evolves into distinct forms adapted to different environments, like Darwin's finches with specialized beaks.

• Convergent Evolution: Different species independently evolve similar traits due to similar environmental pressures, e.g., streamlined bodies in dolphins and sharks.

5.04

Ecological Niches:

• Each species' role in an ecosystem, its ecological niche, includes the adaptations it has evolved to survive and reproduce under specific environmental conditions.

• The fundamental niche refers to all potential conditions a species could theoretically tolerate, while the realized niche is the actual conditions in which it lives, shaped by factors like competition and predation.

Generalists vs. Specialists:

• Generalist Species: Have broad niches and can thrive in varied environments (e.g., raccoons, rats), which makes them more adaptable to environmental changes.

• Specialist Species: Have narrow niches with specific needs (e.g., koalas, orchid mantises). They thrive in stable environments but are vulnerable to change.

Extinction Patterns:

• Background Extinction: The natural, ongoing loss of species due to gradual environmental changes (typically 1-5 species per year).

• Mass Extinctions: Occur when extinction rates skyrocket due to catastrophic events, leading to the loss of up to 75% of species. We are currently experiencing the sixth mass extinction, largely due to human activities.

Biodiversity and Adaptation:

• Speciation increases biodiversity, while extinction reduces it.

• Adaptive Radiation: Following a mass extinction, surviving species evolve rapidly, filling empty niches with new traits derived from shared ancestors. Darwin’s finches are a classic example.

Anthropogenic Impact on Ecosystems:

• Human activities, including habitat destruction, pollution, introduction of invasive species, overuse of antibiotics, and resource depletion, accelerate extinction and reduce biodiversity.

• Ecosystem Simplification: Reduces niche diversity by destroying habitats, reducing biodiversity, and disrupting ecological balance.

• Non-Native Species: Introduced species often lack natural predators in their new environments, allowing them to outcompete native species, as seen with kudzu in the southern U.S.

Common Misconceptions about Evolution:

• "Survival of the Fittest" is about reproductive success, not strength.

• Natural Selection is not about competition between individuals but the advantage well-adapted organisms have in surviving and reproducing.

• Human Evolution: Humans did not evolve directly from apes but share a common ancestor.

• Perfection in Evolution: Natural selection is about adaptation to changing environments, with no goal of achieving perfection.

Section 6 - Terrestrial Biogeography

6.01

Wind and Atmospheric Properties:

• Wind distributes nutrients, viruses, pesticides, and pollution globally.

• Volcanic ash enriches soil with trace minerals despite temporary climate alterations.

• The troposphere contains most of Earth's air, governing weather conditions such as temperature, pressure, humidity, and precipitation.

Weather Fundamentals:

• Weather is the short-term state of the troposphere.

• Boundaries of air masses create dramatic weather changes.

• Convection: Warm air rises, cools, condenses (causing precipitation), sinks, and flows as wind.

Fronts and Pressure Systems:

• Warm fronts: Warm air rises, condenses into clouds, and results in drizzle.

• Cold fronts: Cold air wedges under warm air, forming thunderheads and winds.

• High pressure: Cool, descending air causes fair weather.

• Low pressure: Warm, rising air results in clouds and storms.

Extreme Weather Events:

• Tornadoes: Over land, fueled by warm earth.

• Tropical cyclones: Over warm ocean waters (hurricanes in Atlantic, typhoons in Pacific).

• Ecological benefits: Nutrient redistribution and natural flushing of coastal ecosystems.

Climate vs. Weather:

• Weather: Day-to-day tropospheric changes.

• Climate: Long-term patterns of temperature and precipitation influenced by:

  • Air circulation

  • Ocean currents

  • Earth's rotation and tilt

  • Topography

Earth’s Heat Distribution:

• Sunlight strikes equator directly, creating intense warmth.

• Tilt of Earth’s axis (23.5°) causes seasonal variations.

• Coriolis Effect deflects air and water currents:

  • Right in Northern Hemisphere, left in Southern Hemisphere.

Ocean Currents and ENSO:

• Ocean currents regulate climate by distributing heat.

• Upwelling brings nutrient-rich waters, supporting marine life.

• ENSO (El Niño-Southern Oscillation): Periodic reversal of currents affecting global weather.

• La Niña: Cooler counterpart of El Niño, altering storm and rainfall patterns.

Microclimates:

• Rainshadow Effect: Mountains block moist air, causing dry leeward areas.

• Urban Heat Islands: Cities absorb heat, raising temperatures.

• Coastal regions: Daily land-sea breezes regulate temperatures.

Greenhouse Effect and Ozone Layer:

• Greenhouse gases regulate Earth's temperature but can cause excessive warming.

• Stratospheric ozone layer absorbs UV radiation and maintains thermal balance.

• Ozone depletion is improving; Antarctic hole expected to close by 2050.

6.02

General Biomes Overview

• Living organisms adapt to specific climates on every continent.

• Biomes are influenced by latitude, altitude, ocean currents, temperature, and precipitation.

• Biomes transition into one another through ecotones and vary due to microclimates (elevation, soil types, disturbances).

Desert Biomes

Key Features:

• Cover 30% of Earth, located 15°-35° north/south of the equator.

• Precipitation < evaporation. Sparse vegetation.

• Wide temperature variations (hot days, cold nights).

Types of Deserts:

1. Tropical Deserts:

   • E.g., Sahara Desert.

   • High year-round temperatures, very low precipitation.

2. Temperate Deserts:

   • E.g., Mojave Desert.

   • Hot summers, cooler winters, slightly more rain than tropical deserts.

3. Cold/Polar Deserts:

   • E.g., Gobi Desert.

   • Cold winters, warm summers, low precipitation.

Plant Adaptations:

• Store water (e.g., cacti with shallow roots).

• Drop leaves or grow slowly (e.g., mesquite, creosote).

• Dormant seeds germinate after rain.

Animal Adaptations:

• Conserve water, e.g., thick exoskeletons, torpid states.

• Examples: desert tortoises, kangaroo rats, gila monsters.

Human Impacts:

• Cities, soil salinization, mining, toxic waste storage, off-road vehicles.

Grassland Biomes

Key Features:

• Receive more precipitation than deserts, less than forests.

• Found mainly on continental interiors.

Types of Grasslands:

1. Tropical Grasslands (Savannas):

   • High temperatures, seasonal rainfall.

   • Examples: Africa, South America, Australia.

   • Large herbivores (zebras, elephants, giraffes) minimize competition.

2. Temperate Grasslands:

   • Hot summers, cold winters, uneven rainfall.

   • Examples: Great Plains (US), pampas (South America), steppes (Asia).

   • Rich soil but vulnerable to wind erosion if plowed.

3. Polar Grasslands (Arctic Tundra):

   • Found south of polar ice caps.

   • Treeless, mosses, and lichens dominate.

   • Permafrost causes seasonal sogginess, attracting migratory birds.

4. Alpine Tundra:

   • Above the treeline in mountains.

   • Similar vegetation to Arctic tundra, no permafrost.

5. Chaparral (Temperate Shrubland):

   • Found in Mediterranean climates (hot, dry summers; mild, rainy winters).

   • Plants adapted to fire with nutrient-storing roots or fire-dependent seeds.

Human Impacts:

• Overgrazing, farming, CO₂ from burning grasslands, oil production.

6.03

Forest Biomes Overview

• Found in areas with high precipitation and diverse ecosystems.

• Three main types: tropical, temperate, boreal (polar).

• Trees and plants provide habitats and are part of a complex food web.

Tropical Forests

Features:

• Near the equator, warm year-round (25–30°C).

• High humidity, abundant rainfall (100–275 cm annually).

Ecological Characteristics:

• Broadleaf evergreens dominate; supports 75% of terrestrial species.

• Nutrients stored in plant biomass, not soil.

• High biodiversity with layered niches (canopy to soil).

• Plants rely on pollinators (birds, bats, insects) due to minimal wind.

Tropical Deciduous Forests:

• Warm year-round but distinct wet/dry seasons.

• Trees mix deciduous and drought-tolerant evergreens.

Temperate Deciduous Forests

Features:

• Moderate temperatures; seasonal changes.

• Steady precipitation year-round.

Ecological Characteristics:

• Dominant trees: oak, maple, sycamore, poplar.

• Nutrients stored in leaf litter, supporting ground-level plants.

• Fauna: deer, raccoons, squirrels; many predators (bears, wolves) are extinct.

• Habitat loss and monoculture practices reduce biodiversity.

Boreal Forests (Taiga)

Features:

• Sub-arctic regions with long, cold winters and short, mild summers.

• Low biodiversity due to extreme cold.

Ecological Characteristics:

• Cone-bearing trees with waxy needles adapted to cold.

• Sparse forest floor due to slow decomposition and acidic soil.

• Wildlife includes moose, wolves, snowshoe hares, and owls.

Temperate Rainforests

• Near coasts, buffered by ocean temperatures (mild winters, cool summers).

• Dense trees (redwoods, Douglas firs) benefit from summer fog.

Mountain Biomes

• Cover 20% of Earth's surface; high biodiversity due to varied climates.

• Altitudinal changes affect vegetation, climate, and soil.

• Serve as biodiversity sanctuaries and regulate the hydrologic cycle.

Human Impacts:

• Timber extraction, dams, and recreational activities (hiking, skiing).

• Increased erosion and habitat destruction from development.

Anthropogenic Biomes

• Created or altered by humans (e.g., cities, croplands, rangelands).

• Mark irreversible human-land interactions.

Impact:

• Transform ecosystems and traditional biomes.

• Offer potential for biosphere management if approached sustainably.

Section 7 - Aquatic Life Zones

7.01

Earth's Surface: Water covers 75% of the Earth's surface.

Delineation by Salinity: Organisms in aquatic life zones are dispersed based on salinity, not climate or vegetation.

• Two main types: Saltwater and Freshwater biomes.

Characteristics of Aquatic Biomes

• Saltwater Biomes: Oceans, mangrove forests, coastal marshes, coral reefs, coastlines, estuaries.

• Freshwater Biomes: Lakes, ponds, streams, rivers, inland wetlands.

• Primary Producers: Phytoplankton produce 50-80% of atmospheric oxygen.

• Food Web Foundation: Zooplankton feed on phytoplankton and are consumed by higher-level predators.

• Zones of Life:

  • Benthic: Bottom dwellers (mussels, worms, crabs).

  • Nekton: Strong swimmers (turtles, fish, dolphins).

  • Decomposers: Bacteria recycle nutrients.

Unique Features and Challenges

• Fluidity and Boundaries: Lack of defined physical boundaries, complexity in food webs, and nutrient cycling.

• Scale: Aquatic biomes cover vast areas, making study difficult.

• Advantages: Buoyancy, constant temperatures, nutrient abundance, and protection from UV light.

• Disadvantages:

  • Sensitivity to temperature changes.

  • Pollution accumulation.

  • Larval dispersal reduces survival near parent habitats.

Environmental and Nutritional Factors

• Limiting Factors:

  • Temperature, sunlight access, dissolved oxygen, nutrients like nitrogen, carbon dioxide, and phosphorus.

• Eutrophication: Excessive phosphorus leads to algal blooms, oxygen depletion, and hypoxia.

• Upwelling: Brings nutrient-rich cold water to the surface, supporting high productivity.

• Dissolved Oxygen: Influenced by temperature, photosynthesis, and water movement.

Carbon Dynamics

• Carbon Sink: Oceans absorb 20-35% of anthropogenic CO₂ but are impacted by warming and acidification.

• Arctic Melting: Releases trapped CO₂, exacerbating atmospheric levels.

Net Primary Productivity (NPP)

• High NPP: Surface waters, shallow streams, ponds, and upwelling zones.

• Low NPP: Open oceans and eutrophication zones.

7.02

Ocean Composition and Salinity:

• Oceans cover 71% of Earth's surface, supporting 250,000 species.

• Seawater has 3.5% dissolved minerals, with salinity averaging 35 ppt.

Marine Life Zones:

• Defined by light, depth, and distance from shore:

  • Euphotic Zone: Sunlit surface layer; supports photosynthesis.

  • Disphotic and Aphotic Zones: Dim and dark layers with decreasing oxygen and biodiversity.

  • Intertidal and Neritic Zones: Nearshore areas with diverse life.

  • Oceanic Zone: Deep waters with subzones like mesopelagic and abyssopelagic.

Marine Organism Classifications:

• Plankton: Drifting organisms, base of the food web.

• Nekton: Swimming organisms like fish and mammals.

• Benthic: Bottom-dwelling decomposers.

Specialized Habitats:

• Coral Reefs: Biodiverse, temperature-sensitive ecosystems.

• Estuaries and Wetlands: Brackish water zones with high productivity.

• Rocky and Sandy Shores: Adapted organisms facing fluctuating conditions.

Ecological and Economic Importance:

• Ecosystem services include climate moderation, nutrient cycling, storm buffering, and food provision.

• Economic benefits include fisheries, recreation, and resource extraction.

Human Impacts:

• Coastal development, pollution, overfishing, and climate change threaten these ecosystems.

• Coral bleaching, habitat destruction, and biodiversity loss are significant concerns.

7.03

Lentic Systems (Lakes & Ponds):

• Life Zones:

  • Littoral Zone: Shallow, near-shore with high biodiversity.

  • Limnetic Zone: Open water, primary photosynthesis zone.

  • Profundal Zone: Deep water, low light, adapted fish.

  • Benthic Zone: Bottom layer, low oxygen.

• Nutrient Levels:

  • Oligotrophic: Nutrient-poor, high oxygen, clear waters.

  • Eutrophic: Nutrient-rich, murky waters, high productivity.

• Stratification: Layers based on temperature (epilimnion, thermocline, hypolimnion).

Lotic Systems (Rivers & Streams):

• Characteristics:

  • Watershed: Areas draining into the system.

  • Source Area: High oxygen, fast-flowing.

  • Transition Area: Wider, slower streams, warmer waters.

  • Floodplain: Broad, flat areas, low oxygen, muddy.

• End Flow: Brackish wetlands before reaching the ocean.

Inland Wetlands:

• Types: Marshes, swamps, prairie potholes, bogs, and tundra.

• Ecological Services: Flood control, water purification, biodiversity support.

• Economic Services: Irrigation, hydroelectricity, recreation.

Human Impacts:

• River fragmentation, wetland destruction, and floodplain separation disrupt habitats, reduce biodiversity, and increase flooding risks.

Section 8- Community Ecology and Species Interaction

8.01

1. Community Characteristics

• Determined by interactions among species and the environment.

• Stability and biodiversity are central themes.

2. Defining Characteristics of Community Structure

• Stratification: Vertical/horizontal layers due to environmental factors (light, temperature, nutrients).

• Species Abundance: Relative number of individuals per species.

• Species Richness/Diversity: Number of different species present.

• Niche Structure: Number and uniqueness of ecological niches.

3. Biodiversity Distribution

• Uneven globally, highest in tropical rainforests, coral reefs, hydrothermal vents, and tropical lakes.

• Affected by:

  • Latitude: Biodiversity highest at the equator, decreases toward poles (e.g., ants and birds).

  • Depth (aquatic systems): High biodiversity at 0–2,000m depth; exceptions near hydrothermal vents (chemosynthesis).

  • Pollution (aquatic systems): Reduces species abundance/diversity (e.g., diatoms).

4. Theory of Island Biogeography

• Proposed by E.O. Wilson & Robert MacArthur.

• Biodiversity influenced by:

  • Immigration vs. Extinction Rates.

  • Island Size: Larger islands have lower extinction and higher immigration.

  • Proximity to Mainland: Closer islands have higher immigration rates.

• Applied to habitat fragments (e.g., national parks).

5. Species Roles in Ecosystems

• Native Species: Adapted to and thrive naturally in their ecosystem.

• Non-native Species: Introduced species; harmful ones are called invasive species.

  • Examples: Tumbleweed, invasive cattail, mongoose in Hawaii.

• Indicator Species: Signal ecosystem health (e.g., birds, trout, amphibians).

• Keystone Species: Critical for ecosystem balance.

  • Examples: Pisaster sea star, pollinators (bees, bats), top predators (sharks, lions), dung beetle.

6. Importance of Keystone Species

• Maintain structure, function, and biodiversity.

• Roles:

  • Pollination and seed dispersal.

  • Habitat modification (e.g., elephants).

  • Nutrient cycling (e.g., mycorrhizae fungi, dung beetle).

8.02

Overview of Species Interactions

• Species interactions are critical to ecosystem functioning and the niches species occupy.

• Relationships can be:

  1. Helpful

  2. Harmful

  3. Neutral

• Five main types:

  1. Competition

  2. Predator-prey relationships

  3. Parasitism

  4. Mutualism

  5. Commensalism

1. Competition

• Definition: When organisms vie for the same resources.

• Intraspecific Competition (within the same species):

  • Example: Desert plants secreting chemicals to inhibit nearby growth.

  • Example: Territorial animals (e.g., lions, rhinos) marking and defending areas.

  • Downside: Reduces genetic diversity and expends energy.

• Interspecific Competition (between different species):

  • Example: Dandelions competing with various plants using wind-dispersed seeds.

  • Two types:

    1. Interference Competition: One species limits another’s resource access (e.g., territorial hummingbirds).

    2. Exploitation Competition: Species exploit shared resources differently (e.g., humans deforesting faster than ecosystems can recover).

• Competitive Exclusion Principle:

  • No two species can occupy the same niche indefinitely with limited resources.

  • Leads to extinction or adaptation through resource partitioning.

• Resource Partitioning:

  • Example: Warblers feeding in different parts of the same tree.

  • Example: Owls hunting at night vs. hawks during the day.

2. Predator-Prey Relationships

• Definition: One species (predator) feeds on another (prey).

• Benefits:

  • Removes sick and weak individuals.

  • Improves genetic diversity in prey species.

• Predator Adaptations:

  • Speed (e.g., cheetahs).

  • Keen senses (e.g., eagles’ eyesight, Venus flytrap’s vibration detection).

  • Camouflage for ambush (e.g., praying mantises, snowy owls).

• Prey Adaptations:

  • Defensive behaviors (e.g., armadillos curling into balls).

  • Chemical warfare (e.g., skunks’ spray, poisonous plants like oleander).

  • Mimicry (e.g., viceroy butterflies imitating monarch butterflies).

  • Behavioral displays (e.g., blowfish puffing up).

3. Parasitism (Symbiotic Relationship)

• Definition: One species (parasite) benefits, while the host is harmed.

• Examples:

  • Internal: Tapeworms, disease-causing microorganisms.

  • External: Ticks, fleas, mistletoe.

  • Fungi: Athlete’s foot.

• Role in Ecosystems:

  • Regulates population sizes.

  • Promotes biodiversity by reducing competition.

4. Mutualism (Symbiotic Relationship)

• Definition: Both species benefit.

• Examples:

  • Pollination: Flowers and insects/birds/bats.

  • Nutritional mutualism: Lichen (algae and fungi), gut bacteria aiding digestion.

  • Protection and nutrition: Clownfish and sea anemones (protection for cleaning services).

5. Commensalism (Symbiotic Relationship)

• Definition: One species benefits, the other is unaffected.

• Examples:

  • Epiphytes (e.g., orchids) growing on tree trunks.

  • Herb sorrel thriving in the shade of redwood trees.

8.03

Introduction

• Ecosystems are dynamic and continuously changing.

• These changes transform young habitats into mature ecosystems (e.g., saplings into old-growth forests).

Types of Succession

Primary Succession

• Occurs in lifeless areas with no soil or sediment.

• Examples: Cooled lava, exposed rock from glacial retreat, abandoned parking lots.

Stages of Primary Succession:

1. Pioneer Species: Begin soil formation (e.g., lichens and mosses).

   • Lichens: Mutualistic relationship between algae (photosynthesis) and fungi (nutrients).

   • Contribute organic matter and secrete acids to break down rock.

2. Early Successional Plants: Low-growing grasses and herbs.

   • Roots help break rock; decomposition enriches soil.

3. Mid-Successional Plants: Shrubs and more resilient grasses.

   • Soil development supports larger plant species.

4. Late Successional Species: Shade-tolerant trees dominate.

   • Final stage of a mature ecosystem.

Secondary Succession

• Occurs in areas with existing soil but disturbed ecosystems.

• Examples: Burned forests, abandoned farms, polluted streams.

• Follows similar stages as primary succession but progresses faster due to existing soil and seed presence.

Stages of Ecosystem Development

1. Early Successional Stage:

   • Low species diversity, simple food chains, and limited niches.

   • Nutrient cycling and biomass are minimal.

2. Late Successional Stage:

   • High species diversity with complex food webs.

   • Efficient nutrient cycling and increased biomass.

Animal Succession

• Early: Generalists like quail and bobolink.

• Mid: Larger herbivores (e.g., moose, snowshoe hare).

• Late: Specialists like gray squirrels and martens.

• Wilderness species: Apex organisms like grizzly bears and condors.

Disturbances and Stability

• Natural Disturbances: Fires, floods, volcanic eruptions.

• Anthropogenic Disturbances: Urbanization, deforestation, pollution.

• Disturbances reset succession but can enhance biodiversity (e.g., fire germinating seeds).

Intermediate Disturbance Hypothesis

• Mild-to-moderate disturbances can increase species diversity by creating new niches.

Ecosystem Resilience and Stability

• Stability depends on:

  • Inertia: Resistance to disturbance.

  • Constancy: Population stability within resource limits.

  • Resilience: Recovery capacity after disturbances.

• Example: Grasslands recover from fires due to root-stored nutrients, while tropical rainforests struggle to regenerate after deforestation.

The Precautionary Principle

• Protect natural systems by preventing harm (e.g., conserve biodiversity and resources).

• Analogous to personal precautions like seatbelts or healthy eating.

8.04

Overview

• Winifred Frick is the Chief Scientist at Bat Conservation International (BCI).

• BCI’s mission: Protect global bat biodiversity.

• Dr. Frick is also an Associate Research Professor at UC Santa Cruz.

• Focus areas:

  • Ecology and conservation of bats.

  • Disease ecology (e.g., white-nose syndrome).

  • Impacts of climate change on bats.

  • Long-term research on desert bats in northwestern Mexico.

Key Insights

Science and Conservation

• Scientific Process:

  • Identify researchable questions.

  • Secure funding.

  • Conduct fieldwork and data analysis.

  • Communicate findings effectively.

• Collaboration is essential: modern science relies heavily on teamwork.

• Why Care About Bats?

  • Provide ecosystem services:

    • Control insect pests.

    • Pollinate commercially important plants.

    • Disperse seeds in tropical forests.

  • Represent ~25% of all mammalian biodiversity.

Misconceptions

• Common misconception: Bats are not important.

• Reality: They play crucial roles in maintaining ecosystem balance.

Career Journey

• Did not initially plan to become a scientist or focus on bats.

• Discovered a passion for science during college.

• Science is a creative process that requires problem-solving, communication, and diverse skills.

Advice for Students

• Embrace Curiosity:

  • Explore the natural world.

  • Pursue passions with an open mind.

• Take Risks:

  • Try new things, even if failure is possible.

  • Valuable learning often comes from failed attempts.

• Develop Skills:

  • Focus on communication and collaboration.

  • Build a strong foundation in math and science.

Current and Future Work

• White-Nose Syndrome:

  • Disease caused by a fungus, devastating bat populations in North America.

  • Efforts focus on solutions to protect bats.

• Global Conservation Projects:

  • Protecting critically endangered species with limited populations.

  • Ensuring survival of bats roosting in vulnerable caves.

• Vision:

  • Continue as Chief Scientist at BCI.

  • Balance research and actionable conservation efforts.

Takeaways

• Science is about curiosity, creativity, and problem-solving.

• Bats are vital for ecosystem health and biodiversity.

• Conservation efforts require dedication, collaboration, and adaptability.

• Climate change impacts biodiversity and requires urgent attention to mitigate its effects.