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🌍 Biodiversity
The variety of life across genetic, species, and ecosystem levels.
🧬 Genetic Diversity
The range of genetic traits within a species.
🦁 Species Diversity
The number of species in an area.
🏞 Ecosystem Diversity
The variety of habitats in an area.
🌱 Ecosystems with high biodiversity have:
✅ Abundant natural resources
✅ Large genetic diversity
✅ Complex food webs with diverse niches
✅ Large numbers of different species
🔄 Importance: Biodiversity maintains environmental balance and stability.
📈 Diversity Increasers:
✔ Diverse habitats
✔ Evolution
✔ Middle stages of succession
✔ High diversity at trophic levels
📉 Diversity Decreasers:
❌ Habitat disturbance
❌ Environmental stress
❌ Geographic isolation
❌ Introduction of non-native species
Anthropogenic Activities That Reduce Biodiversity
🔥 Burning Fossil Fuels: Produces acid rain, which alters water pH and harms aquatic life.
🌲 Deforestation: Reduces habitat quality and eliminates species.
🚜 Industrial Agriculture: Monoculture decreases biodiversity and depletes soil nutrients.
🎣 Overfishing: Threatens keystone species and disrupts entire food chains.
🐜 Pesticide Use: Kills both pests and beneficial organisms.
🌱 Genetically Modified Organisms (GMOs): Reduce genetic variation and limit adaptation to environmental change.
🚰 Water Pollution: Low oxygen and high nutrient levels harm aquatic species.
Population Bottleneck
💥 Population Bottleneck: A drastic population reduction due to environmental disaster.
🧬 Effect: Leads to low genetic diversity, making species more vulnerable.
🔢 Minimum Viable Population Size: The smallest population needed to survive without going extinct.
🦝 Generalist Species:
✔ Live in varied environments.
✔ Have diverse diets.
✔ Example: Raccoons, which eat a wide variety of foods.
🐼 Specialist Species:
❌ Need specific habitats and limited diets.
❌ More vulnerable to habitat destruction.
❌ Example: Giant Pandas, which rely almost entirely on bamboo.
🌿 Species Richness
The number of different species in a community.
🌏 Higher richness occurs when species come from diverse habitats rather than similar environments.
🎣 Sustainable Fisheries & Aquaculture
Support recreational services and healthy aquatic ecosystems.
🏞 Recreational Fishing
Depends on balanced aquatic ecosystems.
🌿 Ecosystems provide diverse materials and products essential for survival.
🐮 Livestock Contributions:
✔ Wool for fiber
✔ Meat & Milk for food
✔ Other raw materials for human use
🦠 Natural Pest Control:
✔ Maintains pest populations through natural predators.
✔ Keeps food prices lower by reducing crop loss.
✔ Lowers the need for chemical pesticides.
🦅 How It Works: Predators, parasites, and prey defense mechanisms help regulate populations.🌱 Soil Formation & Fertility:
✔ Helps create new soil and restore nutrients.
✔ Allows for greater crop yields to feed more people.
✔ Reduces the need for synthetic fertilizers.
🏝 Island
A suitable habitat surrounded by an unsuitable environment.
🌍 Island Biogeography
Studies factors that affect species diversity in isolated ecosystems.
Theory of Island Biogeography
📊 Key Idea: The number of species on an island depends on immigration & extinction rates.
🚢 Closer islands: Easier for migrating species to reach.
🌿 Larger islands: Support more biodiversity & have lower extinction rates.
Factors Affecting Island Biogeography
📏 Degree of Isolation: Distance from the mainland or other islands.
🛣 Habitat Fragmentation:
✔ Caused by roads, logging, development.
✔ Leads to the edge effect (more exposure to outside threats).
🌡 Climate & Habitat Suitability: Determines which species can survive.
🌱 Initial & Current Species Composition: Affects future biodiversity.
🏗 Human Activity: Can disrupt ecosystems and alter migration patterns.
🌊 Ocean Currents: Affect species movement & ecosystem conditions.
Important Points for Islands
🦜 Closer islands have higher biodiversity due to easier migration.
🏗 Habitat fragmentation is the main threat to terrestrial biodiversity.
📉 Larger islands have:
✔ More species due to bigger land area.
✔ Higher populations that reduce extinction rates.
🌎 Island Biogeography helps predict biodiversity changes in fragmented habitats on continents.
Law of Tolerance
The existence, abundance, and distribution of species depend on their ability to tolerate environmental conditions.
🌡 Tolerance Range
Each species has minimum, maximum, and optimum levels for survival.
Factors Affecting Ecological Tolerance
🌱 Biotic Factors: Competition, predation, disease.
🌎 Abiotic Factors: Temperature, pH, water availability, sunlight.
⛰ Climatic & Topographic Factors: Elevation, weather patterns, geographic location.
📉 If conditions exceed an organism’s tolerance:
✔ Populations decline.
✔ Species may migrate or adapt.
✔ In extreme cases, extinction occurs.
🌍 Ecosystems
🌍 Ecosystems: Communities of organisms that interact and change over time.
⚡ Natural Disruptions
Sudden events that determine which species survive and which go extinct.
Flooding & Its Effects
🌊 Destroys wildlife and food sources.
🌱 Soil erosion occurs as plant roots are washed away.
💨 Saturated soils drown plant roots due to lack of oxygen.
🏡 Burrows, nests, and dens are destroyed.
⚡ Floodplain species benefit from nutrient-rich sediments.
Volcanic Eruptions
🌋 Kills wildlife & plants but creates rich soil over time.
💨 Contributes to Earth's atmosphere and water formation.
❄ Sulfur gases cool the troposphere by 2–3°C.
Wildfires
🔥 Destroys plants & animals but also benefits ecosystems.
☀ Clears dead vegetation, allowing new growth.
🌱 Ash and charcoal enrich the soil.
🌿 Some plants rely on fire for reproduction.
Types of Earth System Processes
🔄 Episodic: Irregular events (e.g., El Niño, La Niña).
🔁 Periodic: Regular cycles (e.g., Tides).
⚠ Random: Unpredictable events (e.g., Meteorite impacts).
Sea Level Changes
🌡 Rising due to global warming (melting ice caps & thermal expansion).
🌊 ~30% due to glacier/ice melt.
🔥 ~30% due to ocean water expansion.
🏝 ~40% due to coastal land subsidence.
Wildlife Migrations
🚀 Escape harsh weather (e.g., migrate to warmer areas for breeding).
🌪 Flee natural disasters (e.g., wildfires, floods).
🍽 Find food resources in new habitats.
🔄 Adaptation
🔄 Adaptation: The biological process where organisms adjust to new environments or changes in their habitat.
Types of Adaptations
🧠 Behavioral Adaptation: Instincts, mating behavior, or vocalizations.
🔥 Physiological Adaptation: Temperature control, digestion methods.
🦔 Structural Adaptation: Physical traits like body coverings.
Short-Term Adaptations
⏳ Temporary response to environmental changes.
🧬 Does not alter DNA and is not inherited.
❌ Not part of evolution.
Long-Term Adaptations & Evolution
🦠 Involves DNA changes over time.
🌿 Occurs due to natural selection.
🔁 Key driver of evolution in species.
🌱 Ecological Succession
A gradual and orderly process where ecosystems change over time due to species interactions and disturbances.
Key Terms in Succession
🌿 Facilitation: One species modifies the environment to benefit another species.
🚫 Inhibition: One species modifies the environment, making it unsuitable for another species.
⚖ Tolerance: Some species are not affected by the presence of others.
🌱 Pioneer Species: Early successional plants and animals that are generalists.
🔵 Primary Succession:
Occurs on barren land (no previous life).
Takes 1,000+ years.
No soil at the start.
Pioneer species arrive from outside.
🟢 Secondary Succession:
Occurs where life once existed but was disturbed.
Takes 50–200 years.
Soil is already present.
Pioneer species develop from past occupants & migration.
Changes During Succession
📈 Species richness increases, peaking at the climax community.
🌍 Energy flow becomes more complex over time.
🌱 Soil depth, nutrients, and water retention improve.
🌿 Net primary productivity (NPP) rises, then stabilizes.
🦇 Keystone species
A species critical to ecosystem balance—its extinction would cause major disruptions.
Examples:
Bats 🦇 pollinate rainforests & disperse seeds.
Grizzly bears 🐻 transfer nutrients to forests.
Sea stars ⭐ keep mussel & sea urchin populations in check.
🧐 Indicator species
Organisms that signal environmental health.
Examples:
Caddisflies & mayflies 🦟 indicate high oxygen levels in water.
Lichens 🍃 signal air pollution.
Mollusks 🐚 indicate water pollution.
Mosses 🌿 show acidic soil conditions.
