Ecology Study Guide Notes

What is Ecology?

• Definition: Study of interactions among organisms and their environment.

• Branches: Includes population ecology, community ecology, ecosystem ecology, and biosphere ecology.

What is an Ecosystem?

• Components: Biotic (living organisms) and abiotic (non-living things) factors.

• Energy Flow: Energy enters (through sunlight for autotrophs) and flows through an ecosystem.

Biosphere

• Definition: The global sum of all ecosystems; zone of life on Earth.

• Extent: Encompasses land, water, and the atmosphere, where life exists.

Symbiosis

• Definition: Interaction between two different organisms living in close physical proximity.

• Types:

  • Mutualism: Both species benefit (e.g., bees pollinating flowers).

  • Parasitism: One organism benefits at the expense of another (e.g., ticks on mammals).

  • Commensalism: One organism benefits while the other is neither helped nor harmed (e.g., barnacles on whales).

What is a Niche?

• Definition: The role or function of a species within its ecosystem, including its habitat, resource use, and interactions with other species.

What is a Habitat?

• Definition: The natural environment in which a species or community lives.

• Characteristics: Includes climate, soil type, vegetation, and available resources.

Species, Populations, Communities

• Species: A group of similar individuals that can reproduce and exchange genes.

• Population: A group of individuals of the same species living in a specific area.

• Community: All interacting populations of different species within a particular area.

Autotrophs and Heterotrophs

• Autotrophs: Organisms that produce their own food (e.g., plants through photosynthesis).

• Heterotrophs: Organisms that consume other organisms for food (e.g., animals).

Producers, Consumers, Detritivores, and Decomposers

• Producers: Autotrophs; first trophic level (e.g., plants).

• Consumers: Organisms that rely on others for energy; categorized into primary, secondary, and tertiary consumers.

• Detritivores and Decomposers: Break down dead organic material, recycling nutrients back into the ecosystem (e.g., earthworms, fungi).

What are Biomes?

• Definition: Large ecological areas with distinct climates, plants, and animals.

• Examples: Deserts, forests, grasslands, tundra.

The Main Terrestrial Biomes

• Tropical Rainforest: High biodiversity, warm, and wet.

• Desert: Low precipitation, extreme temperatures.

• Temperate Deciduous Forest: Four seasons, trees that lose leaves in winter.

• Grasslands: Dominated by grasses, few trees.

• Tundra: Cold, treeless, low biodiversity.

The Main Aquatic Ecosystems

• Freshwater: Lakes, rivers, streams.

• Marine: Oceans, coral reefs, estuaries.

  • Photic Areas: Regions of light penetration.

  • Aphotic Areas: Regions without light.

What is Population Density?

• Definition: The number of individuals per unit area or volume.

Patterns of Population Growth

• Exponential Growth: Rapid increase when resources are abundant; represented by the equation: N(t) = N_0 e^{rt}.

• Logistic Growth: Growth that levels off as population reaches carrying capacity

• Carrying Capacity: The maximum population size that an environment can sustain, influenced by availability of resources such as food, space, and water.

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What is Carrying Capacity?

• Definition: The maximum number of individuals of a species that an environment can support sustainably.

Main Nutrient Cycles

• Carbon Cycle: Movement of carbon among the biosphere, atmosphere, oceans, and geosphere.

• Nitrogen Cycle: Conversion of nitrogen into different chemical forms; includes nitrogen fixation: process by which certain bacteria convert nitrogen gas into ammonia.

Renewable and Non-Renewable Resources

• Renewable: Resources that can be replenished naturally (e.g., solar energy, wind).

• Non-Renewable: Resources that do not replenish quickly (e.g., fossil fuels, minerals).

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Biomagnification

• Definition: The increasing concentration of toxic substances in the tissues of organisms at successively higher levels in a food chain.

Biotic and Non-Biotic Factors

• Biotic: Living components of an ecosystem (e.g., plants, animals).

• Non-Biotic: Non-living components (e.g., water, temperature, soil).

Predation and Competition

• Predation: An interaction where one organism (predator) hunts another (prey).

• Competition: Interaction between organisms vying for the same resources in an ecosystem.

Pyramids of Biomass, Numbers, and Energy

• Biomass Pyramid: Representation of total mass of living matter at each trophic level.

• Pyramid of Numbers: The number of individual organisms at each trophic level.

• Pyramid of Energy: Energy transfer between trophic levels, generally decreases as you move up the pyramid.

HIPPO Acronym

• H: Habitat destruction

• I: Invasive species

• P: Pollution

• P: Population growth

• O: Overharvesting

Habitat Destruction and Fragmentation

• Definition: The process where natural habitat is destroyed or divided due to human activities (e.g., urban development).

Invasive Species

• Definition: Non-native species that spread widely and cause harm (e.g., zebra mussels, kudzu).

Main Sources of Pollution

• Air Pollution: Emissions from factories, vehicles.

• Water Pollution: Industrial discharge, agricultural runoff.

• Soil Pollution: Use of pesticides, littering.

Population and Overharvesting

• Relationship: Overharvesting can lead to population declines and extinction of species.

What is Ozone?

• Definition: A molecule made of three oxygen atoms (O₃) in the Earth's stratosphere, protecting the planet from UV radiation.

• Issue: Ozone depletion caused by chlorofluorocarbons (CFCs) and other chemicals.

What is Global Warming and the Greenhouse Effect?

• Global Warming: Increase in Earth's average surface temperature due to rising levels of greenhouse gases.

• Greenhouse Effect: Process by which certain gases trap heat in the atmosphere, maintaining Earth's temperature.

Most Damaging Greenhouse Gases

• Carbon Dioxide (CO₂): Major contributor from burning fossil fuels.

• Methane (CH₄): Emitted during fossil fuel extraction, agriculture, and landfills.

• Nitrous Oxide (N₂O): Released from fertilizers and other industrial activities.

What is Climate Change?

• Definition: Long-term alteration of temperature and typical weather patterns in a place.

• Causes: Primarily linked to human activity, particularly fossil fuel consumption.

Mitigating Effects of Climate Change

• Strategies: Reducing greenhouse gas emissions, switching to renewable energy sources, increasing energy efficiency, reforestation, and promoting sustainable practices.