Ecology

Ecology is the study of interactions among organisms and between organisms and their environment.

Ecology: Levels of Organization

Individual

Population

Community

Ecosystem

Biome

Biosphere

Ecological Methods

• Observing: simple or complex; first step in asking ecological questions

• Experimenting: test hypotheses in a lab or in the field

• Modeling: gain insight into complex phenomena (global warming)

Ecological Niche

Niche defines an animal’slifestyle…• habitat• nutrition• foraging• territory

Niche includes everythingan animal does or uses inorder to survive.

Ecology: Energy Flow

• Every organism needs energy.

• Sunlight is the main energy source for life.

• Less than 1% of sunlight is used by organisms.

• Where does the rest of the sunlight go?

Photograph courtesy philip.greenspun.com

Ecology: Energy Flow

• photosynthesis: use of light energy to producecarbohydrates

• autotrophs make their own food.

• autotrophs are producers

• Why?

Ecology: Energy Flow

• sunlight is not available to all organisms

• chemosynthesis: use of chemical energy to produce carbohydrates

• most chemotrophs are bacteria and algae

• are they autotrophs?

Deep sea hydrothermal vent worms

Ecology: Energy Flow

• autotroph: produces its own food• heterotroph: acquires energy from other

organisms• What is a producer?• What is a consumer?• Are heterotrophs producers or consumers?• consumers:

primarysecondary tertiary quaternary

Ecology: Energy Flow

• heterotrophs are consumers• herbivores eat plants• carnivores eat meat• omnivores eat plants and meat• insectivores eat _____________• detritivores feed on remains• decomposers break down organic matter• Where are decomposers in a food chain?

Ecology: Feeding Relationships

• Energy flows through an ecosystem in one direction (arrows) from the sun or inorganic compounds to producers to consumers.

• Food chain: diagram that shows simple feeding relationships.

• Trophic level: each step in a food chain

• All food chains start with a producer.

Feeding Relationships: Food Chain squid (tertiary consumer)

small fish (secondary consumer)

zooplankton (primary consumer)

algae (producer)

Students be careful!

Remember: the arrowshows the directionenergy flows in an ecosystem.

In this example, theLeopard seal eats the penguin and as a result,gets the energy.

Ecology: Feeding Relationships

• A food web is a network of complex feeding relationships that connects multiple food chains.

• If one species is lost from a food web, all other species are affected.

Terrestrial Food Web

Aquatic Food Web

My Favorite Food Web

Matt Pendley, Buford High School, Buford, GA

Ecology: Community Interactions

Competition: when organisms try to use a resource in short supply at the same time

and same place.

Ecology: Community Interaction

Predation: when one organism captures and eats another organism.

Ecology: Community Interaction

Symbiosis: any relationship in which two species live closely together.

Ecology: Symbiosis

Mutualism: when both species benefit from theinteraction.

In this example, the seaanemone is cleaned bythe clown fish, who inturn is protected by theanemone’s stinging tentacles.

Ecology: Symbiosis

Commensalism: whenone species benefitsfrom the interactionand the host species is unaffected.

The leafy plant is anepiphyte, growing onanother plant only forsupport.

Ecology: Symbiosis

Parasitism: interactionin which one organismbenefits and the other organism (host) isharmed.

Does the host die as aresult?Asian tiger mosquito

Ecological Pyramids: Energy Pyramid

(energy flow in a community)• each trophic level

represents a different group of organisms in a food chain

• about 10% of the energy available at each trophic level is transferred to organisms at the next trophic level

• energy is lost as heat and in life processes

Ecological Pyramids: Biomass Pyramid

• biomass is the total amount of living tissue• expressed as grams of organic matter per unit area• biomass pyramid represents the potential amount of

food available at each trophic level• normally the greatest biomass is at the base

Ecological Pyramids: Numbers Pyramid

• based on the numbers of individuals at each trophic level

• some number pyramids look like biomass & energy pyramids, some do not

• in this example, the oak tree has a large amount of energy and biomass, but it is only one organism

Laws of Ecology

All things are interconnected.

Everything goes somewhere.

There’s no such thing as a free lunch.

Nature bats last.Ecology: A Pocket Guide by Ernest Callenbach