Ecology Study Guide Notes - Honors

Organization of Ecological Terms

  • Organism: An individual life form, capable of carrying out basic life functions.

    • Example: A single oak tree.

  • Population: A group of individuals of the same species residing in the same geographic area.

    • Example: A grove of oak trees.

  • Community: A group of interdependent organisms inhabiting the same region and interacting with each other.

    • Example: The oak trees, birds, insects, and fungi in a forest.

  • Ecosystem: A community of living organisms and their physical environment interacting as a system.

    • Example: A forest ecosystem, which includes the oak trees, animals, soil, and climate.

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

    • Example: Earth as a whole, encompassing all forests, oceans, deserts, etc.

Biodiversity and Natural Selection

  • Biodiversity: The variety and variability of life on Earth, encompassing the diversity of species, genetic differences, and ecosystems.

  • Relation to Natural Selection:

    • Higher biodiversity increases the range of traits in a population, allowing for greater adaptability to environmental changes.

    • Natural selection uses variation, favoring organisms best suited to survive and reproduce in their environments.

Biodiversity in Ecosystem Health

  • Healthier Ecosystems:

    • Biodiversity contributes to ecosystem strength against disturbances (disease, climate change).

    • Diverse ecosystems are more efficient and healthy, such as pollination and nutrient cycling.

Population Density

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

  • Factors Affecting Population Density:

    • Availability of resources (food, shelter).

    • Environmental conditions (climate, habitat suitability).

    • Density-Dependent Limiting Factors are factors that affect population growth based on the population size

      - Examples of DDLF: Competition, Predetation, Disease, Overcrowding

    • Density-Independent Limiting Factors are factors that affect population growth regardless of the population size or density

      -Examples of DILF: Natural disaster, Human interaction.


Biotic and Abiotic Factors

/

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

    • Examples:

    1. Plants (producers)

    2. Herbivores (consumers)

    3. Decomposers (fungi, bacteria)

  • Abiotic Factors: Non-living physical and chemical elements (e.g., temperature, water).

    • Examples:

    1. Sunlight

    2. Water

    3. Soil composition

Population Growth Curves

  • Types:

    • Logistic Growth Curve: S-shaped curve, Growth slows, population reaches capacity.

    • Signs of logistic growth: Growth rate decreases. resources become limited. population stabilizes at almost capacity.

    • Exponential Growth Curve: Fast increase. Unlimited (ideal) conditions. (J-shaped curve).

    • Indicators: never seems to stop growing, upwards shape.

Food Chains vs. Food Webs

  • Food Chain: A linear sequence showing energy transfer between organisms.

  • Food Web: A complex network of interconnected food chains illustrating the various feeding relationships in an ecosystem.

Trophic Levels

  • Producers: Organisms that produce energy through photosynthesis; also called autotrophs.

  • Consumers: Organisms that consume other organisms for energy; also referred to as heterotrophs.

  • Types:

    • Herbivores: Consume only plants.

    • Carnivores: Consume only animals.

    • Omnivores: Consume both plants and animals.

    • Decomposers: Break down dead matter for energy (e.g., fungi).

  • Energy Transfer: As energy moves up the food chain, it decreases; typically, only about 10% of energy is transferred to the next trophic level.

Nutrient Cycles and Carbon Cycle

  • Major Nutrient Cycles:

    1. Carbon Cycle

    2. Nitrogen Cycle

    3. Phosphorus Cycle

    4. Water Cycle

  • Importance of Nitrogen Recycling: Essential for amino acids and nucleic acids; supports plant growth.

    • Organisms Benefiting: Decomposers, nitrogen-fixing bacteria.

  • Nitrogen Fixation: the changing of atmospheric ( in the air) nitrogen (N₂) into a tangible/usable form (NH₃) by certain bacteria found in plants sometimes.


Carbon Cycle

  • Processes for Removing Carbon: Photosynthesis by plants; absorption by oceans.

  • Processes for Adding Carbon: Respiration, combustion of fossil fuels, and decomposition.

  • Plants in the Oxygen Cycle: Produce oxygen through photosynthesis, crucial for aerobic organisms.

  • Human Impact on Carbon Cycle: Increased greenhouse gas emissions disrupt balance, leading to climate change.

Ecological Succession

  • Definition: The gradual process by which ecosystems change and develop over time.

  • Types of Succession:

    • Primary Succession: begins in barren areas to transform them.

    • Secondary Succession: Follows a disturbance in an existing ecosystem (e.g., forest fire).

  • Pioneer Species: First species to colonize and prepare the ecosystem for future animals. they appear in previously disrupted or damaged ecosystems (e.g., lichens, mosses).

  • Climax Community: a mature community that has little change in the future.

  • Keystone Species: Species that are extremely important to their environment. The environment would suffer w/o them. (e.g., sea otters, wolves).

Human Impacts on Ecosystems

  • Climate Change: Altered weather patterns affecting biodiversity and habitat.

  • Biomagnification: Accumulation of toxins in organisms at higher trophic levels.

  • Invasive Species: Non-native species that disrupt local ecosystems.

  • Habitat Fragmentation: Division of habitats into smaller, isolated patches lead to biodiversity loss.

  • Deforestation: Clearing forests for agriculture or development reduces carbon sinks and biodiversity.

  • Pollution: Contamination of air or water adversely affects ecosystems and health of organisms.



Take a practice test, if you get any wrong review again!