KEY CONCEPT INTERDENPENDENCE – all organisms interact with: other organisms in their surroundings the nonliving portion of their environment Their survival depends on these interactions

ECOLOGY – the scientific study of interactions among organisms and between organisms and their environment, or surroundings.

To understand relationships within the biosphere, ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere. The levels of organization that ecologists study include: Species/Organisms Populations Communities Ecosystems Biomes

Organism ORGANISM – an independent individual that possesses all the characteristics of life.

SPECIES – a group of organisms so similar to one another that they can breed and produce fertile offspring.

Organism Population POPULATION – a group of the same species that lives in one area.

Organism Population Community COMMUNITY – is a group of different species that live together in one area.

Organism Population Community Ecosystem ECOSYSTEM – all of the organisms as well as the climate, soil, water, rocks and other nonliving things in a given area.

Organism Population Community Ecosystem Biome BIOME (BIOSHPERE) – is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.

KEY CONCEPT Every ecosystem includes both living and nonliving factors.

An ecosystem includes both biotic and abiotic factors. BIOTIC FACTORS – are living things. –plants –animals –fungi –bacteria plants

ABIOTIC FACTORS – are nonliving things. –moisture –temperature –wind –sunlight –soil moisture sunlight

THE NICHE: NICHE – the specific role, or way of life, of a species within its environment. –Includes: the range of conditions a species can tolerate the resources it uses the methods it uses to obtain those resources the number of offspring it has its time for reproduction all other interactions with its environment

KEYSTONE SPECIES –a species that, when it fills its niche, has an unusually large effect on its ecosystem.

Keystone species form and maintain a complex web of life. creation of wetland ecosystem increased waterfowl Population increased fish population nesting sites for birds keystone species

KEY CONCEPT Energy Transfer: life in an ecosystem requires a source of energy.

PRODUCERS – provide energy for other organisms in an ecosystem. Producers get their energy from non-living resources. Producers are also called autotrophs because they make their own food.

Almost all producers obtain energy from sunlight. Photosynthesis in most producers uses sunlight as an energy source. Chemosynthesis in prokaryote producers uses chemicals as an energy source.

CONSUMERS – organisms that get their energy by eating other living or once-living resources. Consumers are also called heterotrophs because they feed off of different materials.

Consumers are not all alike. –HERBIVORES – eat only plants. –CARNIVORES – eat only animals. –OMNIVORES – eat both plants and animals. –DETRITIVORES – eat dead organic matter. –DECOMPOSERS – are detritivores that break down organic matter into simpler compounds. carnivore decomposer

SPECIALISTS – consumers that primarily eat one specific organism or a very small number of organisms. GENERALISTS – consumers that have a varying diet.

KEY CONCEPT Food chains and food webs model the flow of energy in an ecosystem.

A food chain is a model that shows a sequence of feeding relationships. FOOD CHAIN – single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer. –A food chain follows the connection between one producer and a single chain of consumers within an ecosystem. DESERT COTTONTAILGRAMA GRASSHARRIS’S HAWK

A food web shows a complex network of feeding relationships. FOOD WEB – interrelated food chains that emphasize complicated feeding relationships and energy flows in an ecosystem. An organism may have multiple feeding relationships in an ecosystem.

KEY CONCEPT When one organism eats another, molecules are metabolized and energy is transferred.

TROPHIC LEVEL – an organism’s position in a sequence of energy transfers. –Primary consumers – herbivores that eat producers. –Secondary consumers – carnivores that eat herbivores. –Tertiary consumers – carnivores that eat secondary consumers. –Omnivores (such as humans) – eat both plants and animals, may be listed at different trophic levels in different food chains.

energy transferred energy lost An energy pyramid shows the distribution of energy among trophic levels. ENERGY PYRAMID – compaes energy used by producers and other organisms on trophic levels. Between each tier of an energy pyramid, up to 90 percent of the energy is lost into the atmosphere as heat. Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms. BIOMASS – is a measure of the total dry mass of organisms in a given area. tertiary consumers secondary consumers primary consumers producers 75 g/m2 150g/m2 675g/m2 2000g/m2 producers 2000g/m2

A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem. tertiary consumers secondary consumers primary consumers producers ,000 5,000,000 producers A vast number of producers are required to support even a few top level consumers.

ECOSYSTEM RECYCLING: Matter cycles in and out of an ecosystem.

Elements essential for life also cycle through ecosystems. BIOGEOCHEMICAL CYCLE – the movement of a particular chemical through the biological and geological parts of an ecosystem.

THE WATER CYCLE: Water cycles through the environment. WATER/HYDROLOGIC CYCLE – the circular pathway of water on Earth.

fossil fuels photosynthesis carbon dioxide dissolved in water decomposition of organisms respiration carbon dioxide in air photosynthesis combustion respiration THE CARBON CYCLE: –The carbon cycle moves carbon from the atmosphere, through the food web, and returns to the atmosphere. –Carbon is emitted by the burning of fossil fuels. –Some carbon is stored for long periods of time in areas called carbon sinks.

nitrogen in atmosphere animals denitrifying bacteria nitrifying bacteria nitrifying bacteria ammonium ammonification decomposers plant nitrogen-fixing bacteria in soil nitrogen-fixing bacteria in roots nitrates nitrites The nitrogen cycle mostly takes place underground. –Some bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation. –Some nitrogen-fixing bacteria live in nodules on the roots of plants; others live freely in the soil. THE NITROGEN CYCLE:

geologic uplifting rain weathering of phosphate from rocks runoff sedimentation forms new rocks leaching phosphate in solution animals plants decomposers phosphate in soil The phosphorus cycle takes place at and below ground level. –Phosphate is released by the weathering of rocks. –Phosphorus moves through the food web and returns to the soil during decomposition. – Phosphorus leaches into groundwater from the soil and is locked in sediments. THE PHOSPHOROUS CYCLE:

Oxygen cycles indirectly through an ecosystem by the cycling of other nutrients. The main processes involved in the oxygen cycle are photosynthesis and respiration. oxygen respiration carbon dioxide photosynthesis THE OXYGEN CYCLE: