Ecology AI Sheets Summary

Notes on Populations (2.1) - Individuals, Populations, Communities, and Ecosystems

Overview

This lesson focuses on the fundamental concepts of ecology, including the relationships between individuals, populations, communities, and ecosystems. It covers various aspects of population biology, ecological niches, and the factors influencing species distribution.

Lesson Breakdown

1. Identification of Species

   • Biosphere: Represents all parts of Earth where life exists, composed of individuals, populations, communities, and ecosystems.

   • Species Definition: A species is a group of organisms capable of interbreeding and producing fertile offspring.

   • Classification: Organisms are classified to manage the immense diversity of species. The classification system uses a two-part name: genus (capitalized) and species (lowercase), both italicized or underlined.

   • Identification Tools: Taxonomists use tools like dichotomous keys and DNA surveys to identify species. Practical applications include using apps like Plantnet for plant identification.

2. Abiotic Factors

   • Distribution Factors: Population distribution is influenced by abiotic (non-living) and biotic (living) factors.

   • Examples of Abiotic Factors: Temperature, sunlight, pH, salinity, dissolved oxygen, and soil texture affect species distributions. Skills include measuring these factors in ecosystems.

3. Populations

   • Niche: An ecological niche encompasses the biotic and abiotic conditions necessary for a species' survival, including food acquisition.

   • Population Interactions: Populations interact through herbivory, predation, parasitism, mutualism, disease, and competition, influencing population dynamics.

   • Carrying Capacity: This is the maximum population size an environment can sustain, determined by resource availability.

   • Regulation of Population Size: Population size is influenced by density-dependent factors (e.g., competition, predation) and negative feedback mechanisms.

   • Population Growth: Growth can be exponential (J-curve) or limited by carrying capacity (S-curve). Examples include reindeer populations on St. Matthew Island.

4. Quadrat Sampling

   • Estimation Methods: Population abundance can be estimated using random, systematic, or transect sampling.

   • Quadrat Sampling: This method estimates the percentage cover and frequency of non-mobile organisms, providing insights into population density.

5. Lincoln Index

   • Capture-Recapture Method: This method estimates population size for mobile organisms using the formula: Population size = (M × N) / R, where M is the number of initially marked individuals, N is the total recaptured, and R is the number of marked individuals recaptured.

6. Community and Sustainability

   • Community Definition: A community consists of interacting populations within an ecosystem.

   • Habitat: The habitat is the specific location where a community or species lives, encompassing geographical and physical conditions.

   • Ecosystem Dynamics: Ecosystems are open systems where energy and matter flow in and out.

   • Sustainability: Ecosystems maintain a balance between inputs and outputs, crucial for long-term stability.

   • Human Impact: Human activities can disrupt ecosystem stability, leading to tipping points and potential collapse.

   • Keystone Species: These species play a critical role in maintaining community structure; their removal can lead to significant ecological changes.

   • Planetary Boundaries: Changes to biosphere integrity due to human activity have crossed critical thresholds, necessitating efforts to reverse these impacts.

Conclusion

Understanding the interactions between individuals, populations, communities, and ecosystems is essential for studying ecology and addressing environmental challenges. This lesson provides foundational knowledge for further exploration of ecological principles and conservation efforts.

Notes on EcoCycles: Dynamics & Biomass (2.2 & 2.3)

1. Laws of Thermodynamics

• 2.2.1 Ecosystems and Energy: Ecosystems are open systems where energy and matter are exchanged.

• 2.2.2 First Law of Thermodynamics: Energy can be transformed but not created or destroyed; it flows through ecosystems in various forms (e.g., light to chemical, chemical to heat).

• 2.2.3 Photosynthesis and Cellular Respiration: These processes transform energy and matter, with photosynthesis converting light energy into chemical energy, and respiration breaking down glucose to release energy.

• 2.2.4 Photosynthesis: Converts light energy to chemical energy in glucose, which can be stored as biomass by autotrophs.

• 2.2.5 Producers: Typically plants, algae, and photosynthetic bacteria that produce their own food through photosynthesis.

• 2.2.6 Cellular Respiration: Releases energy from glucose, which is used for cellular activities.

• 2.2.7 Heat Generation: Some energy from cellular respiration is lost as heat, which cannot be converted back into chemical energy.

• 2.2.8 Second Law of Thermodynamics: Energy transformations are inefficient, with significant losses occurring during cellular respiration.

2. Food Chains and Food Webs

• 2.2.9 Consumers: Obtain chemical energy from organic compounds through various strategies (e.g., herbivores, predators, decomposers).

• 2.2.10 Producers in Food Chains: Producers are at the start of food chains, with energy flowing from them to consumers.

• 2.2.11 Trophic Levels: Stages in a food chain where carbon compounds and energy are passed from one organism to another.

• 2.2.12 Energy Losses: Not all food is consumed or absorbed; energy is lost at each trophic level, leading to inefficiencies.

• 2.2.14 Trophic Level Limitations: Energy losses limit the number of trophic levels in ecosystems, with typically 10% of energy available to the next level.

• 2.2.15 Food Web Complexity: Food webs illustrate the complex feeding relationships in ecosystems, with species potentially occupying multiple trophic levels.

3. Productivity and Pyramids

• 2.2.13 Gross and Net Productivity: Gross productivity is the total biomass gain, while net productivity is what remains after losses from respiration.

• 2.2.16 Measuring Biomass: Biomass can be measured by collecting and drying samples, with energy content assessed through combustion.

• 2.2.17 Ecological Pyramids: Represent relative numbers, biomass, or energy at different trophic levels, showing variations in shape based on ecosystem dynamics.

4. Toxins in Ecosystems

• 2.2.18 Non-biodegradable Pollutants: Pollutants like PCBs and DDT cause bioaccumulation and biomagnification in ecosystems.

• 2.2.19 Microplastics: Non-biodegradable pollutants absorbed by microplastics can increase their transmission through food chains.

• 2.2.20 Human Impact: Activities such as fossil fuel burning and deforestation disrupt energy flows and matter transfers in ecosystems.

• 2.2.21 Autotrophs and Heterotrophs: Autotrophs synthesize carbon compounds from inorganic sources, while heterotrophs obtain them from other organisms.

5. Biogeochemical Cycles

• 2.3.1 Biogeochemical Cycles: Ensure the availability of chemical elements to living organisms, with human impacts affecting ecosystem sustainability.

• 2.3.2 Stores, Sinks, and Sources: Stores are in equilibrium, sinks indicate accumulation, and sources indicate release of elements.

• 2.3.3 Organic and Inorganic Carbon Stores: Organisms and fossil fuels contain organic carbon, while inorganic stores are found in the atmosphere and oceans.

• 2.3.4 Carbon Flow: Carbon flows through ecosystems via photosynthesis, respiration, and decomposition.

• 2.3.5 Carbon Sequestration: The process of capturing atmospheric CO2 and storing it in solid or liquid forms.

• 2.3.6 Ecosystem Roles: Ecosystems can act as carbon stores, sinks, or sources depending on the balance of photosynthesis and respiration.

• 2.3.7 Fossil Fuels: Formed from ancient ecosystems, they act as carbon stores with long residence times.

6. Agriculture and Ocean Acidification

• 2.3.8 Agricultural Systems: Can act as carbon stores, sources, or sinks based on farming techniques.

• 2.3.9 Ocean Carbon Absorption: Oceans absorb CO2 but cannot keep pace with human emissions.

• 2.3.10 Ocean Acidification: Increased CO2 levels lead to lower pH, affecting marine life.

• 2.3.11 Mitigation Measures: Include low-carbon technologies, reducing fossil fuel use, and enhancing carbon sequestration.

Notes on Climate and Biomes (2.4) and Zonation, Succession, and Change in Ecosystems (2.5)

2.4 Climate and Biomes

1. Weather and Climate

   • Climate vs. Weather: Climate describes atmospheric conditions over long periods (approximately 30 years), while weather refers to short-term atmospheric conditions, including temperature, humidity, air pressure, and wind speed.

   • Biomes: A biome is a group of comparable ecosystems that develop under similar climatic conditions. Major influences on the distribution of terrestrial biomes include precipitation, temperature, and insolation.

   • Abiotic Factors: These are determinants of terrestrial biome distribution. For any given temperature and rainfall pattern, a specific ecosystem type is likely to develop. Skills include creating climate graphs to show annual precipitation and average temperature for different biomes.

2. Exploring Biomes

   • Categorization of Biomes: Biomes can be categorized into groups such as freshwater, marine, forest, grassland, desert, and tundra, each with characteristic abiotic limiting factors, productivity, and biodiversity.

   • Global Warming: This phenomenon is leading to changing climates and shifts in biomes, with a general trend of biomes moving poleward and to higher altitudes.

3. Atmosphere, Oceans, and Climate

   • Tricellular Model: This model explains atmospheric circulation and the distribution of precipitation and temperature at different latitudes, influencing the structure and productivity of terrestrial biomes. It includes three distinct cells: the Hadley cell, the Ferrel cell, and the polar cell.

   • Ocean Currents: Oceans absorb solar radiation, and ocean currents distribute heat around the world, impacting climate and biomes.

2.5 Zonation, Succession, and Change in Ecosystems

1. Zonation

   • Definition: Zonation refers to changes in community composition along an environmental gradient, influenced by factors such as elevation, latitude, tidal level, soil horizons, or distance from water sources.

   • Transects: Transects can be used to measure biotic and abiotic factors along an environmental gradient to determine variables affecting species distribution. Skills include investigating zonation using transect sampling techniques and creating kite diagrams to show distribution.

2. Primary Succession

   • Definition: Succession is the replacement of one community by another over time due to changes in biotic and abiotic variables. Primary succession occurs on newly formed substratum where there is no soil or pre-existing community (e.g., volcanic rock).

   • Seral Communities: Each seral community in succession causes changes in environmental conditions that allow the next community to replace it through competition until a stable climax community is reached. Examples include mosses initiating soil formation.

3. Secondary Succession and Stability

   • Definition: Secondary succession occurs on bare soil where there has been a pre-existing community, such as after a fire or agricultural cessation.

   • Changes During Succession: Energy flow, productivity, species diversity, soil depth, and nutrient cycling change over time during succession. Data analysis can reveal reasons for these changes.

   • Ecosystem Resilience: An ecosystem's capacity to tolerate disturbances and maintain equilibrium depends on its diversity and resilience. Succession increases diversity, which contributes to resilience and stability, although human interference can reduce these qualities.

Conclusion

Understanding climate, biomes, zonation, and succession is crucial for studying ecological dynamics and the impacts of environmental changes. These concepts provide a framework for analyzing how ecosystems function and respond to both natural and anthropogenic influences.