Principles of Ecology

O’Connor/Chapter 2

Ecology

• The study of interactions that take place between organisms and their environments.

• Biosphere ~ the portion of Earth that supports living things. Extends from high in the atmosphere to the bottom of the oceans.

Living vs. Nonliving

Abiotic Factors

• Nonliving parts parts of an organism’s environment.

• Ex. Air currents, temp., moisture, light, and soil.

• Biotic Factors

• All living organisms that inhabit an environment.

• Ex. Animals & plants.

Levels of Organisms

• To understand interactions of the biotic and abiotic parts of the world, ecologists have organized the living world into levels –

The organism itself, populations, communities & ecosystems.

Populations

• A group of organisms, all of the same species, which interbreed and live in the same area at the same time.

Map of populations by country

Biological Communities

• Interacting populations in a certain area at a certain time.

Ecosystems

• Interacting populations in a biological community and the community’s abiotic factors.

Types of Ecosystems

Terrestrial• Forrest• Old farm field• Meadow• Yard• Garden plot empty lot• Compost heap• Volcano site• Rotting log

Aquatic• Freshwater

– Pond– Lake– Stream– Estuary

Marine (salt H2O)-ocean-estuary-aquarium

Other Ecosystems

• Human Body - ex. Skin

• Buildings - ex. Basement

• Food - moldy food

Habitat

• A place where an organism lives out its life.

Niche

• A role or position a species has in its environment- how it meets its specific needs for food & shelter, how & where it survives, and where it reproduces in its environment.

Symbiosis

• Relationship where there is a close and permanent association between organisms of different species. Three kinds:

• Mutualism

• Commensalism

• parasitism

Mutualism

• Both species benefit + +

• Ex. Ants & acacia trees- ants feed off it & protect it from damaging predators

Commensalism + o

• One species benefits and the other species is neither harmed nor benefited.

Parasitism + -

• When one species benefits at the expense of another species.

Flea bites on human

How organisms Obtain Energy

• The producers – autotrophs

• The consumers – heterotrophs

• The decomposers

Energy Flow Through the Ecosystem

                                                                                                                                               

                     

A food Chain - Web

• A model that scientists use to show how matter & energy move through an ecosystem.

• In a chain nutrients & energy move from autotrophs to heterotrophs & eventually to decomposers.

The arrow points to the mouth the eats it.

Which of these is an omnivore?

Levels of heterotrophs

• First –order (primary consumers)ex. Herbivores like deer, turtles & fish. Obtain food by eating photosynthetic organisms.

• Second-order (secondary consumers) Carnivores like owls. They eat first order heterotrphs like mice.

• Third-order -Carnivores that feed on second order heterotrophs. Ex. Bears, lions, humans

Biomass

• Foundation species (also known as primary producers) harvest an energy source such as sunlight and turn it into biomass.

• Primary production is generation of biomass through photosynthesis.

Biomass Production

The highest producers of biomass are

• tropical rain forests, 2000 g/m²/yr of biomass

• swamps and marshes, 2500 g/m²/yr of biomass

• algal beds and reefs, 2000 g/m²/yr of biomass

• Lowest producers are

• deserts and frozen areas (less than 200 g/m²/yr of biomass)

Trophic Levels

Cycles in nature

• The water cycle• The carbon cycle• The nitrogen cycle• The phosphorus cycle

• The materials of life, such as carbon & nitrogen, are used and reused as they cycle through the ecosystem.

Water Cycle

Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle