Principles of Ecology

Chapter 2

Principles of Ecology• Ecology – study of

relationships between living and nonliving parts of the world

• Ernst Haeckel (1866) – first to use the word to name the study of how organisms fit into their environment

• Ecologists: Scientists who study Ecology

Parts of the Environment• Abiotic Factors –

non-living parts of an organism’s environment - Air currents, temperature, moisture, light, soil

• Biotic Factors – all the living things that inhabit the environment

- salmon, bears, trees, algae, microscopic organisms

Levels of Organization

Organism

Population

Community

Ecosystem

Biosphere

Biome

Niche vs. Habitat

• Habitat – place an organism lives out its life

• Niche – role and position a species has in its environment– Includes all biotic and abiotic interactions as

an organism meets its needs for survival– If two species are competing for the same

niche, one will most likely drive the other out and take control of the niche.

• What is your niche?

Niche vs. Habitat vs. Ecosystem

A great blue heron that lives around the Wye Marsh is part of the Wye river ecosystem. The heron and its mate eat fish, frogs, salamanders, snakes, crayfish, mice, aquatic insects, crickets, grasshoppers, and a variety of other insects in Georgian Bay and the Wye Marsh and build a nest in a tree along side the marsh.

• What is the heron’s habitat?• What is the heron’s niche?• What is the heron’s

ecosystem?

Community Interactions• Interactions in a community include

competition for basic needs such as food, shelter, and mates, as well as relationships in which organisms depend on each other for survival

• Competition – Occurs when one or more organism uses a resource at the same time– Water during a drought

• Predation – One organism consuming another organism for food• Predator – the organism that pursues• Prey – the organism that is pursued

Relationships

• All living things form relationships with other living things

• Symbiotic Relationship – a relationship between organisms of two different species that live together in direct contact

Commensalism

• One organism benefits – The other is not affected– Spanish moss on a tree– Barnacles on a whale– Burdock seeds on a passing animal

Mutualism• Both organisms benefit

– Acacia tree and ants (Pseudomyrmex sp.) – tree provides food for the ants and the ants protect the tree from animals that would eat the leaves

– Lichens: algae and fungus living together. Algae provides food (photosynthesis) and the fungus provides protection and attaches the lichen to the rock or wood where it lives.

Parasitism• One organism benefits,

the other is harmed– Some live within the host

• Tapeworms• Heartworms• Bacteria

– Some feed on the external surface of the host• Ticks• Fleas• Mistletoe

– Most do not kill their host (at least not quickly)

Ecosystem Requirements

• #1 - Continuous supply of Energy• #2 – A flow of energy from one

population to another

Obtaining Energy

• Autotrophs - use energy from the sun or energy stored in chemical compounds to produce energy

• Heterotrophs – must consume their energy– Herbivores– Carnivores– Omnivores– Detritivore (AKA

decomposers)

Herbivores

• Eat plants (autotrophs)

Carnivores

• Eat other heterotrophs– Predators – kill their own food– Scavengers – eat animals that are

already dead

Omnivores

• Eat both autotrophs and heterotrophs (plants and animals)

Decomposers and Scavengers

Decomposers – decompose organic matter and

return nutrients to soil, water, and air.

Energy Pyramid• The energy

pyramid is made of several trophic levels

• Trophic Level- feeding level in a food chain or food web

• Autotrophs make up the first level, and heterotrophs make up the remaining levels

• Organisms at each level get their energy from the level before it

Food Chains

• A simple model that shows how energy flows through an ecosystem

• Energy flows in one direction

Food Chain

Food Webs

• Food Web – a model that represents the many interconnected food chains

Ecological Pyramids

• The number of organisms and amount of energy at each trophic levels decreases as you step up the pyramid.

• Biomass (living organic matter) is reduced at each trophic level as well

Cycles of Matter• The bodies of all organisms are built from water

and nutrients such as carbon, nitrogen, and phosphorus

• Matter changes form, but is neither created nor destroyed; it is recycled continuously within and between ecosystems

• Essential nutrients are cycled through biogeochemical processes

• Biogeochemical Cycle: The exchange of matter through the biosphere. These cycles connect living organisms (bio), geological processes (geo), and chemical processes (chemical)

• Organisms are an important part of this cycling system.

Water Cycle• Water is a necessary substance for the life

processes of all living organisms.• Water is found in the atmosphere, on the

surface of Earth and underground, and in living organisms.

• The water cycle, also called the hydrologic cycle, is driven by the Sun’s heat energy, which causes water to: – evaporate from water reservoirs (the

ocean, lakes, ponds, rivers)– condense into clouds – then precipitate back to water bodies

on Earth in the form of rain, sleet, or hail

Carbon Cycle• All living things are composed of molecules that

contain carbon• Carbon and oxygen make up molecules essential

for life, including carbon dioxide and simple sugar

• Organisms play a major role in recycling carbon from one form to another

• During photosynthesis, plants release carbohydrates and oxygen back into the air

• These carbohydrates are used as a source of energy for all organisms in the food web

Nitrogen Cycle• Nitrogen is an

element found in proteins

• Nitrogen is found in the atmosphere, but organisms cannot use nitrogen directly from the atmosphere

• Nitrogen is captured from the air by species of bacteria that live in water, the soil, or grow on the roots of some plants

• This process is called nitrogen fixation

Nitrogen Recycling Processes

1. Nitrogen is introduced into the soil through precipitation

2. They can also come from fertilizers3. Plants absorb nitrogen compounds from the soil

and convert them into proteins4. Animals eat the plants and use the nitrogen to

build protein5. - 6. When organisms poop, pee, or die, decomposers break them down and the nitrogen is returned to the soil in the form of ammonia7. Organisms in the soil convert ammonia into nitrogen compounds and soil bacteria convert nitrogen compounds back into nitrogen gas in a process called denitrification

The Phosphorous Cycle

• Phosphorus is essential for the growth and development of organisms

• In the short-term cycle, phosphorus is cycled from the soil to producers, and from producers to consumers

• In the long-term cycle, erosion of rocks that contain phosphorus slowly adds phosphorus to the cycle