BIOLOGY J

Ecology, Symbiotic Relationships, and Biomes

Ecology

The scientific study of interactions between organisms and their environment

Levels of Ecological Organization

Organism, Population, Community, Ecosystem, Biome, Biosphere

Ecosystem

A community of organisms interacting with their physical environment

Biotic Factors

Living components of an ecosystem (e.g., plants, animals, bacteria)

Abiotic Factors

Nonliving components of an ecosystem (e.g., temperature, water, sunlight, soil)

Habitat

The natural environment in which an organism lives

Niche

The role or function of an organism in its ecosystem

Symbiosis

A close ecological relationship between two different species

Mutualism

A symbiotic relationship where both species benefit (e.g., bees and flowers)

Commensalism

A symbiotic relationship where one species benefits and the other is unaffected (e.g., barnacles on whales)

Parasitism

A symbiotic relationship where one species benefits and the other is harmed (e.g., ticks on a dog)

Competition

Occurs when two species compete for the same resources in an ecosystem

Predation

Interaction where one organism (predator) hunts and eats another (prey)

Food Chain

A linear sequence showing the flow of energy through organisms via consumption

Food Web

A complex network of interconnected food chains in an ecosystem

Trophic Levels

Levels in a food chain: producers, primary consumers, secondary consumers, tertiary consumers

Energy Pyramid

A diagram showing energy loss (usually 10% passed on) through trophic levels

Biomes

Large geographic regions with similar climates and ecosystems

Tundra

Cold, dry biome with permafrost; few trees; found in Arctic regions

Taiga (Boreal Forest)

Cold forest biome with coniferous trees; long winters, short summers

Temperate Deciduous Forest

Moderate climate, four seasons, broadleaf trees that shed annually

Tropical Rainforest

Hot, humid biome with high biodiversity and rainfall; found near the equator

Desert

Dry biome with very low rainfall; extreme temperatures; plants like cacti

Grassland (Savanna/Prairie)

Open biome with grasses, few trees; used for agriculture and grazing

Freshwater Biome

Includes rivers, lakes, and wetlands; supports diverse aquatic life

Marine Biome

Largest biome; includes oceans, coral reefs, and estuaries; high salt content

Estuary

A coastal area where freshwater and saltwater mix; highly productive ecosystem

Biodiversity

The variety of life in an area; important for ecosystem stability and resilience

Sustainability

The ability to maintain ecological balance and conserve resources for future generations

Components of an Ecosystem

Biotic (living things) and abiotic (nonliving things like air, water, soil, temperature)

Producers

Organisms (usually plants) that use photosynthesis to make their own food

Consumers

Organisms that eat other organisms; include herbivores, carnivores, omnivores

Decomposers

Organisms like fungi and bacteria that break down dead matter and recycle nutrients

Energy Flow

Energy flows from the sun to producers and then to various levels of consumers

Nutrient Cycling

The process of recycling nutrients like carbon, nitrogen, and water within an ecosystem

Ecological Succession

Natural process of change in ecosystems over time, leading to a stable climax community

Primary Succession

Starts on bare rock or no soil (e.g., after volcanic eruption); pioneer species like lichens

Secondary Succession

Occurs in areas where soil exists but life has been disturbed (e.g., after fire or flood)

Climax Community

A stable, mature community that undergoes little or no change in species composition

Carrying Capacity

The maximum population size an ecosystem can sustain over time

Limiting Factors

Environmental factors that restrict population growth (e.g., food, space, water)

Interdependence

All organisms in an ecosystem rely on each other to survive and maintain balance

Population

A group of individuals of the same species living in a specific area

Population Density

The number of individuals per unit area or volume

Population Size

The total number of individuals in a population

Population Distribution

The way individuals are spread out in an area; can be clumped, uniform, or random

Birth Rate

The number of births per 1,000 individuals per year in a population

Death Rate

The number of deaths per 1,000 individuals per year in a population

Immigration

The movement of individuals into a population from another location

Emigration

The movement of individuals out of a population to another location

Population Growth

The increase in the number of individuals in a population

Exponential Growth

Rapid population increase under ideal conditions; forms a J-shaped curve

Logistic Growth

Population growth that slows as it reaches carrying capacity; forms an S-shaped curve

Density-Dependent Factors

Factors that affect population size more strongly as population density increases (e.g., disease, competition, predation)

Density-Independent Factors

Factors that affect population size regardless of population density (e.g., weather, natural disasters)

Overpopulation

When a population exceeds the carrying capacity of its environment, leading to resource depletion

Predator-Prey Relationship

A biological interaction where the predator feeds on the prey; helps regulate population sizes

Population Dynamics

The study of changes in population size and composition over time

Age Structure

The distribution of individuals among different ages in a population

Survivorship Curve

A graph showing the number of survivors in a population over time; three types (Type I, II, III)

Reproductive Strategy

The method by which a species reproduces; can be r-strategy (many offspring, low care) or K-strategy (few offspring, high care)

Community

All the populations of different species living and interacting in a particular area

Species Diversity

The number and variety of species in a community; includes species richness and evenness

Species Richness

The number of different species in a community

Species Evenness

How evenly individuals are distributed among the different species in a community

Ecological Niche

The specific role or function of a species within a community

Community Interactions

Relationships between species in a community; includes predation, competition, symbiosis

Interspecific Competition

Competition between individuals of different species

Intraspecific Competition

Competition between individuals of the same species

Keystone Species

A species that has a major impact on the structure and function of a community

Trophic Structure

The feeding relationships among organisms in a community

Succession

The natural process by which ecosystems and communities change over time

Invasive Species

Non-native species that spread rapidly and disrupt community balance

Community Stability

The ability of a community to resist or recover from disturbances

Abiotic Limiting Factor

A non-living factor that can limit the growth of a population (e.g., drought limiting plant growth)

Biotic Limiting Factor

A living factor that restricts population size (e.g., predators limiting prey populations)

Biome

A large region characterized by specific climate conditions, plant life, and animal communities

Savanna

A grassy biome with scattered trees, warm temperatures, and seasonal rainfall; common in Africa

Grassland

A biome dominated by grasses, few trees, and moderate rainfall; includes prairies and steppes

Chaparral

A coastal biome with hot, dry summers and mild, wet winters; has shrubs and fire-adapted plants

Climate

The average weather conditions in an area over a long period; determines biome type

Adaptations

Traits that help organisms survive in a specific biome (e.g., thick fur in tundra animals, waxy leaves in desert plants)

Human Impact

Activities like deforestation, pollution, and climate change that can alter or destroy biomes

Pioneer Species

The first organisms to colonize a barren environment (e.g., lichens, mosses)

Biodiversity in Succession

Increases over time as more species colonize and establish

Soil Formation in Primary Succession

Formed by weathering of rock and accumulation of organic material from pioneer species

Disturbances

Natural or human events (e.g., fire, logging, storms) that disrupt ecosystems and may start succession

Human Impact on Succession

Can accelerate, delay, or prevent succession (e.g., pollution, land development)

Example of Primary Succession

A lava flow cooling and being colonized by mosses and lichens

Example of Secondary Succession

Forest regrowing after a wildfire

Role of Decomposers

Break down dead organisms and recycle nutrients, aiding in soil development and plant growth

Difference Between Primary and Secondary

Primary starts without soil; secondary starts with soil already present

Sun

The primary source of energy for nearly all ecosystems

Producers (Autotrophs)

Organisms like plants and algae that capture energy from sunlight through photosynthesis

Consumers (Heterotrophs)

Organisms that obtain energy by eating other organisms

Primary Consumers

Herbivores that eat producers (e.g., rabbits, cows)

Secondary Consumers

Carnivores or omnivores that eat primary consumers (e.g., snakes, birds)

Tertiary Consumers

Carnivores that eat secondary consumers (e.g., hawks, lions)

Trophic Level

Each step in a food chain or food web (producer, consumer, etc.)

Heat Loss in Ecosystems

Most energy is lost as heat during metabolic processes like respiration