ECOLOGY•The study of interactions

among organisms & their environment

• Ecologists divide environmental factors that influence organisms into 2 groups: ABIOTIC and BIOTIC.

ABIOTIC• NONLIVING PARTS OF THE

ENVIRONMENT• Ex: Water, light, temperature,

air, soil• Air is a mixture of 3 main gases:

oxygen, carbon dioxide, & nitrogen (used by plants & animals)

BIOTIC•Living or once-living organisms in the environment

•Can be arranged into levels of organization:

1. organism

•1 individual from a population

•Example: catfish

2. Population

•All the individuals of one species that live in the same area at the same time.

•Example: All the catfish living in a lake at the same time

3. community

•Populations of different species that interact in some way

•Example: Population of bass and all the species they interact with it

4. ecosystem•All the communities in an area & the abiotic factors that affect them

•Example: lake, pond, coral reef, forest, etc.

5. Biome•Large region with plants & animals well adapted to soil & climate of the region

•Example: Mountain, rainforests, tundra, desert, grasslands, temperate forests (where we live)

6. biosphere•All the ecosystems on earth; the part of the earth that supports life

•Example: Top part of the earth’s crust, all the waters that cover the Earth’s surface, the surrounding atmosphere, & all the biomes.

Energy flow through an ecosystem

• Energy transfer: all energy comes from the sun and is transferred from one organism to another.

• Most of the interactions among members of different species occur when one organism feeds on another

•When one organism is food for another organism, some of the energy in the first organism (the food) is transferred to the second organism (the eater).

Producers• Organisms that

take in & use energy from the sun or some other source to produce food.

• Examples: algae & plants

Consumers• Organisms that

take in energy when they feed on producers or other consumers.

• 1st level consumer: eats the producers

• 2nd level consumer: eats the 1st level consumer

• Ex.: frog, lion

Decomposers• Organisms that take

in energy (food) from dead organisms breaking down the remains of organisms & returning it to the soil so other plants

can grow.• Ex.: bacteria,

mushrooms (fungi)

• Niche: a species’ specific role in its community (habitat)

• Ex. A red fox is a predator that feeds on small mammals, amphibians & insects in its habitat

•Movement of energy through a community can be diagrammed as a food chain or food web.

Food chain•Simple way of showing how energy passes from one organism to another.

•Usually 3 or 4 links

Example of food chain:

1.Water plant insects

bluegill bass

2.Grass grasshopper frog snake owl

Food web• Series of

overlapping food chains that exist in an ecosystem

• More complete model of feeding relationships.

Energy pyramid• Compares

energy available at each level of the food chain in an ecosystem

• As you move from level to level, energy decreases.

• Energy enters most ecosystems in the form of heat from the sun.

• Then it’s transferred into chemical energy by producers then passed to consumers as food.

• Then given back off as heat.

Cycles of matter

•Many important materials (water, carbon, & nitrogen) make up your body & cycle through the environment.

1. Water cycle• Process of

evaporation, condensation, & precipitation

2. Carbon cycle• Plants absorb CO2 &

combines it with water for their needs

• In photosynthesis, the plants use the carbon atoms from the CO2 to make sugars.

Carbon cycle continued…

• Animals eat the producers & other consumers and return the CO2 back into the air through respiration.

• Animals & plants die then carbon is returned back to soil during decomposition.

Nitrogen Cycle….

• Nitrogen is “fixed” by bacteria in the soil then absorbed by plants & animals for their use.

Major Biomes of the world:

• 1. Aquatic: includes freshwater and saltwater (oceans)

• 2. Desert: – 2 Kinds: hot/dry(little rain) and cold (snow),

few plants grow in either and few animals live in them Ex. Great Basin in Utah, Sahara Desert in Northern Africa

• 3. Forest (rainforest, deciduous): lots of different vegetation & animals that live there, climate can be moderate temperatures or really cold

rainforest Deciduous forest

• 4. Grasslands: mainly grasses, flowers and herbs grow here (not a lot of trees), animals, climate varies (can be humid/wet and hot summer/cold winter) Ex. Plains of Africa

• 5. Tundra- coldest biome, few plants and few animals, located in the Northern Hemisphere

Interactions among living

organisms

1. Population size

•The number of individuals in a population

2. Population Density

•The number of individuals in a population that occupy a definite area

Classroom population density

•Length of room (m) X width (m)

# of students=A (in m2)= how much space each person has

3. Population spacing

•How organisms are arranged in a given area

•Can be evenly, random, or clumped

EVEN

random

clumped

4. Limiting factors

•Any biotic or abiotic factor that limits the number of individuals in a population

•Ex: drought, fewer plants, fewer nesting sites, predators

•Food, water, & space are all factors in the growth populations in an ecosystem

•If an environment had no limiting factors, the population would INCREASE.

5. Carrying capacity

•Largest number of individuals of a species that an environment can support & maintain for a long period of time.