The Principles of Ecology

Ecology The study of how living things interact

with each other and with their environment By necessity it overlaps with geology,

geography, climatology and other sciences.

An organism is an individual living thing Like every other organism all organisms

have two basic needs ENERGY AND MATTER

Ecology Matter and energy are obtained from

the environment Organisms depend on and are influenced

by their environment Contains two kinds of factors

Biotic – living things Other organisms as well as members of the same

species Abiotic – nonliving aspects

Sunlight, Soil, Temperature, Water

The Ecosystem A unit of nature and the focus of the

study of ecology All the biotic and abiotic factors in an

area and how they interact with each other They vary in size

Lake Dead log

Ecosystems and Energy These are not closed systems

They need inputs of energy Most comes from sunlight A small amount comes from chemical

compounds Matter is not constantly added to an

ecosystem Matter is recycled

Water, Carbon, Nitrogen, Phosphorus

Niche Refers to the role of a species in its

ecosystem Includes the way the species interacts

with the biotic and abiotic factors of the environment.

The niche of a species The food it eats and how the food is

obtained

Bird Niches

Habitat This is the physical environment in

which a species lives and to whit it is adapted Mainly determined by abiotic factors

Temperature and rainfall These factors also influence the traits of the

organisms that live there

Competitive Exclusion Principle A given habitat may have many different

species, but each species must have a different niche.

Two different species cannot occupy the same niche in the same place for very long. This is know as the competitive exclusion

principle They compete for the same food and other

resource found in the environment

Competitive Exclusion Principle

Flow of Energy Energy enters in the form of sunlight or

chemical energy Some organisms use the energy to make

food Other organisms get energy by eating

food

Producers Produce food for themselves and other

organisms They are called autotrophs

Photoautotrophs Plants, Algae, and Bacteria

Chemoautotrophs Some bacteria, archea

Chemoautotrophs

Consumers Depend on other organisms for food

All animals and fungi Many Bacteria Some plants Called Heterotrophs

Herbivores Consume producers

Deer, Rabbits, Mice Carnivores (Obligate carnivores-can’t eat

plants Consume animals

Omnivores Eat both plants and animals

Decomposers Break down the remains and other waste

and release simple inorganic molecules back into the environment Scavengers – consume the soft tissues of

dead animals Vultures, Raccoons, and Blowflies

Detritivores – consume detritus Dead leaves, animal feces, and other organic

debris Earthworms, Millipedes, dung beetles on land Bottom feeders in water like sea cucumbers and

catfish Saprotrophs – feed on what’s left

Fungi, single-celled protozoa

The Ultimate Recyclers http://science.kqed.org/quest/video/scie

nce-on-the-spot-banana-slugs-unpeeled/

Food Chains and Food Webs They Show Who eats Whom Food Chains

Represent a single pathway through which energy and matter flow through an ecosystem

Food chains are generally simpler than what really happens in nature Typically not a one-on-one relationship

Food ChainWhere would you add the decomposers to this picture?

http://www.youtube.com/watch?v=TE6wqG4nb3M

Food Webs Represents multiple pathways through

which energy and matter flow through the ecosystem Includes many intersection food chains Shows that most organisms eat, and are

eaten, by more than one species.

Food Web

Trophic Levels The feeding positions in a food web are

called trophic levels Most food webs have 2-3 trophic levels

with a typical maximum of 4 levels

Trophic LevelsTrophic Level Where it Gets

FoodExample

1st – These are the producers

Make their own food

Plants

2nd Trophic Level – Primary Consumers

Consume Producers

Mice eat plants

3rd Trophic Level – Secondary Consumers

Consume Primary Consumers

Snakes eating mice

4th Trophic Level – Tertiary Consumers

Consumer Secondary Consumers

Hawks eat Mice

Trophic Levels and Energy Only about 10% of the energy from one

level is available for the next level So: What happens to the other 90%

Used for metabolic processes Given off to the environment as heat This is called the 10% rule

Energy Pyramid

Trophic Levels and Biomass

With less energy available to higher trophic levels there tend to be fewer organisms on those levels

Organisms at the higher trophic levels also tend to be larger in size

Biomass is the total mass or organisms at a trophic level

Ecological Pyramid

Summary Ecology is the study of how living things interact

with each other and their environment. The environment include abiotic and biotic factors

An ecosystem consists of all the biotic and abiotic factors. A niche refers to the role of a species in its ecosystem. A habitat is the physical environment in which a species lives and to which it is adapted. Two different species can’t occupy the same niche in the same place for very long.

Summary, Continued Ecosystems require constant inputs of

energy from sunlight and chemicals. Producers use energy and inorganic molecules to make food. Consumers take in food by eating producers or other living things. Decomposers break down dead organisms and other organic wastes and release inorganic molecules back to the environment

Summary Continued One More Time

Food chains and food webs are diagrams that represent feeding relationships. They model how energy and matter move through an ecosystem.

The different feeding positions in a food chain or web are called trophic levels. Generally, there are no more than four trophic levels because energy and biomass decrease from lower to higher levels.