Ecology Final Exam Review PDF 2024

Anna O’Brien Exam Date : Monday Dec 16th, 2024 Ecology Final Exam Review Chapter 9 - Social Behaviors Key Concepts 1. Living in groups has costs and benefits. 2. There are many types of social interactions. 3. Eusocial species demons...

Anna O’Brien Exam Date : Monday Dec 16th, 2024 Ecology Final Exam Review Chapter 9 - Social Behaviors Key Concepts 1. Living in groups has costs and benefits. 2. There are many types of social interactions. 3. Eusocial species demonstrate extreme forms of social interactions. Definitions to Know Social Behaviors: Interactions with members of one’s own species, including mates, offspring, relatives, and unrelated individuals. Territory: Any area defended by individuals against intrusion by others. Dominance Hierarchy: A ranking among group members, typically determined by contests of strength or skill. Dilution Effect: A reduced risk of predation for individuals in a group. Benefits of Living in Groups 1. Protection from Predators: ○ Dilution Effect: Predation risk is shared among group members. ○ Larger groups can spend less time watching for predators and more time feeding. 2. Example: European goldfinches spend more time collectively watching for predators in larger flocks. 3. Finding Food and Mates: ○ Group members can locate rare food sources more easily. ○ Lek Behavior: Males display in groups to attract females. Example: Larger leks of ruffs attract more females, increasing mating success. Costs of Living in Groups 1. Predation and Parasitism: ○ Groups are more noticeable to predators. ○ Disease spreads more quickly in dense populations. 2. Resource Sharing and Aggression:  ○ Members must share limited resources, leading to competition. ○ Aggression within the group can increase. Territories and Dominance Hierarchies 1. Territories: ○ Defended for access to food, mates, or nesting sites. ○ Maintenance occurs if benefits outweigh defense costs. Example: Migratory birds establish territories for breeding. 2. Dominance Hierarchies: ○ Common in dense populations where defending a territory is impractical. ○ Once established, hierarchies minimize conflict. Example: First-ranked individuals dominate all others. Types of Social Interactions 1. Donor and Recipient: ○ Donor: Directs behavior. ○ Recipient: Receives the behavior. 2. Four Types of Interactions: ○ Cooperation: Both donor and recipient benefit. ○ Selfishness: Donor benefits, recipient is harmed. ○ Spitefulness: Both donor and recipient are harmed. ○ Altruism: Donor is harmed, recipient benefits. Extreme Social Interactions: Eusociality Found in species like bees, ants, and termites. Characteristics of eusocial species: ○ Cooperative brood care. ○ Division of labor into reproductive and non-reproductive castes. ○ Overlapping generations within a colony. Examples to Remember 1. Bacteria and Protists: ○ Use chemicals to communicate and react cooperatively or aggressively.  2. Plants: ○ Emit volatile chemicals to warn neighboring plants of damage. Study Tips 1. Understand Definitions: Be able to explain key terms like "dominance hierarchy" and "altruism." 2. Memorize Examples: Use examples (like goldfinches or ruffs) to contextualize concepts. 3. Compare Costs and Benefits: Be ready to discuss the trade-offs of living in groups. 4. Practice Application: Think about how these concepts apply to real-world ecological systems. Chapter 10 - Population Distribution Key Concepts 1. The distribution of populations is limited to ecologically suitable habitats. 2. Population distributions have five important characteristics. 3. Population abundance and density are related to geographic range and adult body size. 4. Dispersal is essential to colonizing new areas. 5. Many populations live in distinct patches of habitat. 6. The distribution properties of populations can be estimated. Definitions to Know Spatial Structure: The pattern of density and spacing of individuals in a population. Fundamental Niche: The range of abiotic conditions (e.g., temperature, humidity, salinity) under which a species can persist. Realized Niche: The range of abiotic and biotic conditions under which a species persists, usually narrower than the fundamental niche. Geographic Range: The total area covered by a population. Ecological Niche Modelling: The process of determining suitable habitat conditions for a species. Ecological Envelope: The predicted range of suitable ecological conditions for a species. Endemic Species: Species that live in a single, often isolated, location.  Cosmopolitan Species: Species with very large geographic ranges spanning several continents. Abundance: The total number of individuals in a population within a defined area. Density: The number of individuals per unit area or volume. Population Characteristics 1. Abundance: ○ Indicates whether a population is thriving or at risk of extinction. 2. Density: ○ Calculated as abundance divided by the area or volume of the habitat. 3. Dispersion: ○ Clustered: Individuals grouped around resources or in social groups. ○ Evenly Spaced: Uniform distances between individuals (e.g., territories). ○ Random: Independent positioning of individuals, rare due to environmental heterogeneity. 4. Dispersal: ○ Movement of individuals from one area to another, distinct from migration. ○ Essential for colonization, avoiding competition, and escaping predation. Ecological Niche Modelling and Examples Helps identify suitable habitats for conservation or predict invasive species spread. Case Study: The Chinese bushclover spread in the U.S. was predicted using niche modelling. Effects of Global Warming on Population Distribution Temperature changes shift geographic ranges of species. Example: North Sea fish species expanded northward as ocean temperatures increased by 2°C from 1977–2003. Study Tips 1. Understand Key Terms: Be familiar with concepts like "realized niche" and "ecological niche modelling."  2. Connect to Real-World Examples: Relate concepts to case studies like Chinese bushclover and North Sea fish populations. 3. Practice Definitions: Ensure clarity on terms like abundance, density, and dispersal. 4. Visualize Distributions: Practice identifying dispersion patterns and interpreting ecological envelopes. Chapter 11 - Population Growth and Regulation Key Concepts 1. Populations can grow rapidly under ideal conditions. 2. Populations have growth limits. 3. Life Tables demonstrate the effects of age, size, and life-history stage on population growth. Definitions to Know Demography: The study of populations, including size, structure, and growth. Growth Rate: The number of new individuals produced per unit time minus the number of deaths. Intrinsic Growth Rate (r): The maximum per capita growth rate of a population under ideal conditions. Doubling Time: The time required for a population to double in size. Growth Models Exponential Growth Model Describes continuous population growth under ideal conditions. Equation: ○ : Future population size. ○ : Current population size. ○ : Intrinsic growth rate. ○ : Time. J-shaped curve: Characteristic shape of exponential growth when graphed. Rate of Growth: The derivative of the equation shows the growth rate at any point in time. Geometric Growth Model  Describes population growth at regular time intervals. Equation: ○ After one interval: ○ After two intervals: ○ General formula: ○ : Ratio of population size at one time to its size in the previous time. Key Points: ○ : Population is increasing. ○ : Population is decreasing. ○ cannot be negative. Comparing Growth Models Exponential and geometric models are mathematically similar:. ○ and : Population is growing. ○ and : Population is constant. ○ and : Population is shrinking. Doubling Time:. Population Regulation Density-Independent Limitations Factors that limit population size regardless of density. Examples: ○ Climatic events: tornadoes, floods, droughts, extreme temperatures. ○ Case Study: Apple thrips in Australia experienced population fluctuations due to seasonal temperature changes. Density-Dependent Limitations Factors that affect population size based on density. ○ Negative Density Dependence: Growth rate decreases as population density increases. Caused by resource limitations (e.g., food, nesting sites, space). High densities increase stress, disease transmission, and predation. ○ Positive Density Dependence (Allee Effect): Growth rate increases with density, often observed in small populations where individuals struggle to find mates or reproduce effectively. Life Tables and Population Growth  Life Table: Summarizes survival and reproductive rates of individuals at different ages, sizes, or stages. ○ Used to calculate population growth rates. Study Tips 1. Understand Key Terms: Be familiar with terms like "intrinsic growth rate" and "density-dependent limitations." 2. Practice Equations: Ensure you can apply exponential and geometric growth formulas. 3. Connect Models to Real-World Examples: Use case studies like apple thrips or other population trends to contextualize theories. 4. Visualize Graphs: Practice interpreting J-shaped and other growth curves. Chapter 12 - Population Dynamics over Time and Space Key Concepts 1. Populations fluctuate naturally over time. 2. Density dependence with time delays can cause populations to be inherently cyclic. 3. Chance events can cause small populations to go extinct. 4. Metapopulations are composed of subpopulations that experience independent dynamics across space. Population Fluctuations All populations experience fluctuations due to: ○ Availability of resources. ○ Predation and competition. ○ Disease, parasites, and climate variations. Random Fluctuations: Unpredictable changes in population size. Cyclic Fluctuations: Regular oscillations in population size over time. ○ Example: Algae in Lake Erie exhibit wide fluctuations (0–7000 cells/m³) due to environmental factors. Small Organisms: Reproduce quickly and respond faster to environmental changes. Large Organisms: Maintain homeostasis better, showing slower population responses. Overshoots and Die-Offs Overshoot: Population grows beyond its carrying capacity (K). ○ Occurs when resources temporarily support a larger population. Die-Off: A sharp decline in population density, often below carrying capacity. ○ Common after an overshoot. Population Cycles: Regular oscillations in population size over long periods. ○ Example: Grouse species in Finland display synchronous cycles. Delayed Density Dependence Definition: Density dependence based on population size at a previous time (lag effect). 1. Example: Moose breed in the fall, but spring resources may not support all offspring born. Mathematical Model: Logistic growth with time delay (τ): Effects of Delayed Density Dependence: 1. Low rτ (< 0.37): Population approaches K without oscillations. 2. Moderate rτ (0.37 – 1.57): Population exhibits damped oscillations. Damped Oscillations: Initial oscillations decline over time. 3. High rτ (> 1.57): Population exhibits a stable limit cycle. Stable Limit Cycle: Persistent oscillations in population size. Extinction and Small Populations Chance Events: Random events (e.g., natural disasters) can disproportionately affect small populations. Demographic Stochasticity: Variation in birth and death rates due to random differences among individuals. Environmental Stochasticity: Variation in population size due to unpredictable environmental changes. Case Study: Small populations of a species can go extinct due to a combination of chance events and environmental pressures. Metapopulations Definition: A group of spatially isolated subpopulations linked by occasional dispersal. Characteristics: 1. Subpopulations may have independent dynamics.  2. Local extinctions can occur, but recolonization by dispersal may stabilize the overall population. Key Factors: 1. Habitat Fragmentation: Creates discrete patches that can support subpopulations. 2. Colonization and Extinction Balance: Stability depends on the rate of colonization exceeding extinction. Study Tips 1. Understand Key Terms: Be familiar with terms like "overshoot," "die-off," and "delayed density dependence." 2. Visualize Dynamics: Practice interpreting graphs of cyclic fluctuations and logistic growth with time delays. 3. Connect to Examples: Use real-world examples (e.g., algae, grouse) to contextualize concepts. 4. Link Concepts: Relate metapopulation dynamics to conservation strategies for fragmented habitats. Chapter 13 - Predation and Herbivory: Key Concepts 1. Predators and herbivores can limit species abundance. 2. Consumer and prey populations often fluctuate in regular cycles. 3. Predation and herbivory favor the evolution of defenses. 4. Predator and prey dynamics can be modeled using mathematical equations. Definitions to Know Mesopredators: Small carnivores that primarily eat herbivores (e.g., coyotes, feral cats). Top Predators: Larger predators that consume both herbivores and other predators (e.g., wolves, sharks). Equilibrium Isocline: The population size of one species at which the population size of another species remains stable. Effects of Predators and Herbivores Predators can drastically reduce prey populations. ○ Example: Caribbean island study showed spider densities were 10x higher on islands without lizard predators. Herbivores can significantly affect plant populations. ○ Example: Leaf beetles reduced invasive Klamath weed populations by 99% in North America. Population Cycles Consumer-Prey Synchrony: ○ Example: Snowshoe hare and Canada lynx populations cycle every 9–10 years, with predator populations lagging. ○ Smaller herbivores (e.g., grouse) often have 4-year cycles. Laboratory Studies: ○ Carl Huffaker's experiments with mites showed that stable cycles require environmental complexity, such as barriers to predator movement. Modeling Predator-Prey Dynamics Lotka-Volterra Model: Explains oscillations in predator and prey populations. Prey Growth: rN−cNPrN - cNPrN−cNP rrr: Prey growth rate, ccc: Capture efficiency, NNN: Number of prey, PPP: Number of predators. Predator Growth: acNP−mPacNP - mPacNP−mP aaa: Conversion efficiency, mmm: Predator mortality rate. Evolution of Defenses 1. Behavioral Defenses: Alarm calling, spatial avoidance, reduced activity. 2. Structural Defenses: Physical traits like spines or tough shells. 3. Chemical Defenses: Toxic compounds deterring predation. 4. Mimicry: ○ Batesian Mimicry: Harmless species mimics a harmful one.  ○ Müllerian Mimicry: Multiple harmful species develop similar warning signals. Study Tips 1. Understand predator-prey relationships and their real-world implications (e.g., effects of removing top predators). 2. Be comfortable with the Lotka-Volterra model equations and equilibrium concepts. 3. Practice explaining examples like the lynx-hare cycles or Huffaker's mite experiments. 4. Familiarize yourself with the types of prey defenses and their evolutionary significance. Chapter 14 - Parasitism and Infectious Diseases: Key Concepts 1. Parasites significantly influence the abundance and dynamics of host populations. 2. Parasite-host interactions depend on the parasite’s infection ability and host defenses. 3. Parasites and hosts co-evolve, leading to offensive and defensive adaptations. Definitions to Know Parasite: An organism living in or on a host, consuming its resources, and causing harm. Pathogen: A parasite that causes infectious diseases. Ectoparasites: Parasites living on the surface of hosts (e.g., ticks, lice, fleas). Endoparasites: Parasites living inside hosts (e.g., viruses, bacteria, fungi). Ectoparasites vs. Endoparasites Factor Ectoparasite Endoparasite s s Exposure to natural enemies High Low Exposure to external environment High Low Movement difficulty (to/from host) Low High Exposure to host immune system Low High Ease of feeding on host Low High Types of Parasites and Pathogens 1. Ectoparasites: ○ Mostly arthropods (ticks, fleas, mites). ○ Examples: Lampreys, nematodes, mistletoe (hemiparasitic plant). 2. Endoparasites: ○ Intracellular: Live within host cells. ○ Intercellular: Live in spaces between host cells. ○ Types include: Prions: Misfolded proteins replicating in host brains (e.g., chronic wasting disease). Viruses: Pathogens like H1N1, H5N1 (bird flu), West Nile virus. Bacteria: Single-celled organisms causing diseases (e.g., anthrax, pneumonia). Fungi: Devastate plants (e.g., Dutch elm disease, chestnut blight). Helminths: Roundworms and flatworms affecting livestock and humans (e.g., hookworms, liver flukes). Notable Parasite Examples Fungal Infection in Carpenter Ants: ○ Fungus forces infected ants to crawl down from trees and die, releasing spores to infect other ants. Dutch Elm Disease: ○ Fungal infection that wiped out American elm trees in the U.S. Hookworms:  ○ Endoparasites feed on blood in the host’s intestines, causing significant harm. Study Tips 1. Understand the differences and trade-offs between ectoparasites and endoparasites. 2. Be familiar with the specific examples of pathogens and the damage they cause. 3. Review co-evolutionary strategies between hosts and parasites. 4. Practice applying the concepts to real-world ecosystems and disease outbreaks. Chapter 15 Competition: Key Concepts 1. Definition of Competition: ○ Occurs when individuals experience limited resources. ○ Includes intraspecific (within species) and interspecific (between species) competition. 2. Influencing Factors: ○ Competition outcomes depend on abiotic conditions, disturbances, and species interactions. 3. Types of Competition: ○ Exploitation Competition: Indirect; individuals deplete shared resources. ○ Interference Competition: Direct; individuals harm others to access resources. ○ Apparent Competition: Occurs when shared enemies increase pressure on both species. The Role of Resources Resource Definition: Anything that increases population growth when more abundant. Non-consumable factors (e.g., temperature) are not resources. Renewable vs. Nonrenewable Resources: ○ Renewable: Regenerate (e.g., sunlight, seeds). ○ Nonrenewable: Fixed supply (e.g., space). Example: Mussels and barnacles compete for space in intertidal zones. Limited space reduces growth and reproduction. Liebig's Law of the Minimum A population’s growth is limited by the scarcest resource. Example: Diatoms compete for silica: Asterionella: Reaches carrying capacity at 1 μM silica. Synedra: Outcompetes Asterionella by surviving at 0.4 μM silica, driving it to extinction. Competitive Interactions 1. Interaction Among Resources: ○ Multiple resources can amplify growth effects. Example: Small balsam plants grew best with both fertilizer and high light. 2. Competitive Exclusion Principle: ○ Two species cannot coexist indefinitely if limited by the same resource. Example: ○ Paramecium aurelia outcompeted P. caudatum when grown together. 3. Related Species Competition: ○ Competition is intense among similar species. ○ Example: Heath bedstraw thrives in acidic soils, while white bedstraw dominates in alkaline soils. 4. Non-Related Species Competition: ○ Distant species can compete for shared resources. Examples: ○ Intertidal zone: Barnacles and algae compete for space. ○ Antarctic ecosystem: Penguins, squid, and whales compete for krill. Important Terms to Remember Negative Density Dependence: Population growth decreases as density increases. Carrying Capacity (K): The maximum population size a resource can sustain. Apparent Competition: Competition through shared predators or parasites. Study Tips 1. Focus on examples to understand competition dynamics. 2. Review interactions among species and how abiotic factors modify competition. 3. Practice applying the competitive exclusion principle to real-world scenarios.  4. Be clear on Leibig’s law and its implications for resource use. Chapter 16 Mutualism: Key Concepts: 1. Mutualism is a positive interaction between two species where both benefit. ○ These interactions can provide water, nutrients, shelter, and help with defense. ○ Mutualisms can impact species distribution, community structure, and ecosystem functioning. 2. Types of Mutualism: ○ Generalists: Species that interact with many different species. ○ Specialists: Species that interact with one or a few closely related species. ○ Obligate Mutualists: Two species that rely on each other for survival. ○ Facultative Mutualists: Species that benefit from the interaction but can survive without it. Examples of Mutualism: Lichens: Fungus provides algae with water, CO2, and nutrients; algae provide carbohydrates through photosynthesis. Corals and Zooxanthellae: Corals give algae a home, and algae provide oxygen and sugars for the coral. Plant Mutualisms: Mycorrhizal Fungi: Help plants obtain water and minerals. ○ Endomycorrhizal Fungi: Hyphae penetrate root cells. ○ Ectomycorrhizal Fungi: Hyphae surround roots but do not enter cells. Rhizobium Bacteria and Legumes: Bacteria convert atmospheric nitrogen into ammonia, which legumes can use. Animal Mutualisms: Termites and Protozoa: Protozoa digest wood particles in termite guts, and termites get nutrients from the protozoa's digestion. Humans and Gut Bacteria: Bacteria help humans digest food in exchange for nutrients. Shrimp and Gobies: Shrimp dig burrows for protection, and gobies warn shrimp of predators in exchange for shelter. Other Examples:  Humans and Honeyguide Birds: The birds lead humans to beehives, and humans collect honey, leaving the larvae and wax for the birds. Concepts to Keep in Mind: Mutualisms can evolve over time and change depending on environmental conditions. Pollination and Seed Dispersal: Many mutualisms facilitate pollination and seed dispersal, which are crucial for plant reproduction. Summary: Focus on the types of mutualisms, examples in plants and animals, and how mutualisms contribute to resource acquisition (water, nutrients, shelter). Understanding the role of mutualism in defense against enemies and its ability to facilitate pollination and seed dispersal will also be essential for your exam. Chapter 17 Community Structure: Key Concepts: 1. Community Structure: A community consists of various species living in a defined area, and its structure is shaped by species composition, abundance, and their interactions. ○ Communities can have distinct or gradual boundaries, depending on the environmental conditions and species tolerance ranges. 2. Diversity in Communities: ○ The diversity of a community is determined by both the number of species and the relative abundance of those species. ○ Species diversity is influenced by factors such as resources, habitat diversity, keystone species, and disturbances. 3. Ecotones: ○ Ecotones are areas where distinct communities meet, often showing sharp changes in species composition due to changes in environmental conditions. ○ Example: The transition between a forest and a grassland is an ecotone. ○ Ecotones typically have high species diversity because they support species from both neighboring communities as well as species specifically adapted to the ecotone. ○ Line-transect surveys can be used to study ecotones by measuring species distribution across a boundary. 4. Interdependence vs. Independence: ○ Interdependent communities: Species in these communities rely on each other for survival, often forming a tightly interconnected system.  ○ Independent communities: Species exist without depending on one another and can experience gradual changes in abundance along environmental gradients. ○ Examples: Interdependence: In harsh conditions (e.g., high elevation), species show interdependence, where removing one species reduces the survival of others. Independence: In less harsh conditions (e.g., low elevation), species may show independence, where removing one species could improve the fitness of others. 5. Community Boundaries and Zonation: ○ Communities can change across landscapes due to varying environmental conditions, leading to zonation (e.g., from desert to oak woodlands to pine forests as you move up a mountain). ○ Zonation can also be observed in aquatic environments (e.g., from freshwater lakes to marine environments). 6. Food Webs: ○ Communities are organized into food webs, where species interact through predator-prey relationships, competition, and symbiosis. 7. Species Distribution: ○ The distribution of species across different environments is influenced by abiotic conditions (e.g., moisture, temperature) and species interactions. 8. Response to Disturbance: ○ Communities respond to disturbances (e.g., fires, storms) with resistance (ability to remain unchanged), resilience (ability to recover), or switching to alternative stable states (transitioning to a different community structure after disturbance). Summary: Focus on understanding how community boundaries work, how species diversity is shaped by environmental factors, and the differences between interdependent and independent communities. Be familiar with ecotones, how they contribute to diversity, and how communities respond to disturbance. Chapter 18 Community Succession: Key Concepts: 1. Succession: ○ Succession is the process by which species composition in a community changes over time.  ○ This can happen over various time scales—from weeks or months (e.g., decomposers on a dead animal) to hundreds of years (e.g., forest succession). ○ Seral stage: Each stage in the process of succession. ○ Pioneer species: The first species to colonize an area, often species that disperse easily (e.g., mosses, grasses). ○ Climax community: The final stage in succession, where the community has reached a stable state, typically with organisms that are adapted to the local conditions (e.g., a forest dominated by oak or beech). 2. Types of Succession: ○ Primary Succession: Occurs in areas that are initially devoid of soil and organisms, such as after a volcanic eruption or on newly formed sand dunes. Pioneer species (e.g., mosses, lichens) colonize bare rock or sand, and over time, they help create soil for other species to establish. ○ Secondary Succession: Occurs in disturbed areas where soil and organic matter still remain (e.g., abandoned fields, forest after a hurricane). The process of recovery can be faster than primary succession because the soil already contains nutrients. 3. Observing Succession: ○ Direct Observation: Observing changes in species composition over time in an area, such as the observation of Krakatau Island after a volcanic eruption in 1883, where researchers documented the colonization of plant species. ○ Chronosequence: A method used when direct observation isn't possible, where scientists study a series of sites at different stages of succession over time. An example of this is Henry Cowles' study of sand dunes around Lake Michigan, where older dunes showed later successional species like trees, compared to younger dunes that had grasses. ○ Pollen Records: By examining preserved pollen in lake sediments, scientists can trace changes in plant species composition over hundreds or thousands of years, helping reconstruct past succession processes. 4. Terrestrial Succession: ○ Seral stages: The different stages a community passes through in its development towards a climax community. The sequence of stages depends on initial conditions, such as soil quality and disturbance history. 5. Animal Succession:  ○ As plant communities change during succession, the habitats available for animals also change. This leads to shifts in the animal community. For example, as vegetation progresses on abandoned agricultural fields in North Carolina, different bird species are found at different stages of succession. 6. Disturbance and Succession: ○ Disturbances (e.g., fires, storms, human activities) can reset the successional process by removing species. The community may return to an earlier seral stage or take a different trajectory depending on the type and severity of the disturbance. ○ Communities may also respond with resistance (remaining stable despite disturbance), resilience (recovering after disturbance), or by switching to alternative stable states (becoming a different community after disturbance). Summary: Succession is the process of community change over time, which can be influenced by disturbances and initial conditions. Understand the difference between primary and secondary succession, and the methods used to observe succession (direct observation, chronosequences, and pollen records). Keep in mind the role of pioneer species and the eventual formation of a climax community. Consider how disturbances influence succession, including the potential for communities to exhibit resistance, resilience, or alternative stable states. Chapter 19, Movement of Energy in Ecosystems, for your exam: Key Concepts: 1. Primary Productivity: ○ Primary productivity is the rate at which solar or chemical energy is captured and converted into chemical bonds through photosynthesis or chemosynthesis. ○ Gross Primary Productivity (GPP): The total rate at which energy is captured and assimilated by producers (plants, algae, etc.) in an ecosystem.  ○ Net Primary Productivity (NPP): The rate at which energy is assimilated and converted into producer biomass (after accounting for the energy used in respiration). NPP = GPP - Respiration. ○ Standing Crop: The amount of biomass of producers present in an ecosystem at a particular moment in time. High primary productivity doesn’t always mean a high standing crop if consumers quickly consume the biomass. 2. Measuring Primary Productivity: ○ Light-Dark Bottle Experiments: Used to measure NPP by monitoring the exchange of CO2. In a sealed chamber: Light bottle: Measures both photosynthesis and respiration. Dark bottle: Measures only respiration. ○ Using 14C (Carbon isotope): A method to track the movement of carbon through plant tissues by measuring the uptake of a rare carbon isotope. ○ In aquatic systems, O2 concentration is often used instead of CO2, since O2 changes during photosynthesis and respiration. Light bottle: Measures O2 increase (photosynthesis and respiration). Dark bottle: Measures O2 decrease (respiration only). ○ Remote Sensing: Uses satellites or airplanes to measure large-scale primary productivity by detecting chlorophyll absorption and reflectance patterns. 3. Secondary Production: ○ Herbivores consume a fraction of the available producer biomass and digest only a portion of the energy they consume. ○ Ingested Energy: The total energy consumed through food. ○ Assimilated Energy: The energy a consumer digests and absorbs (similar to GPP for producers). ○ Respired Energy: The energy used by the consumer for respiration. ○ The remaining energy, after respiration, is used for growth and reproduction, contributing to Net Secondary Productivity (similar to NPP for producers). ○ Net Secondary Productivity: The rate of consumer biomass accumulation in a given area.  4. Energy Flow and Efficiency: ○ The movement of energy through ecosystems is influenced by the efficiency of energy transfer at each trophic level (producers → herbivores → carnivores). ○ Energy Efficiency: Energy is lost at each trophic level primarily through respiration and heat. Typically, only about 10% of the energy from one trophic level is passed on to the next level. Summary: Primary productivity, measured as GPP and NPP, is essential for providing energy to ecosystems. The energy that producers assimilate is available for consumers, with NPP representing the energy available for growth and reproduction. Remote sensing and bottle experiments are tools used to measure productivity across different ecosystems. Secondary production focuses on how consumers use the energy they ingest for growth and reproduction, contributing to biomass accumulation. The efficiency of energy flow through ecosystems impacts the overall structure and functioning of food webs. Chapter 20 Movement of Elements in Ecosystems: Key Concepts: 1. The Hydrologic Cycle: ○ Moves water through ecosystems and the atmosphere, involving processes like evaporation, transpiration, and precipitation. ○ Water is crucial in many chemical transformations within ecosystems. 2. The Carbon Cycle: ○ Tied closely to the movement of energy in ecosystems. Carbon moves through living and nonliving components of ecosystems. 3. The Phosphorus Cycle: ○ Moves phosphorus between land and water. 4. Nutrient Regeneration: ○ In terrestrial ecosystems, nutrients regenerate in the soil. ○ In aquatic ecosystems, nutrients regenerate in sediments. 5. The Nitrogen Cycle: ○ Nitrogen moves through ecosystems in various forms. The Hydrologic Cycle:  The hydrologic cycle describes the movement of water through ecosystems and the atmosphere. It includes: ○ Evaporation: Water turning into vapor from water bodies. ○ Transpiration: Water moving from plants to the atmosphere. ○ Precipitation: Water falling to the Earth in the form of rain, snow, etc. Global Water Distribution: ○ 97% of water is in the oceans. ○ The rest is in lakes, streams, rivers, wetlands, aquifers, and soil. Balance of Water: ○ Precipitation exceeds evaporation on land (terrestrial ecosystems). ○ In aquatic systems, evaporation exceeds precipitation. ○ Excess water on land flows as runoff into aquatic systems. The Carbon Cycle: Carbon moves through the atmosphere, oceans, and terrestrial ecosystems. The largest carbon compartment is in sedimented carbonates. Human Impact: ○ Fossil Fuel Combustion: Over the past two centuries, the burning of coal, oil, and natural gas has increased, releasing CO2 into the atmosphere. ○ Mauna Loa CO2 Data: From 1958 to 2012, CO2 in the atmosphere increased by 25%. ○ Ice Cores: Scientists use ice cores to study CO2 concentrations trapped in air bubbles in ice, providing data on CO2 from hundreds of thousands of years ago. Global Warming: ○ CO2 is a greenhouse gas that absorbs infrared radiation, contributing to global warming. ○ The mean temperature of Earth has increased by 0.8°C since the 1880s, with some regions warming by 4°C. Permafrost Thawing: ○ In high-latitude regions, warming causes peat (dead plant material) to thaw, releasing methane gas, exacerbating global warming. The Nitrogen Cycle: Nitrogen Fixation: The process of converting atmospheric nitrogen (N2) into forms usable by producers (plants), like ammonia (NH3), which turns into ammonium (NH4+), and nitrate (NO3–). ○ Biotic Nitrogen Fixation: Occurs in species like cyanobacteria, free-living bacteria (e.g., Azotobacter), and in bacteria forming mutualisms with plants (e.g., Rhizobium).  ○ Abiotic Nitrogen Fixation: Occurs due to natural processes like lightning, wildfires, or combustion of fossil fuels. Summary: The hydrologic cycle moves water through ecosystems and is essential for chemical processes. The carbon cycle is integral to energy movement, and human activities, like burning fossil fuels, have significantly impacted it. The phosphorus cycle moves phosphorus between land and water. Nitrogen fixation is crucial for converting atmospheric nitrogen into usable forms for plants. Human activities continue to alter the natural balance of these cycles, particularly through the release of greenhouse gases. Chapter 21 & 22 Landscape Ecology and Global Biodiversity: Key Concepts: 1. Landscape Ecology: Examines ecological patterns and processes at large spatial scales. 2. Species-Area Relationship: The number of species increases with area. 3. Global Species Distribution: Influenced by Earth’s history. 4. Equilibrium Theory of Island Biogeography: Considers both area and isolation. Landscape Ecology: Definition: Landscape ecology studies how the spatial arrangement of habitats at various scales influences individuals, populations, communities, and ecosystems. Causes of Habitat Heterogeneity: ○ Legacy Effects: Long-lasting influence of historical processes (e.g., eskers formed by glaciers). ○ Natural Forces: Events like tornadoes, hurricanes, floods, and fires contribute to habitat diversity. ○ Human Activity: Human actions, such as construction and deforestation, also cause habitat heterogeneity. Humans act as "ecosystem engineers." Habitat Heterogeneity and Species Diversity: 1. Local (Alpha) Diversity: Number of species in a small, homogeneous area. ○ Example: 17 bird species in a single stream in Vermont. 2. Regional (Gamma) Diversity: Number of species across a larger geographic area. ○ Example: 101 bird species across 27 streams in Vermont. 3. Beta Diversity: Number of species that differ between two habitats. ○ Example: If Stream A has 5 species not in Stream B, and Stream B has 3 species not in Stream A, beta diversity is 8. Species-Area Relationship: Species-Area Curve: As the area (A) increases, the number of species (S) also increases. ○ The equation for this relationship is: S = cA^z Taking the logarithm of both sides gives a straight line on a log-log plot: log(S) = log(c) + z log(A) ○ Where c and z are constants. Examples: ○ Robert MacArthur and E. O. Wilson observed increased species richness on Caribbean islands as island area increased. ○ Across different organisms, the slope (z) of the relationship between species richness and area ranges from 0.20 to 0.35. Theory of Island Biogeography: MacArthur and Wilson’s Findings: ○ Species richness increases with island area. ○ Islands closer to the mainland have higher species richness, as they are more easily colonized. Equilibrium Theory: Proposes that the number of species on an island reflects a balance between the colonization of new species and the extinction of existing ones. ○ Colonization: New species colonize the island from nearby habitats (e.g., mainland). ○ Extinction: As more species colonize, competition and negative interactions increase, leading to species extinctions. Equilibrium Point: There is a continuous turnover of species at equilibrium, but the total number of species remains stable, although species composition fluctuates over time. Summary: Landscape ecology explores how large-scale spatial arrangements of habitats impact ecosystems. Species-area relationships show that species richness increases with area and is influenced by both the area and isolation of habitats. Island biogeography explains how the number of species on an island is determined by a balance between colonization and extinction, with an equilibrium point of species richness.