u8 ecology

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### **🌱 Levels of Organization & Energy Flow**

**Organism** – A single living individual.

**Population** – A group of individuals of the same species living in the same area.

**Community** – All the different populations interacting in an area.

**Ecosystem** – The community plus abiotic (non-living) factors in an area.

**Biome** – A large ecological region with similar climate and organisms.

**Biosphere** – All ecosystems on Earth, including land, water, and air.

**Abiotic Factors** – Non-living parts of an environment (e.g., sunlight, water, temperature).

**Biotic Factors** – Living parts of an environment (e.g., plants, animals, bacteria).

**Trophic Level** – A step in a food chain or web (e.g., producer, primary consumer).

**Autotroph (Producer)** – An organism that makes its own food via photosynthesis or chemosynthesis.

**Heterotroph (Consumer)** – An organism that eats other organisms for energy.

**Food Chain** – A linear flow of energy through an ecosystem.

**Food Web** – A complex network of interconnected food chains.

**Primary Productivity** – The rate at which producers convert sunlight into energy.

- **Gross Primary Productivity (GPP)** – Total energy produced.

- **Net Primary Productivity (NPP)** – Energy left after producers use some for respiration.

**Energy Pyramid** – A diagram showing energy loss at each trophic level (10% Rule: only 10% of energy moves up).

**Biomass** – The total mass of living organisms in a given area.

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### **🌿 Biogeochemical Cycles**

**Water Cycle** – The continuous movement of water through evaporation, condensation, precipitation, and runoff.

**Carbon Cycle** – Movement of carbon through respiration, photosynthesis, fossil fuels, and the atmosphere.

**Nitrogen Cycle** – Movement of nitrogen through nitrogen fixation, nitrification, and denitrification.

**Phosphorus Cycle** – The cycling of phosphorus between rocks, soil, water, and organisms.

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### **🌾 Population Ecology**

**Population Density** – Number of individuals per unit area.

**Dispersion Patterns** – The way individuals are spaced in an area:

- **Clumped** (most common, grouped around resources)

- **Uniform** (evenly spaced, seen in territorial species)

- **Random** (unpredictable spacing)

**Carrying Capacity (K)** – The maximum population size an environment can support.

**Logistic Growth (S-Curve)** – Population growth that slows as it reaches carrying capacity.

**Exponential Growth (J-Curve)** – Rapid population increase under ideal conditions.

**Density-Dependent Factors** – Factors that affect populations more as they grow (e.g., competition, predation, disease).

**Density-Independent Factors** – Factors that affect populations regardless of size (e.g., natural disasters, climate).

**r-Selected Species** – Short lifespan, high reproduction rate, little parental care (e.g., insects, rodents).

**K-Selected Species** – Long lifespan, few offspring, high parental care (e.g., elephants, humans).

**Survivorship Curves:**

- **Type I** – High survival in early/mid-life, drops in old age (e.g., humans, elephants).

- **Type II** – Constant mortality rate (e.g., birds, squirrels).

- **Type III** – High mortality early, few survive to adulthood (e.g., fish, plants).

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### **🌍 Community Ecology**

**Niche** – An organism’s role in its environment (e.g., what it eats, where it lives).

- **Fundamental Niche** – The full range of conditions a species could use.

- **Realized Niche** – The actual conditions a species uses due to competition.

**Competitive Exclusion Principle** – No two species can occupy the same niche in the same habitat.

**Resource Partitioning** – Species use resources differently to reduce competition.

**Symbiotic Relationships:**

- **Mutualism (+/+)** – Both species benefit (e.g., bees and flowers).

- **Commensalism (+/0)** – One species benefits, the other is unaffected (e.g., barnacles on whales).

- **Parasitism (+/-)** – One species benefits, the other is harmed (e.g., ticks on dogs).

**Keystone Species** – A species that has a major impact on its ecosystem (e.g., wolves in Yellowstone).

**Invasive Species** – Non-native species that disrupt ecosystems (e.g., zebra mussels, kudzu).

**Predation** – One organism (predator) kills and eats another (prey).

**Herbivory** – An organism eats plants.

**Ecological Succession** – Natural process of ecosystem change over time.

- **Primary Succession** – Starts on bare rock (no soil), e.g., volcanic island formation.

- **Secondary Succession** – Happens after a disturbance (e.g., forest fire).

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### **🔥 Ecosystem Stability & Human Impact**

**Biodiversity** – The variety of life in an ecosystem.

**Ecosystem Services** – Benefits ecosystems provide (e.g., pollination, water purification).

**Climate Change** – Long-term changes in global temperatures and weather patterns.

**Deforestation** – Large-scale removal of trees, affecting ecosystems and climate.

**Biomagnification** – The increase in toxic substance concentration at higher trophic levels (e.g., mercury in fish).

**Eutrophication** – Excess nutrients in water cause algae blooms and dead zones.

**Habitat Fragmentation** – The breaking up of ecosystems due to human activities.

**Conservation Biology** – The study of protecting and restoring biodiversity.

**Ecological Footprint** – The impact of human activities on the environment.